// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2002 Andi Kleen, SuSE Labs.
 * Thanks to Ben LaHaise for precious feedback.
 */
#include <linux/highmem.h>
#include <linux/memblock.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/pfn.h>
#include <linux/percpu.h>
#include <linux/gfp.h>
#include <linux/pci.h>
#include <linux/vmalloc.h>
#include <linux/libnvdimm.h>
#include <linux/vmstat.h>
#include <linux/kernel.h>

#include <asm/e820/api.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/proto.h>
#include <asm/memtype.h>
#include <asm/set_memory.h>

#include "../mm_internal.h"

/*
 * The current flushing context - we pass it instead of 5 arguments:
 */
struct cpa_data {
        unsigned long   *vaddr;
        pgd_t           *pgd;
        pgprot_t        mask_set;
        pgprot_t        mask_clr;
        unsigned long   numpages;
        unsigned long   curpage;
        unsigned long   pfn;
        unsigned int    flags;
        unsigned int    force_split             : 1,
                        force_static_prot       : 1,
                        force_flush_all         : 1;
        struct page     **pages;
};

enum cpa_warn {
        CPA_CONFLICT,
        CPA_PROTECT,
        CPA_DETECT,
};

static const int cpa_warn_level = CPA_PROTECT;

/*
 * Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings)
 * using cpa_lock. So that we don't allow any other cpu, with stale large tlb
 * entries change the page attribute in parallel to some other cpu
 * splitting a large page entry along with changing the attribute.
 */
static DEFINE_SPINLOCK(cpa_lock);

#define CPA_FLUSHTLB 1
#define CPA_ARRAY 2
#define CPA_PAGES_ARRAY 4
#define CPA_NO_CHECK_ALIAS 8 /* Do not search for aliases */

static inline pgprot_t cachemode2pgprot(enum page_cache_mode pcm)
{
        return __pgprot(cachemode2protval(pcm));
}

#ifdef CONFIG_PROC_FS
static unsigned long direct_pages_count[PG_LEVEL_NUM];

void update_page_count(int level, unsigned long pages)
{
        /* Protect against CPA */
        spin_lock(&pgd_lock);
        direct_pages_count[level] += pages;
        spin_unlock(&pgd_lock);
}

static void split_page_count(int level)
{
        if (direct_pages_count[level] == 0)
                return;

        direct_pages_count[level]--;
        if (system_state == SYSTEM_RUNNING) {
                if (level == PG_LEVEL_2M)
                        count_vm_event(DIRECT_MAP_LEVEL2_SPLIT);
                else if (level == PG_LEVEL_1G)
                        count_vm_event(DIRECT_MAP_LEVEL3_SPLIT);
        }
        direct_pages_count[level - 1] += PTRS_PER_PTE;
}

void arch_report_meminfo(struct seq_file *m)
{
        seq_printf(m, "DirectMap4k:    %8lu kB\n",
                        direct_pages_count[PG_LEVEL_4K] << 2);
#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
        seq_printf(m, "DirectMap2M:    %8lu kB\n",
                        direct_pages_count[PG_LEVEL_2M] << 11);
#else
        seq_printf(m, "DirectMap4M:    %8lu kB\n",
                        direct_pages_count[PG_LEVEL_2M] << 12);
#endif
        if (direct_gbpages)
                seq_printf(m, "DirectMap1G:    %8lu kB\n",
                        direct_pages_count[PG_LEVEL_1G] << 20);
}
#else
static inline void split_page_count(int level) { }
#endif

#ifdef CONFIG_X86_CPA_STATISTICS

static unsigned long cpa_1g_checked;
static unsigned long cpa_1g_sameprot;
static unsigned long cpa_1g_preserved;
static unsigned long cpa_2m_checked;
static unsigned long cpa_2m_sameprot;
static unsigned long cpa_2m_preserved;
static unsigned long cpa_4k_install;

static inline void cpa_inc_1g_checked(void)
{
        cpa_1g_checked++;
}

static inline void cpa_inc_2m_checked(void)
{
        cpa_2m_checked++;
}

static inline void cpa_inc_4k_install(void)
{
        data_race(cpa_4k_install++);
}

static inline void cpa_inc_lp_sameprot(int level)
{
        if (level == PG_LEVEL_1G)
                cpa_1g_sameprot++;
        else
                cpa_2m_sameprot++;
}

static inline void cpa_inc_lp_preserved(int level)
{
        if (level == PG_LEVEL_1G)
                cpa_1g_preserved++;
        else
                cpa_2m_preserved++;
}

static int cpastats_show(struct seq_file *m, void *p)
{
        seq_printf(m, "1G pages checked:     %16lu\n", cpa_1g_checked);
        seq_printf(m, "1G pages sameprot:    %16lu\n", cpa_1g_sameprot);
        seq_printf(m, "1G pages preserved:   %16lu\n", cpa_1g_preserved);
        seq_printf(m, "2M pages checked:     %16lu\n", cpa_2m_checked);
        seq_printf(m, "2M pages sameprot:    %16lu\n", cpa_2m_sameprot);
        seq_printf(m, "2M pages preserved:   %16lu\n", cpa_2m_preserved);
        seq_printf(m, "4K pages set-checked: %16lu\n", cpa_4k_install);
        return 0;
}

static int cpastats_open(struct inode *inode, struct file *file)
{
        return single_open(file, cpastats_show, NULL);
}

static const struct file_operations cpastats_fops = {
        .open           = cpastats_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int __init cpa_stats_init(void)
{
        debugfs_create_file("cpa_stats", S_IRUSR, arch_debugfs_dir, NULL,
                            &cpastats_fops);
        return 0;
}
late_initcall(cpa_stats_init);
#else
static inline void cpa_inc_1g_checked(void) { }
static inline void cpa_inc_2m_checked(void) { }
static inline void cpa_inc_4k_install(void) { }
static inline void cpa_inc_lp_sameprot(int level) { }
static inline void cpa_inc_lp_preserved(int level) { }
#endif


static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
        return addr >= start && addr < end;
}

static inline int
within_inclusive(unsigned long addr, unsigned long start, unsigned long end)
{
        return addr >= start && addr <= end;
}

#ifdef CONFIG_X86_64

static inline unsigned long highmap_start_pfn(void)
{
        return __pa_symbol(_text) >> PAGE_SHIFT;
}

static inline unsigned long highmap_end_pfn(void)
{
        /* Do not reference physical address outside the kernel. */
        return __pa_symbol(roundup(_brk_end, PMD_SIZE) - 1) >> PAGE_SHIFT;
}

static bool __cpa_pfn_in_highmap(unsigned long pfn)
{
        /*
         * Kernel text has an alias mapping at a high address, known
         * here as "highmap".
         */
        return within_inclusive(pfn, highmap_start_pfn(), highmap_end_pfn());
}

#else

static bool __cpa_pfn_in_highmap(unsigned long pfn)
{
        /* There is no highmap on 32-bit */
        return false;
}

#endif

/*
 * See set_mce_nospec().
 *
 * Machine check recovery code needs to change cache mode of poisoned pages to
 * UC to avoid speculative access logging another error. But passing the
 * address of the 1:1 mapping to set_memory_uc() is a fine way to encourage a
 * speculative access. So we cheat and flip the top bit of the address. This
 * works fine for the code that updates the page tables. But at the end of the
 * process we need to flush the TLB and cache and the non-canonical address
 * causes a #GP fault when used by the INVLPG and CLFLUSH instructions.
 *
 * But in the common case we already have a canonical address. This code
 * will fix the top bit if needed and is a no-op otherwise.
 */
static inline unsigned long fix_addr(unsigned long addr)
{
#ifdef CONFIG_X86_64
        return (long)(addr << 1) >> 1;
#else
        return addr;
#endif
}

static unsigned long __cpa_addr(struct cpa_data *cpa, unsigned long idx)
{
        if (cpa->flags & CPA_PAGES_ARRAY) {
                struct page *page = cpa->pages[idx];

                if (unlikely(PageHighMem(page)))
                        return 0;

                return (unsigned long)page_address(page);
        }

        if (cpa->flags & CPA_ARRAY)
                return cpa->vaddr[idx];

        return *cpa->vaddr + idx * PAGE_SIZE;
}

/*
 * Flushing functions
 */

static void clflush_cache_range_opt(void *vaddr, unsigned int size)
{
        const unsigned long clflush_size = boot_cpu_data.x86_clflush_size;
        void *p = (void *)((unsigned long)vaddr & ~(clflush_size - 1));
        void *vend = vaddr + size;

        if (p >= vend)
                return;

        for (; p < vend; p += clflush_size)
                clflushopt(p);
}

/**
 * clflush_cache_range - flush a cache range with clflush
 * @vaddr:      virtual start address
 * @size:       number of bytes to flush
 *
 * CLFLUSHOPT is an unordered instruction which needs fencing with MFENCE or
 * SFENCE to avoid ordering issues.
 */
void clflush_cache_range(void *vaddr, unsigned int size)
{
        mb();
        clflush_cache_range_opt(vaddr, size);
        mb();
}
EXPORT_SYMBOL_GPL(clflush_cache_range);

#ifdef CONFIG_ARCH_HAS_PMEM_API
void arch_invalidate_pmem(void *addr, size_t size)
{
        clflush_cache_range(addr, size);
}
EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
#endif

static void __cpa_flush_all(void *arg)
{
        unsigned long cache = (unsigned long)arg;

        /*
         * Flush all to work around Errata in early athlons regarding
         * large page flushing.
         */
        __flush_tlb_all();

        if (cache && boot_cpu_data.x86 >= 4)
                wbinvd();
}

static void cpa_flush_all(unsigned long cache)
{
        BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

        on_each_cpu(__cpa_flush_all, (void *) cache, 1);
}

static void __cpa_flush_tlb(void *data)
{
        struct cpa_data *cpa = data;
        unsigned int i;

        for (i = 0; i < cpa->numpages; i++)
                flush_tlb_one_kernel(fix_addr(__cpa_addr(cpa, i)));
}

static void cpa_flush(struct cpa_data *data, int cache)
{
        struct cpa_data *cpa = data;
        unsigned int i;

        BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

        if (cache && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
                cpa_flush_all(cache);
                return;
        }

        if (cpa->force_flush_all || cpa->numpages > tlb_single_page_flush_ceiling)
                flush_tlb_all();
        else
                on_each_cpu(__cpa_flush_tlb, cpa, 1);

        if (!cache)
                return;

        mb();
        for (i = 0; i < cpa->numpages; i++) {
                unsigned long addr = __cpa_addr(cpa, i);
                unsigned int level;

                pte_t *pte = lookup_address(addr, &level);

                /*
                 * Only flush present addresses:
                 */
                if (pte && (pte_val(*pte) & _PAGE_PRESENT))
                        clflush_cache_range_opt((void *)fix_addr(addr), PAGE_SIZE);
        }
        mb();
}

static bool overlaps(unsigned long r1_start, unsigned long r1_end,
                     unsigned long r2_start, unsigned long r2_end)
{
        return (r1_start <= r2_end && r1_end >= r2_start) ||
                (r2_start <= r1_end && r2_end >= r1_start);
}

#ifdef CONFIG_PCI_BIOS
/*
 * The BIOS area between 640k and 1Mb needs to be executable for PCI BIOS
 * based config access (CONFIG_PCI_GOBIOS) support.
 */
#define BIOS_PFN        PFN_DOWN(BIOS_BEGIN)
#define BIOS_PFN_END    PFN_DOWN(BIOS_END - 1)

static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
{
        if (pcibios_enabled && overlaps(spfn, epfn, BIOS_PFN, BIOS_PFN_END))
                return _PAGE_NX;
        return 0;
}
#else
static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
{
        return 0;
}
#endif

/*
 * The .rodata section needs to be read-only. Using the pfn catches all
 * aliases.  This also includes __ro_after_init, so do not enforce until
 * kernel_set_to_readonly is true.
 */
static pgprotval_t protect_rodata(unsigned long spfn, unsigned long epfn)
{
        unsigned long epfn_ro, spfn_ro = PFN_DOWN(__pa_symbol(__start_rodata));

        /*
         * Note: __end_rodata is at page aligned and not inclusive, so
         * subtract 1 to get the last enforced PFN in the rodata area.
         */
        epfn_ro = PFN_DOWN(__pa_symbol(__end_rodata)) - 1;

        if (kernel_set_to_readonly && overlaps(spfn, epfn, spfn_ro, epfn_ro))
                return _PAGE_RW;
        return 0;
}

/*
 * Protect kernel text against becoming non executable by forbidding
 * _PAGE_NX.  This protects only the high kernel mapping (_text -> _etext)
 * out of which the kernel actually executes.  Do not protect the low
 * mapping.
 *
 * This does not cover __inittext since that is gone after boot.
 */
static pgprotval_t protect_kernel_text(unsigned long start, unsigned long end)
{
        unsigned long t_end = (unsigned long)_etext - 1;
        unsigned long t_start = (unsigned long)_text;

        if (overlaps(start, end, t_start, t_end))
                return _PAGE_NX;
        return 0;
}

#if defined(CONFIG_X86_64)
/*
 * Once the kernel maps the text as RO (kernel_set_to_readonly is set),
 * kernel text mappings for the large page aligned text, rodata sections
 * will be always read-only. For the kernel identity mappings covering the
 * holes caused by this alignment can be anything that user asks.
 *
 * This will preserve the large page mappings for kernel text/data at no
 * extra cost.
 */
static pgprotval_t protect_kernel_text_ro(unsigned long start,
                                          unsigned long end)
{
        unsigned long t_end = (unsigned long)__end_rodata_hpage_align - 1;
        unsigned long t_start = (unsigned long)_text;
        unsigned int level;

        if (!kernel_set_to_readonly || !overlaps(start, end, t_start, t_end))
                return 0;
        /*
         * Don't enforce the !RW mapping for the kernel text mapping, if
         * the current mapping is already using small page mapping.  No
         * need to work hard to preserve large page mappings in this case.
         *
         * This also fixes the Linux Xen paravirt guest boot failure caused
         * by unexpected read-only mappings for kernel identity
         * mappings. In this paravirt guest case, the kernel text mapping
         * and the kernel identity mapping share the same page-table pages,
         * so the protections for kernel text and identity mappings have to
         * be the same.
         */
        if (lookup_address(start, &level) && (level != PG_LEVEL_4K))
                return _PAGE_RW;
        return 0;
}
#else
static pgprotval_t protect_kernel_text_ro(unsigned long start,
                                          unsigned long end)
{
        return 0;
}
#endif

static inline bool conflicts(pgprot_t prot, pgprotval_t val)
{
        return (pgprot_val(prot) & ~val) != pgprot_val(prot);
}

static inline void check_conflict(int warnlvl, pgprot_t prot, pgprotval_t val,
                                  unsigned long start, unsigned long end,
                                  unsigned long pfn, const char *txt)
{
        static const char *lvltxt[] = {
                [CPA_CONFLICT]  = "conflict",
                [CPA_PROTECT]   = "protect",
                [CPA_DETECT]    = "detect",
        };

        if (warnlvl > cpa_warn_level || !conflicts(prot, val))
                return;

        pr_warn("CPA %8s %10s: 0x%016lx - 0x%016lx PFN %lx req %016llx prevent %016llx\n",
                lvltxt[warnlvl], txt, start, end, pfn, (unsigned long long)pgprot_val(prot),
                (unsigned long long)val);
}

/*
 * Certain areas of memory on x86 require very specific protection flags,
 * for example the BIOS area or kernel text. Callers don't always get this
 * right (again, ioremap() on BIOS memory is not uncommon) so this function
 * checks and fixes these known static required protection bits.
 */
static inline pgprot_t static_protections(pgprot_t prot, unsigned long start,
                                          unsigned long pfn, unsigned long npg,
                                          unsigned long lpsize, int warnlvl)
{
        pgprotval_t forbidden, res;
        unsigned long end;

        /*
         * There is no point in checking RW/NX conflicts when the requested
         * mapping is setting the page !PRESENT.
         */
        if (!(pgprot_val(prot) & _PAGE_PRESENT))
                return prot;

        /* Operate on the virtual address */
        end = start + npg * PAGE_SIZE - 1;

        res = protect_kernel_text(start, end);
        check_conflict(warnlvl, prot, res, start, end, pfn, "Text NX");
        forbidden = res;

        /*
         * Special case to preserve a large page. If the change spawns the
         * full large page mapping then there is no point to split it
         * up. Happens with ftrace and is going to be removed once ftrace
         * switched to text_poke().
         */
        if (lpsize != (npg * PAGE_SIZE) || (start & (lpsize - 1))) {
                res = protect_kernel_text_ro(start, end);
                check_conflict(warnlvl, prot, res, start, end, pfn, "Text RO");
                forbidden |= res;
        }

        /* Check the PFN directly */
        res = protect_pci_bios(pfn, pfn + npg - 1);
        check_conflict(warnlvl, prot, res, start, end, pfn, "PCIBIOS NX");
        forbidden |= res;

        res = protect_rodata(pfn, pfn + npg - 1);
        check_conflict(warnlvl, prot, res, start, end, pfn, "Rodata RO");
        forbidden |= res;

        return __pgprot(pgprot_val(prot) & ~forbidden);
}

/*
 * Lookup the page table entry for a virtual address in a specific pgd.
 * Return a pointer to the entry and the level of the mapping.
 */
pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address,
                             unsigned int *level)
{
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;

        *level = PG_LEVEL_NONE;

        if (pgd_none(*pgd))
                return NULL;

        p4d = p4d_offset(pgd, address);
        if (p4d_none(*p4d))
                return NULL;

        *level = PG_LEVEL_512G;
        if (p4d_large(*p4d) || !p4d_present(*p4d))
                return (pte_t *)p4d;

        pud = pud_offset(p4d, address);
        if (pud_none(*pud))
                return NULL;

        *level = PG_LEVEL_1G;
        if (pud_large(*pud) || !pud_present(*pud))
                return (pte_t *)pud;

        pmd = pmd_offset(pud, address);
        if (pmd_none(*pmd))
                return NULL;

        *level = PG_LEVEL_2M;
        if (pmd_large(*pmd) || !pmd_present(*pmd))
                return (pte_t *)pmd;

        *level = PG_LEVEL_4K;

        return pte_offset_kernel(pmd, address);
}

/*
 * Lookup the page table entry for a virtual address. Return a pointer
 * to the entry and the level of the mapping.
 *
 * Note: We return pud and pmd either when the entry is marked large
 * or when the present bit is not set. Otherwise we would return a
 * pointer to a nonexisting mapping.
 */
pte_t *lookup_address(unsigned long address, unsigned int *level)
{
        return lookup_address_in_pgd(pgd_offset_k(address), address, level);
}
EXPORT_SYMBOL_GPL(lookup_address);

/*
 * Lookup the page table entry for a virtual address in a given mm. Return a
 * pointer to the entry and the level of the mapping.
 */
pte_t *lookup_address_in_mm(struct mm_struct *mm, unsigned long address,
                            unsigned int *level)
{
        return lookup_address_in_pgd(pgd_offset(mm, address), address, level);
}
EXPORT_SYMBOL_GPL(lookup_address_in_mm);

static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
                                  unsigned int *level)
{
        if (cpa->pgd)
                return lookup_address_in_pgd(cpa->pgd + pgd_index(address),
                                               address, level);

        return lookup_address(address, level);
}

/*
 * Lookup the PMD entry for a virtual address. Return a pointer to the entry
 * or NULL if not present.
 */
pmd_t *lookup_pmd_address(unsigned long address)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;

        pgd = pgd_offset_k(address);
        if (pgd_none(*pgd))
                return NULL;

        p4d = p4d_offset(pgd, address);
        if (p4d_none(*p4d) || p4d_large(*p4d) || !p4d_present(*p4d))
                return NULL;

        pud = pud_offset(p4d, address);
        if (pud_none(*pud) || pud_large(*pud) || !pud_present(*pud))
                return NULL;

        return pmd_offset(pud, address);
}

/*
 * This is necessary because __pa() does not work on some
 * kinds of memory, like vmalloc() or the alloc_remap()
 * areas on 32-bit NUMA systems.  The percpu areas can
 * end up in this kind of memory, for instance.
 *
 * This could be optimized, but it is only intended to be
 * used at initialization time, and keeping it
 * unoptimized should increase the testing coverage for
 * the more obscure platforms.
 */
phys_addr_t slow_virt_to_phys(void *__virt_addr)
{
        unsigned long virt_addr = (unsigned long)__virt_addr;
        phys_addr_t phys_addr;
        unsigned long offset;
        enum pg_level level;
        pte_t *pte;

        pte = lookup_address(virt_addr, &level);
        BUG_ON(!pte);

        /*
         * pXX_pfn() returns unsigned long, which must be cast to phys_addr_t
         * before being left-shifted PAGE_SHIFT bits -- this trick is to
         * make 32-PAE kernel work correctly.
         */
        switch (level) {
        case PG_LEVEL_1G:
                phys_addr = (phys_addr_t)pud_pfn(*(pud_t *)pte) << PAGE_SHIFT;
                offset = virt_addr & ~PUD_PAGE_MASK;
                break;
        case PG_LEVEL_2M:
                phys_addr = (phys_addr_t)pmd_pfn(*(pmd_t *)pte) << PAGE_SHIFT;
                offset = virt_addr & ~PMD_PAGE_MASK;
                break;
        default:
                phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
                offset = virt_addr & ~PAGE_MASK;
        }

        return (phys_addr_t)(phys_addr | offset);
}
EXPORT_SYMBOL_GPL(slow_virt_to_phys);

/*
 * Set the new pmd in all the pgds we know about:
 */
static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
        /* change init_mm */
        set_pte_atomic(kpte, pte);
#ifdef CONFIG_X86_32
        if (!SHARED_KERNEL_PMD) {
                struct page *page;

                list_for_each_entry(page, &pgd_list, lru) {
                        pgd_t *pgd;
                        p4d_t *p4d;
                        pud_t *pud;
                        pmd_t *pmd;

                        pgd = (pgd_t *)page_address(page) + pgd_index(address);
                        p4d = p4d_offset(pgd, address);
                        pud = pud_offset(p4d, address);
                        pmd = pmd_offset(pud, address);
                        set_pte_atomic((pte_t *)pmd, pte);
                }
        }
#endif
}

static pgprot_t pgprot_clear_protnone_bits(pgprot_t prot)
{
        /*
         * _PAGE_GLOBAL means "global page" for present PTEs.
         * But, it is also used to indicate _PAGE_PROTNONE
         * for non-present PTEs.
         *
         * This ensures that a _PAGE_GLOBAL PTE going from
         * present to non-present is not confused as
         * _PAGE_PROTNONE.
         */
        if (!(pgprot_val(prot) & _PAGE_PRESENT))
                pgprot_val(prot) &= ~_PAGE_GLOBAL;

        return prot;
}

static int __should_split_large_page(pte_t *kpte, unsigned long address,
                                     struct cpa_data *cpa)
{
        unsigned long numpages, pmask, psize, lpaddr, pfn, old_pfn;
        pgprot_t old_prot, new_prot, req_prot, chk_prot;
        pte_t new_pte, *tmp;
        enum pg_level level;

        /*
         * Check for races, another CPU might have split this page
         * up already:
         */
        tmp = _lookup_address_cpa(cpa, address, &level);
        if (tmp != kpte)
                return 1;

        switch (level) {
        case PG_LEVEL_2M:
                old_prot = pmd_pgprot(*(pmd_t *)kpte);
                old_pfn = pmd_pfn(*(pmd_t *)kpte);
                cpa_inc_2m_checked();
                break;
        case PG_LEVEL_1G:
                old_prot = pud_pgprot(*(pud_t *)kpte);
                old_pfn = pud_pfn(*(pud_t *)kpte);
                cpa_inc_1g_checked();
                break;
        default:
                return -EINVAL;
        }

        psize = page_level_size(level);
        pmask = page_level_mask(level);

        /*
         * Calculate the number of pages, which fit into this large
         * page starting at address:
         */
        lpaddr = (address + psize) & pmask;
        numpages = (lpaddr - address) >> PAGE_SHIFT;
        if (numpages < cpa->numpages)
                cpa->numpages = numpages;

        /*
         * We are safe now. Check whether the new pgprot is the same:
         * Convert protection attributes to 4k-format, as cpa->mask* are set
         * up accordingly.
         */

        /* Clear PSE (aka _PAGE_PAT) and move PAT bit to correct position */
        req_prot = pgprot_large_2_4k(old_prot);

        pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr);
        pgprot_val(req_prot) |= pgprot_val(cpa->mask_set);

        /*
         * req_prot is in format of 4k pages. It must be converted to large
         * page format: the caching mode includes the PAT bit located at
         * different bit positions in the two formats.
         */
        req_prot = pgprot_4k_2_large(req_prot);
        req_prot = pgprot_clear_protnone_bits(req_prot);
        if (pgprot_val(req_prot) & _PAGE_PRESENT)
                pgprot_val(req_prot) |= _PAGE_PSE;

        /*
         * old_pfn points to the large page base pfn. So we need to add the
         * offset of the virtual address:
         */
        pfn = old_pfn + ((address & (psize - 1)) >> PAGE_SHIFT);
        cpa->pfn = pfn;

        /*
         * Calculate the large page base address and the number of 4K pages
         * in the large page
         */
        lpaddr = address & pmask;
        numpages = psize >> PAGE_SHIFT;

        /*
         * Sanity check that the existing mapping is correct versus the static
         * protections. static_protections() guards against !PRESENT, so no
         * extra conditional required here.
         */
        chk_prot = static_protections(old_prot, lpaddr, old_pfn, numpages,
                                      psize, CPA_CONFLICT);

        if (WARN_ON_ONCE(pgprot_val(chk_prot) != pgprot_val(old_prot))) {
                /*
                 * Split the large page and tell the split code to
                 * enforce static protections.
                 */
                cpa->force_static_prot = 1;
                return 1;
        }

        /*
         * Optimization: If the requested pgprot is the same as the current
         * pgprot, then the large page can be preserved and no updates are
         * required independent of alignment and length of the requested
         * range. The above already established that the current pgprot is
         * correct, which in consequence makes the requested pgprot correct
         * as well if it is the same. The static protection scan below will
         * not come to a different conclusion.
         */
        if (pgprot_val(req_prot) == pgprot_val(old_prot)) {
                cpa_inc_lp_sameprot(level);
                return 0;
        }

        /*
         * If the requested range does not cover the full page, split it up
         */
        if (address != lpaddr || cpa->numpages != numpages)
                return 1;

        /*
         * Check whether the requested pgprot is conflicting with a static
         * protection requirement in the large page.
         */
        new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages,
                                      psize, CPA_DETECT);

        /*
         * If there is a conflict, split the large page.
         *
         * There used to be a 4k wise evaluation trying really hard to
         * preserve the large pages, but experimentation has shown, that this
         * does not help at all. There might be corner cases which would
         * preserve one large page occasionally, but it's really not worth the
         * extra code and cycles for the common case.
         */
        if (pgprot_val(req_prot) != pgprot_val(new_prot))
                return 1;

        /* All checks passed. Update the large page mapping. */
        new_pte = pfn_pte(old_pfn, new_prot);
        __set_pmd_pte(kpte, address, new_pte);
        cpa->flags |= CPA_FLUSHTLB;
        cpa_inc_lp_preserved(level);
        return 0;
}

static int should_split_large_page(pte_t *kpte, unsigned long address,
                                   struct cpa_data *cpa)
{
        int do_split;

        if (cpa->force_split)
                return 1;

        spin_lock(&pgd_lock);
        do_split = __should_split_large_page(kpte, address, cpa);
        spin_unlock(&pgd_lock);

        return do_split;
}

static void split_set_pte(struct cpa_data *cpa, pte_t *pte, unsigned long pfn,
                          pgprot_t ref_prot, unsigned long address,
                          unsigned long size)
{
        unsigned int npg = PFN_DOWN(size);
        pgprot_t prot;

        /*
         * If should_split_large_page() discovered an inconsistent mapping,
         * remove the invalid protection in the split mapping.
         */
        if (!cpa->force_static_prot)
                goto set;

        /* Hand in lpsize = 0 to enforce the protection mechanism */
        prot = static_protections(ref_prot, address, pfn, npg, 0, CPA_PROTECT);

        if (pgprot_val(prot) == pgprot_val(ref_prot))
                goto set;

        /*
         * If this is splitting a PMD, fix it up. PUD splits cannot be
         * fixed trivially as that would require to rescan the newly
         * installed PMD mappings after returning from split_large_page()
         * so an eventual further split can allocate the necessary PTE
         * pages. Warn for now and revisit it in case this actually
         * happens.
         */
        if (size == PAGE_SIZE)
                ref_prot = prot;
        else
                pr_warn_once("CPA: Cannot fixup static protections for PUD split\n");
set:
        set_pte(pte, pfn_pte(pfn, ref_prot));
}

static int
__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
                   struct page *base)
{
        unsigned long lpaddr, lpinc, ref_pfn, pfn, pfninc = 1;
        pte_t *pbase = (pte_t *)page_address(base);
        unsigned int i, level;
        pgprot_t ref_prot;
        pte_t *tmp;

        spin_lock(&pgd_lock);
        /*
         * Check for races, another CPU might have split this page
         * up for us already:
         */
        tmp = _lookup_address_cpa(cpa, address, &level);
        if (tmp != kpte) {
                spin_unlock(&pgd_lock);
                return 1;
        }

        paravirt_alloc_pte(&init_mm, page_to_pfn(base));

        switch (level) {
        case PG_LEVEL_2M:
                ref_prot = pmd_pgprot(*(pmd_t *)kpte);
                /*
                 * Clear PSE (aka _PAGE_PAT) and move
                 * PAT bit to correct position.
                 */
                ref_prot = pgprot_large_2_4k(ref_prot);
                ref_pfn = pmd_pfn(*(pmd_t *)kpte);
                lpaddr = address & PMD_MASK;
                lpinc = PAGE_SIZE;

                break;

        case PG_LEVEL_1G:
                ref_prot = pud_pgprot(*(pud_t *)kpte);
                ref_pfn = pud_pfn(*(pud_t *)kpte);
                pfninc = PMD_PAGE_SIZE >> PAGE_SHIFT;
                lpaddr = address & PUD_MASK;
                lpinc = PMD_SIZE;
                /*
                 * Clear the PSE flags if the PRESENT flag is not set
                 * otherwise pmd_present/pmd_huge will return true
                 * even on a non present pmd.
                 */
                if (!(pgprot_val(ref_prot) & _PAGE_PRESENT))
                        pgprot_val(ref_prot) &= ~_PAGE_PSE;
                break;

        default:
                spin_unlock(&pgd_lock);
                return 1;
        }

        ref_prot = pgprot_clear_protnone_bits(ref_prot);

        /*
         * Get the target pfn from the original entry:
         */
        pfn = ref_pfn;
        for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc, lpaddr += lpinc)
                split_set_pte(cpa, pbase + i, pfn, ref_prot, lpaddr, lpinc);

        if (virt_addr_valid(address)) {
                unsigned long pfn = PFN_DOWN(__pa(address));

                if (pfn_range_is_mapped(pfn, pfn + 1))
                        split_page_count(level);
        }

        /*
         * Install the new, split up pagetable.
         *
         * We use the standard kernel pagetable protections for the new
         * pagetable protections, the actual ptes set above control the
         * primary protection behavior:
         */
        __set_pmd_pte(kpte, address, mk_pte(base, __pgprot(_KERNPG_TABLE)));

        /*
         * Do a global flush tlb after splitting the large page
         * and before we do the actual change page attribute in the PTE.
         *
         * Without this, we violate the TLB application note, that says:
         * "The TLBs may contain both ordinary and large-page
         *  translations for a 4-KByte range of linear addresses. This
         *  may occur if software modifies the paging structures so that
         *  the page size used for the address range changes. If the two
         *  translations differ with respect to page frame or attributes
         *  (e.g., permissions), processor behavior is undefined and may
         *  be implementation-specific."
         *
         * We do this global tlb flush inside the cpa_lock, so that we
         * don't allow any other cpu, with stale tlb entries change the
         * page attribute in parallel, that also falls into the
         * just split large page entry.
         */
        flush_tlb_all();
        spin_unlock(&pgd_lock);

        return 0;
}

static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
                            unsigned long address)
{
        struct page *base;

        if (!debug_pagealloc_enabled())
                spin_unlock(&cpa_lock);
        base = alloc_pages(GFP_KERNEL, 0);
        if (!debug_pagealloc_enabled())
                spin_lock(&cpa_lock);
        if (!base)
                return -ENOMEM;

        if (__split_large_page(cpa, kpte, address, base))
                __free_page(base);

        return 0;
}

static bool try_to_free_pte_page(pte_t *pte)
{
        int i;

        for (i = 0; i < PTRS_PER_PTE; i++)
                if (!pte_none(pte[i]))
                        return false;

        free_page((unsigned long)pte);
        return true;
}

static bool try_to_free_pmd_page(pmd_t *pmd)
{
        int i;

        for (i = 0; i < PTRS_PER_PMD; i++)
                if (!pmd_none(pmd[i]))
                        return false;

        free_page((unsigned long)pmd);
        return true;
}

static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end)
{
        pte_t *pte = pte_offset_kernel(pmd, start);

        while (start < end) {
                set_pte(pte, __pte(0));

                start += PAGE_SIZE;
                pte++;
        }

        if (try_to_free_pte_page((pte_t *)pmd_page_vaddr(*pmd))) {
                pmd_clear(pmd);
                return true;
        }
        return false;
}

static void __unmap_pmd_range(pud_t *pud, pmd_t *pmd,
                              unsigned long start, unsigned long end)
{
        if (unmap_pte_range(pmd, start, end))
                if (try_to_free_pmd_page(pud_pgtable(*pud)))
                        pud_clear(pud);
}

static void unmap_pmd_range(pud_t *pud, unsigned long start, unsigned long end)
{
        pmd_t *pmd = pmd_offset(pud, start);

        /*
         * Not on a 2MB page boundary?
         */
        if (start & (PMD_SIZE - 1)) {
                unsigned long next_page = (start + PMD_SIZE) & PMD_MASK;
                unsigned long pre_end = min_t(unsigned long, end, next_page);

                __unmap_pmd_range(pud, pmd, start, pre_end);

                start = pre_end;
                pmd++;
        }

        /*
         * Try to unmap in 2M chunks.
         */
        while (end - start >= PMD_SIZE) {
                if (pmd_large(*pmd))
                        pmd_clear(pmd);
                else
                        __unmap_pmd_range(pud, pmd, start, start + PMD_SIZE);

                start += PMD_SIZE;
                pmd++;
        }

        /*
         * 4K leftovers?
         */
        if (start < end)
                return __unmap_pmd_range(pud, pmd, start, end);

        /*
         * Try again to free the PMD page if haven't succeeded above.
         */
        if (!pud_none(*pud))
                if (try_to_free_pmd_page(pud_pgtable(*pud)))
                        pud_clear(pud);
}

static void unmap_pud_range(p4d_t *p4d, unsigned long start, unsigned long end)
{
        pud_t *pud = pud_offset(p4d, start);

        /*
         * Not on a GB page boundary?
         */
        if (start & (PUD_SIZE - 1)) {
                unsigned long next_page = (start + PUD_SIZE) & PUD_MASK;
                unsigned long pre_end   = min_t(unsigned long, end, next_page);

                unmap_pmd_range(pud, start, pre_end);

                start = pre_end;
                pud++;
        }

        /*
         * Try to unmap in 1G chunks?
         */
        while (end - start >= PUD_SIZE) {

                if (pud_large(*pud))
                        pud_clear(pud);
                else
                        unmap_pmd_range(pud, start, start + PUD_SIZE);

                start += PUD_SIZE;
                pud++;
        }

        /*
         * 2M leftovers?
         */
        if (start < end)
                unmap_pmd_range(pud, start, end);

        /*
         * No need to try to free the PUD page because we'll free it in
         * populate_pgd's error path
         */
}

static int alloc_pte_page(pmd_t *pmd)
{
        pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
        if (!pte)
                return -1;

        set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
        return 0;
}

static int alloc_pmd_page(pud_t *pud)
{
        pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
        if (!pmd)
                return -1;

        set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
        return 0;
}

static void populate_pte(struct cpa_data *cpa,
                         unsigned long start, unsigned long end,
                         unsigned num_pages, pmd_t *pmd, pgprot_t pgprot)
{
        pte_t *pte;

        pte = pte_offset_kernel(pmd, start);

        pgprot = pgprot_clear_protnone_bits(pgprot);

        while (num_pages-- && start < end) {
                set_pte(pte, pfn_pte(cpa->pfn, pgprot));

                start    += PAGE_SIZE;
                cpa->pfn++;
                pte++;
        }
}

static long populate_pmd(struct cpa_data *cpa,
                         unsigned long start, unsigned long end,
                         unsigned num_pages, pud_t *pud, pgprot_t pgprot)
{
        long cur_pages = 0;
        pmd_t *pmd;
        pgprot_t pmd_pgprot;

        /*
         * Not on a 2M boundary?
         */
        if (start & (PMD_SIZE - 1)) {
                unsigned long pre_end = start + (num_pages << PAGE_SHIFT);
                unsigned long next_page = (start + PMD_SIZE) & PMD_MASK;

                pre_end   = min_t(unsigned long, pre_end, next_page);
                cur_pages = (pre_end - start) >> PAGE_SHIFT;
                cur_pages = min_t(unsigned int, num_pages, cur_pages);

                /*
                 * Need a PTE page?
                 */
                pmd = pmd_offset(pud, start);
                if (pmd_none(*pmd))
                        if (alloc_pte_page(pmd))
                                return -1;

                populate_pte(cpa, start, pre_end, cur_pages, pmd, pgprot);

                start = pre_end;
        }

        /*
         * We mapped them all?
         */
        if (num_pages == cur_pages)
                return cur_pages;

        pmd_pgprot = pgprot_4k_2_large(pgprot);

        while (end - start >= PMD_SIZE) {

                /*
                 * We cannot use a 1G page so allocate a PMD page if needed.
                 */
                if (pud_none(*pud))
                        if (alloc_pmd_page(pud))
                                return -1;

                pmd = pmd_offset(pud, start);

                set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn,
                                        canon_pgprot(pmd_pgprot))));

                start     += PMD_SIZE;
                cpa->pfn  += PMD_SIZE >> PAGE_SHIFT;
                cur_pages += PMD_SIZE >> PAGE_SHIFT;
        }

        /*
         * Map trailing 4K pages.
         */
        if (start < end) {
                pmd = pmd_offset(pud, start);
                if (pmd_none(*pmd))
                        if (alloc_pte_page(pmd))
                                return -1;

                populate_pte(cpa, start, end, num_pages - cur_pages,
                             pmd, pgprot);
        }
        return num_pages;
}

static int populate_pud(struct cpa_data *cpa, unsigned long start, p4d_t *p4d,
                        pgprot_t pgprot)
{
        pud_t *pud;
        unsigned long end;
        long cur_pages = 0;
        pgprot_t pud_pgprot;

        end = start + (cpa->numpages << PAGE_SHIFT);

        /*
         * Not on a Gb page boundary? => map everything up to it with
         * smaller pages.
         */
        if (start & (PUD_SIZE - 1)) {
                unsigned long pre_end;
                unsigned long next_page = (start + PUD_SIZE) & PUD_MASK;

                pre_end   = min_t(unsigned long, end, next_page);
                cur_pages = (pre_end - start) >> PAGE_SHIFT;
                cur_pages = min_t(int, (int)cpa->numpages, cur_pages);

                pud = pud_offset(p4d, start);

                /*
                 * Need a PMD page?
                 */
                if (pud_none(*pud))
                        if (alloc_pmd_page(pud))
                                return -1;

                cur_pages = populate_pmd(cpa, start, pre_end, cur_pages,
                                         pud, pgprot);
                if (cur_pages < 0)
                        return cur_pages;

                start = pre_end;
        }

        /* We mapped them all? */
        if (cpa->numpages == cur_pages)
                return cur_pages;

        pud = pud_offset(p4d, start);
        pud_pgprot = pgprot_4k_2_large(pgprot);

        /*
         * Map everything starting from the Gb boundary, possibly with 1G pages
         */
        while (boot_cpu_has(X86_FEATURE_GBPAGES) && end - start >= PUD_SIZE) {
                set_pud(pud, pud_mkhuge(pfn_pud(cpa->pfn,
                                   canon_pgprot(pud_pgprot))));

                start     += PUD_SIZE;
                cpa->pfn  += PUD_SIZE >> PAGE_SHIFT;
                cur_pages += PUD_SIZE >> PAGE_SHIFT;
                pud++;
        }

        /* Map trailing leftover */
        if (start < end) {
                long tmp;

                pud = pud_offset(p4d, start);
                if (pud_none(*pud))
                        if (alloc_pmd_page(pud))
                                return -1;

                tmp = populate_pmd(cpa, start, end, cpa->numpages - cur_pages,
                                   pud, pgprot);
                if (tmp < 0)
                        return cur_pages;

                cur_pages += tmp;
        }
        return cur_pages;
}

/*
 * Restrictions for kernel page table do not necessarily apply when mapping in
 * an alternate PGD.
 */
static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
{
        pgprot_t pgprot = __pgprot(_KERNPG_TABLE);
        pud_t *pud = NULL;      /* shut up gcc */
        p4d_t *p4d;
        pgd_t *pgd_entry;
        long ret;

        pgd_entry = cpa->pgd + pgd_index(addr);

        if (pgd_none(*pgd_entry)) {
                p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
                if (!p4d)
                        return -1;

                set_pgd(pgd_entry, __pgd(__pa(p4d) | _KERNPG_TABLE));
        }

        /*
         * Allocate a PUD page and hand it down for mapping.
         */
        p4d = p4d_offset(pgd_entry, addr);
        if (p4d_none(*p4d)) {
                pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
                if (!pud)
                        return -1;

                set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
        }

        pgprot_val(pgprot) &= ~pgprot_val(cpa->mask_clr);
        pgprot_val(pgprot) |=  pgprot_val(cpa->mask_set);

        ret = populate_pud(cpa, addr, p4d, pgprot);
        if (ret < 0) {
                /*
                 * Leave the PUD page in place in case some other CPU or thread
                 * already found it, but remove any useless entries we just
                 * added to it.
                 */
                unmap_pud_range(p4d, addr,
                                addr + (cpa->numpages << PAGE_SHIFT));
                return ret;
        }

        cpa->numpages = ret;
        return 0;
}

static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
                               int primary)
{
        if (cpa->pgd) {
                /*
                 * Right now, we only execute this code path when mapping
                 * the EFI virtual memory map regions, no other users
                 * provide a ->pgd value. This may change in the future.
                 */
                return populate_pgd(cpa, vaddr);
        }

        /*
         * Ignore all non primary paths.
         */
        if (!primary) {
                cpa->numpages = 1;
                return 0;
        }

        /*
         * Ignore the NULL PTE for kernel identity mapping, as it is expected
         * to have holes.
         * Also set numpages to '1' indicating that we processed cpa req for
         * one virtual address page and its pfn. TBD: numpages can be set based
         * on the initial value and the level returned by lookup_address().
         */
        if (within(vaddr, PAGE_OFFSET,
                   PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT))) {
                cpa->numpages = 1;
                cpa->pfn = __pa(vaddr) >> PAGE_SHIFT;
                return 0;

        } else if (__cpa_pfn_in_highmap(cpa->pfn)) {
                /* Faults in the highmap are OK, so do not warn: */
                return -EFAULT;
        } else {
                WARN(1, KERN_WARNING "CPA: called for zero pte. "
                        "vaddr = %lx cpa->vaddr = %lx\n", vaddr,
                        *cpa->vaddr);

                return -EFAULT;
        }
}

static int __change_page_attr(struct cpa_data *cpa, int primary)
{
        unsigned long address;
        int do_split, err;
        unsigned int level;
        pte_t *kpte, old_pte;

        address = __cpa_addr(cpa, cpa->curpage);
repeat:
        kpte = _lookup_address_cpa(cpa, address, &level);
        if (!kpte)
                return __cpa_process_fault(cpa, address, primary);

        old_pte = *kpte;
        if (pte_none(old_pte))
                return __cpa_process_fault(cpa, address, primary);

        if (level == PG_LEVEL_4K) {
                pte_t new_pte;
                pgprot_t new_prot = pte_pgprot(old_pte);
                unsigned long pfn = pte_pfn(old_pte);

                pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
                pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);

                cpa_inc_4k_install();
                /* Hand in lpsize = 0 to enforce the protection mechanism */
                new_prot = static_protections(new_prot, address, pfn, 1, 0,
                                              CPA_PROTECT);

                new_prot = pgprot_clear_protnone_bits(new_prot);

                /*
                 * We need to keep the pfn from the existing PTE,
                 * after all we're only going to change it's attributes
                 * not the memory it points to
                 */
                new_pte = pfn_pte(pfn, new_prot);
                cpa->pfn = pfn;
                /*
                 * Do we really change anything ?
                 */
                if (pte_val(old_pte) != pte_val(new_pte)) {
                        set_pte_atomic(kpte, new_pte);
                        cpa->flags |= CPA_FLUSHTLB;
                }
                cpa->numpages = 1;
                return 0;
        }

        /*
         * Check, whether we can keep the large page intact
         * and just change the pte:
         */
        do_split = should_split_large_page(kpte, address, cpa);
        /*
         * When the range fits into the existing large page,
         * return. cp->numpages and cpa->tlbflush have been updated in
         * try_large_page:
         */
        if (do_split <= 0)
                return do_split;

        /*
         * We have to split the large page:
         */
        err = split_large_page(cpa, kpte, address);
        if (!err)
                goto repeat;

        return err;
}

static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias);

static int cpa_process_alias(struct cpa_data *cpa)
{
        struct cpa_data alias_cpa;
        unsigned long laddr = (unsigned long)__va(cpa->pfn << PAGE_SHIFT);
        unsigned long vaddr;
        int ret;

        if (!pfn_range_is_mapped(cpa->pfn, cpa->pfn + 1))
                return 0;

        /*
         * No need to redo, when the primary call touched the direct
         * mapping already:
         */
        vaddr = __cpa_addr(cpa, cpa->curpage);
        if (!(within(vaddr, PAGE_OFFSET,
                    PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT)))) {

                alias_cpa = *cpa;
                alias_cpa.vaddr = &laddr;
                alias_cpa.flags &= ~(CPA_PAGES_ARRAY | CPA_ARRAY);
                alias_cpa.curpage = 0;

                cpa->force_flush_all = 1;

                ret = __change_page_attr_set_clr(&alias_cpa, 0);
                if (ret)
                        return ret;
        }

#ifdef CONFIG_X86_64
        /*
         * If the primary call didn't touch the high mapping already
         * and the physical address is inside the kernel map, we need
         * to touch the high mapped kernel as well:
         */
        if (!within(vaddr, (unsigned long)_text, _brk_end) &&
            __cpa_pfn_in_highmap(cpa->pfn)) {
                unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) +
                                               __START_KERNEL_map - phys_base;
                alias_cpa = *cpa;
                alias_cpa.vaddr = &temp_cpa_vaddr;
                alias_cpa.flags &= ~(CPA_PAGES_ARRAY | CPA_ARRAY);
                alias_cpa.curpage = 0;

                cpa->force_flush_all = 1;
                /*
                 * The high mapping range is imprecise, so ignore the
                 * return value.
                 */
                __change_page_attr_set_clr(&alias_cpa, 0);
        }
#endif

        return 0;
}

static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
{
        unsigned long numpages = cpa->numpages;
        unsigned long rempages = numpages;
        int ret = 0;

        while (rempages) {
                /*
                 * Store the remaining nr of pages for the large page
                 * preservation check.
                 */
                cpa->numpages = rempages;
                /* for array changes, we can't use large page */
                if (cpa->flags & (CPA_ARRAY | CPA_PAGES_ARRAY))
                        cpa->numpages = 1;

                if (!debug_pagealloc_enabled())
                        spin_lock(&cpa_lock);
                ret = __change_page_attr(cpa, checkalias);
                if (!debug_pagealloc_enabled())
                        spin_unlock(&cpa_lock);
                if (ret)
                        goto out;

                if (checkalias) {
                        ret = cpa_process_alias(cpa);
                        if (ret)
                                goto out;
                }

                /*
                 * Adjust the number of pages with the result of the
                 * CPA operation. Either a large page has been
                 * preserved or a single page update happened.
                 */
                BUG_ON(cpa->numpages > rempages || !cpa->numpages);
                rempages -= cpa->numpages;
                cpa->curpage += cpa->numpages;
        }

out:
        /* Restore the original numpages */
        cpa->numpages = numpages;
        return ret;
}

static int change_page_attr_set_clr(unsigned long *addr, int numpages,
                                    pgprot_t mask_set, pgprot_t mask_clr,
                                    int force_split, int in_flag,
                                    struct page **pages)
{
        struct cpa_data cpa;
        int ret, cache, checkalias;

        memset(&cpa, 0, sizeof(cpa));

        /*
         * Check, if we are requested to set a not supported
         * feature.  Clearing non-supported features is OK.
         */
        mask_set = canon_pgprot(mask_set);

        if (!pgprot_val(mask_set) && !pgprot_val(mask_clr) && !force_split)
                return 0;

        /* Ensure we are PAGE_SIZE aligned */
        if (in_flag & CPA_ARRAY) {
                int i;
                for (i = 0; i < numpages; i++) {
                        if (addr[i] & ~PAGE_MASK) {
                                addr[i] &= PAGE_MASK;
                                WARN_ON_ONCE(1);
                        }
                }
        } else if (!(in_flag & CPA_PAGES_ARRAY)) {
                /*
                 * in_flag of CPA_PAGES_ARRAY implies it is aligned.
                 * No need to check in that case
                 */
                if (*addr & ~PAGE_MASK) {
                        *addr &= PAGE_MASK;
                        /*
                         * People should not be passing in unaligned addresses:
                         */
                        WARN_ON_ONCE(1);
                }
        }

        /* Must avoid aliasing mappings in the highmem code */
        kmap_flush_unused();

        vm_unmap_aliases();

        cpa.vaddr = addr;
        cpa.pages = pages;
        cpa.numpages = numpages;
        cpa.mask_set = mask_set;
        cpa.mask_clr = mask_clr;
        cpa.flags = 0;
        cpa.curpage = 0;
        cpa.force_split = force_split;

        if (in_flag & (CPA_ARRAY | CPA_PAGES_ARRAY))
                cpa.flags |= in_flag;

        /* No alias checking for _NX bit modifications */
        checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX;
        /* Has caller explicitly disabled alias checking? */
        if (in_flag & CPA_NO_CHECK_ALIAS)
                checkalias = 0;

        ret = __change_page_attr_set_clr(&cpa, checkalias);

        /*
         * Check whether we really changed something:
         */
        if (!(cpa.flags & CPA_FLUSHTLB))
                goto out;

        /*
         * No need to flush, when we did not set any of the caching
         * attributes:
         */
        cache = !!pgprot2cachemode(mask_set);

        /*
         * On error; flush everything to be sure.
         */
        if (ret) {
                cpa_flush_all(cache);
                goto out;
        }

        cpa_flush(&cpa, cache);
out:
        return ret;
}

static inline int change_page_attr_set(unsigned long *addr, int numpages,
                                       pgprot_t mask, int array)
{
        return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0), 0,
                (array ? CPA_ARRAY : 0), NULL);
}

static inline int change_page_attr_clear(unsigned long *addr, int numpages,
                                         pgprot_t mask, int array)
{
        return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask, 0,
                (array ? CPA_ARRAY : 0), NULL);
}

static inline int cpa_set_pages_array(struct page **pages, int numpages,
                                       pgprot_t mask)
{
        return change_page_attr_set_clr(NULL, numpages, mask, __pgprot(0), 0,
                CPA_PAGES_ARRAY, pages);
}

static inline int cpa_clear_pages_array(struct page **pages, int numpages,
                                         pgprot_t mask)
{
        return change_page_attr_set_clr(NULL, numpages, __pgprot(0), mask, 0,
                CPA_PAGES_ARRAY, pages);
}

/*
 * _set_memory_prot is an internal helper for callers that have been passed
 * a pgprot_t value from upper layers and a reservation has already been taken.
 * If you want to set the pgprot to a specific page protocol, use the
 * set_memory_xx() functions.
 */
int __set_memory_prot(unsigned long addr, int numpages, pgprot_t prot)
{
        return change_page_attr_set_clr(&addr, numpages, prot,
                                        __pgprot(~pgprot_val(prot)), 0, 0,
                                        NULL);
}

int _set_memory_uc(unsigned long addr, int numpages)
{
        /*
         * for now UC MINUS. see comments in ioremap()
         * If you really need strong UC use ioremap_uc(), but note
         * that you cannot override IO areas with set_memory_*() as
         * these helpers cannot work with IO memory.
         */
        return change_page_attr_set(&addr, numpages,
                                    cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS),
                                    0);
}

int set_memory_uc(unsigned long addr, int numpages)
{
        int ret;

        /*
         * for now UC MINUS. see comments in ioremap()
         */
        ret = memtype_reserve(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
                              _PAGE_CACHE_MODE_UC_MINUS, NULL);
        if (ret)
                goto out_err;

        ret = _set_memory_uc(addr, numpages);
        if (ret)
                goto out_free;

        return 0;

out_free:
        memtype_free(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
out_err:
        return ret;
}
EXPORT_SYMBOL(set_memory_uc);

int _set_memory_wc(unsigned long addr, int numpages)
{
        int ret;

        ret = change_page_attr_set(&addr, numpages,
                                   cachemode2pgprot(_PAGE_CACHE_MODE_UC_MINUS),
                                   0);
        if (!ret) {
                ret = change_page_attr_set_clr(&addr, numpages,
                                               cachemode2pgprot(_PAGE_CACHE_MODE_WC),
                                               __pgprot(_PAGE_CACHE_MASK),
                                               0, 0, NULL);
        }
        return ret;
}

int set_memory_wc(unsigned long addr, int numpages)
{
        int ret;

        ret = memtype_reserve(__pa(addr), __pa(addr) + numpages * PAGE_SIZE,
                _PAGE_CACHE_MODE_WC, NULL);
        if (ret)
                return ret;

        ret = _set_memory_wc(addr, numpages);
        if (ret)
                memtype_free(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);

        return ret;
}
EXPORT_SYMBOL(set_memory_wc);

int _set_memory_wt(unsigned long addr, int numpages)
{
        return change_page_attr_set(&addr, numpages,
                                    cachemode2pgprot(_PAGE_CACHE_MODE_WT), 0);
}

int _set_memory_wb(unsigned long addr, int numpages)
{
        /* WB cache mode is hard wired to all cache attribute bits being 0 */
        return change_page_attr_clear(&addr, numpages,
                                      __pgprot(_PAGE_CACHE_MASK), 0);
}

int set_memory_wb(unsigned long addr, int numpages)
{
        int ret;

        ret = _set_memory_wb(addr, numpages);
        if (ret)
                return ret;

        memtype_free(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
        return 0;
}
EXPORT_SYMBOL(set_memory_wb);

int set_memory_x(unsigned long addr, int numpages)
{
        if (!(__supported_pte_mask & _PAGE_NX))
                return 0;

        return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_NX), 0);
}

int set_memory_nx(unsigned long addr, int numpages)
{
        if (!(__supported_pte_mask & _PAGE_NX))
                return 0;

        return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_NX), 0);
}

int set_memory_ro(unsigned long addr, int numpages)
{
        return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_RW), 0);
}

int set_memory_rw(unsigned long addr, int numpages)
{
        return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_RW), 0);
}

int set_memory_np(unsigned long addr, int numpages)
{
        return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_PRESENT), 0);
}

int set_memory_np_noalias(unsigned long addr, int numpages)
{
        int cpa_flags = CPA_NO_CHECK_ALIAS;

        return change_page_attr_set_clr(&addr, numpages, __pgprot(0),
                                        __pgprot(_PAGE_PRESENT), 0,
                                        cpa_flags, NULL);
}

int set_memory_4k(unsigned long addr, int numpages)
{
        return change_page_attr_set_clr(&addr, numpages, __pgprot(0),
                                        __pgprot(0), 1, 0, NULL);
}

int set_memory_nonglobal(unsigned long addr, int numpages)
{
        return change_page_attr_clear(&addr, numpages,
                                      __pgprot(_PAGE_GLOBAL), 0);
}

int set_memory_global(unsigned long addr, int numpages)
{
        return change_page_attr_set(&addr, numpages,
                                    __pgprot(_PAGE_GLOBAL), 0);
}

static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
{
        struct cpa_data cpa;
        int ret;

        /* Nothing to do if memory encryption is not active */
        if (!mem_encrypt_active())
                return 0;

        /* Should not be working on unaligned addresses */
        if (WARN_ONCE(addr & ~PAGE_MASK, "misaligned address: %#lx\n", addr))
                addr &= PAGE_MASK;

        memset(&cpa, 0, sizeof(cpa));
        cpa.vaddr = &addr;
        cpa.numpages = numpages;
        cpa.mask_set = enc ? __pgprot(_PAGE_ENC) : __pgprot(0);
        cpa.mask_clr = enc ? __pgprot(0) : __pgprot(_PAGE_ENC);

        cpa.pgd = init_mm.pgd;

        /* Must avoid aliasing mappings in the highmem code */
        kmap_flush_unused();
        vm_unmap_aliases();

        /*
         * Before changing the encryption attribute, we need to flush caches.
         */
        cpa_flush(&cpa, !this_cpu_has(X86_FEATURE_SME_COHERENT));

        ret = __change_page_attr_set_clr(&cpa, 1);

        /*
         * After changing the encryption attribute, we need to flush TLBs again
         * in case any speculative TLB caching occurred (but no need to flush
         * caches again).  We could just use cpa_flush_all(), but in case TLB
         * flushing gets optimized in the cpa_flush() path use the same logic
         * as above.
         */
        cpa_flush(&cpa, 0);

        return ret;
}

int set_memory_encrypted(unsigned long addr, int numpages)
{
        return __set_memory_enc_dec(addr, numpages, true);
}
EXPORT_SYMBOL_GPL(set_memory_encrypted);

int set_memory_decrypted(unsigned long addr, int numpages)
{
        return __set_memory_enc_dec(addr, numpages, false);
}
EXPORT_SYMBOL_GPL(set_memory_decrypted);

int set_pages_uc(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_uc(addr, numpages);
}
EXPORT_SYMBOL(set_pages_uc);

static int _set_pages_array(struct page **pages, int numpages,
                enum page_cache_mode new_type)
{
        unsigned long start;
        unsigned long end;
        enum page_cache_mode set_type;
        int i;
        int free_idx;
        int ret;

        for (i = 0; i < numpages; i++) {
                if (PageHighMem(pages[i]))
                        continue;
                start = page_to_pfn(pages[i]) << PAGE_SHIFT;
                end = start + PAGE_SIZE;
                if (memtype_reserve(start, end, new_type, NULL))
                        goto err_out;
        }

        /* If WC, set to UC- first and then WC */
        set_type = (new_type == _PAGE_CACHE_MODE_WC) ?
                                _PAGE_CACHE_MODE_UC_MINUS : new_type;

        ret = cpa_set_pages_array(pages, numpages,
                                  cachemode2pgprot(set_type));
        if (!ret && new_type == _PAGE_CACHE_MODE_WC)
                ret = change_page_attr_set_clr(NULL, numpages,
                                               cachemode2pgprot(
                                                _PAGE_CACHE_MODE_WC),
                                               __pgprot(_PAGE_CACHE_MASK),
                                               0, CPA_PAGES_ARRAY, pages);
        if (ret)
                goto err_out;
        return 0; /* Success */
err_out:
        free_idx = i;
        for (i = 0; i < free_idx; i++) {
                if (PageHighMem(pages[i]))
                        continue;
                start = page_to_pfn(pages[i]) << PAGE_SHIFT;
                end = start + PAGE_SIZE;
                memtype_free(start, end);
        }
        return -EINVAL;
}

int set_pages_array_uc(struct page **pages, int numpages)
{
        return _set_pages_array(pages, numpages, _PAGE_CACHE_MODE_UC_MINUS);
}
EXPORT_SYMBOL(set_pages_array_uc);

int set_pages_array_wc(struct page **pages, int numpages)
{
        return _set_pages_array(pages, numpages, _PAGE_CACHE_MODE_WC);
}
EXPORT_SYMBOL(set_pages_array_wc);

int set_pages_array_wt(struct page **pages, int numpages)
{
        return _set_pages_array(pages, numpages, _PAGE_CACHE_MODE_WT);
}
EXPORT_SYMBOL_GPL(set_pages_array_wt);

int set_pages_wb(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_wb(addr, numpages);
}
EXPORT_SYMBOL(set_pages_wb);

int set_pages_array_wb(struct page **pages, int numpages)
{
        int retval;
        unsigned long start;
        unsigned long end;
        int i;

        /* WB cache mode is hard wired to all cache attribute bits being 0 */
        retval = cpa_clear_pages_array(pages, numpages,
                        __pgprot(_PAGE_CACHE_MASK));
        if (retval)
                return retval;

        for (i = 0; i < numpages; i++) {
                if (PageHighMem(pages[i]))
                        continue;
                start = page_to_pfn(pages[i]) << PAGE_SHIFT;
                end = start + PAGE_SIZE;
                memtype_free(start, end);
        }

        return 0;
}
EXPORT_SYMBOL(set_pages_array_wb);

int set_pages_ro(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_ro(addr, numpages);
}

int set_pages_rw(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_rw(addr, numpages);
}

static int __set_pages_p(struct page *page, int numpages)
{
        unsigned long tempaddr = (unsigned long) page_address(page);
        struct cpa_data cpa = { .vaddr = &tempaddr,
                                .pgd = NULL,
                                .numpages = numpages,
                                .mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
                                .mask_clr = __pgprot(0),
                                .flags = 0};

        /*
         * No alias checking needed for setting present flag. otherwise,
         * we may need to break large pages for 64-bit kernel text
         * mappings (this adds to complexity if we want to do this from
         * atomic context especially). Let's keep it simple!
         */
        return __change_page_attr_set_clr(&cpa, 0);
}

static int __set_pages_np(struct page *page, int numpages)
{
        unsigned long tempaddr = (unsigned long) page_address(page);
        struct cpa_data cpa = { .vaddr = &tempaddr,
                                .pgd = NULL,
                                .numpages = numpages,
                                .mask_set = __pgprot(0),
                                .mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW),
                                .flags = 0};

        /*
         * No alias checking needed for setting not present flag. otherwise,
         * we may need to break large pages for 64-bit kernel text
         * mappings (this adds to complexity if we want to do this from
         * atomic context especially). Let's keep it simple!
         */
        return __change_page_attr_set_clr(&cpa, 0);
}

int set_direct_map_invalid_noflush(struct page *page)
{
        return __set_pages_np(page, 1);
}

int set_direct_map_default_noflush(struct page *page)
{
        return __set_pages_p(page, 1);
}

#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
        if (PageHighMem(page))
                return;
        if (!enable) {
                debug_check_no_locks_freed(page_address(page),
                                           numpages * PAGE_SIZE);
        }

        /*
         * The return value is ignored as the calls cannot fail.
         * Large pages for identity mappings are not used at boot time
         * and hence no memory allocations during large page split.
         */
        if (enable)
                __set_pages_p(page, numpages);
        else
                __set_pages_np(page, numpages);

        /*
         * We should perform an IPI and flush all tlbs,
         * but that can deadlock->flush only current cpu.
         * Preemption needs to be disabled around __flush_tlb_all() due to
         * CR3 reload in __native_flush_tlb().
         */
        preempt_disable();
        __flush_tlb_all();
        preempt_enable();

        arch_flush_lazy_mmu_mode();
}
#endif /* CONFIG_DEBUG_PAGEALLOC */

bool kernel_page_present(struct page *page)
{
        unsigned int level;
        pte_t *pte;

        if (PageHighMem(page))
                return false;

        pte = lookup_address((unsigned long)page_address(page), &level);
        return (pte_val(*pte) & _PAGE_PRESENT);
}

int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
                                   unsigned numpages, unsigned long page_flags)
{
        int retval = -EINVAL;

        struct cpa_data cpa = {
                .vaddr = &address,
                .pfn = pfn,
                .pgd = pgd,
                .numpages = numpages,
                .mask_set = __pgprot(0),
                .mask_clr = __pgprot(~page_flags & (_PAGE_NX|_PAGE_RW)),
                .flags = 0,
        };

        WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");

        if (!(__supported_pte_mask & _PAGE_NX))
                goto out;

        if (!(page_flags & _PAGE_ENC))
                cpa.mask_clr = pgprot_encrypted(cpa.mask_clr);

        cpa.mask_set = __pgprot(_PAGE_PRESENT | page_flags);

        retval = __change_page_attr_set_clr(&cpa, 0);
        __flush_tlb_all();

out:
        return retval;
}

/*
 * __flush_tlb_all() flushes mappings only on current CPU and hence this
 * function shouldn't be used in an SMP environment. Presently, it's used only
 * during boot (way before smp_init()) by EFI subsystem and hence is ok.
 */
int __init kernel_unmap_pages_in_pgd(pgd_t *pgd, unsigned long address,
                                     unsigned long numpages)
{
        int retval;

        /*
         * The typical sequence for unmapping is to find a pte through
         * lookup_address_in_pgd() (ideally, it should never return NULL because
         * the address is already mapped) and change it's protections. As pfn is
         * the *target* of a mapping, it's not useful while unmapping.
         */
        struct cpa_data cpa = {
                .vaddr          = &address,
                .pfn            = 0,
                .pgd            = pgd,
                .numpages       = numpages,
                .mask_set       = __pgprot(0),
                .mask_clr       = __pgprot(_PAGE_PRESENT | _PAGE_RW),
                .flags          = 0,
        };

        WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");

        retval = __change_page_attr_set_clr(&cpa, 0);
        __flush_tlb_all();

        return retval;
}

/*
 * The testcases use internal knowledge of the implementation that shouldn't
 * be exposed to the rest of the kernel. Include these directly here.
 */
#ifdef CONFIG_CPA_DEBUG
#include "cpa-test.c"
#endif