/*
 * vMTRR implementation
 *
 * Copyright (C) 2006 Qumranet, Inc.
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 * Copyright(C) 2015 Intel Corporation.
 *
 * Authors:
 *   Yaniv Kamay  <yaniv@qumranet.com>
 *   Avi Kivity   <avi@qumranet.com>
 *   Marcelo Tosatti <mtosatti@redhat.com>
 *   Paolo Bonzini <pbonzini@redhat.com>
 *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 */

#include <linux/kvm_host.h>
#include <asm/mtrr.h>

#include "cpuid.h"
#include "mmu.h"

#define IA32_MTRR_DEF_TYPE_E            (1ULL << 11)
#define IA32_MTRR_DEF_TYPE_FE           (1ULL << 10)
#define IA32_MTRR_DEF_TYPE_TYPE_MASK    (0xff)

static bool msr_mtrr_valid(unsigned msr)
{
        switch (msr) {
        case 0x200 ... 0x200 + 2 * KVM_NR_VAR_MTRR - 1:
        case MSR_MTRRfix64K_00000:
        case MSR_MTRRfix16K_80000:
        case MSR_MTRRfix16K_A0000:
        case MSR_MTRRfix4K_C0000:
        case MSR_MTRRfix4K_C8000:
        case MSR_MTRRfix4K_D0000:
        case MSR_MTRRfix4K_D8000:
        case MSR_MTRRfix4K_E0000:
        case MSR_MTRRfix4K_E8000:
        case MSR_MTRRfix4K_F0000:
        case MSR_MTRRfix4K_F8000:
        case MSR_MTRRdefType:
        case MSR_IA32_CR_PAT:
                return true;
        }
        return false;
}

static bool valid_pat_type(unsigned t)
{
        return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
}

static bool valid_mtrr_type(unsigned t)
{
        return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
}

bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
        int i;
        u64 mask;

        if (!msr_mtrr_valid(msr))
                return false;

        if (msr == MSR_IA32_CR_PAT) {
                for (i = 0; i < 8; i++)
                        if (!valid_pat_type((data >> (i * 8)) & 0xff))
                                return false;
                return true;
        } else if (msr == MSR_MTRRdefType) {
                if (data & ~0xcff)
                        return false;
                return valid_mtrr_type(data & 0xff);
        } else if (msr >= MSR_MTRRfix64K_00000 && msr <= MSR_MTRRfix4K_F8000) {
                for (i = 0; i < 8 ; i++)
                        if (!valid_mtrr_type((data >> (i * 8)) & 0xff))
                                return false;
                return true;
        }

        /* variable MTRRs */
        WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR));

        mask = (~0ULL) << cpuid_maxphyaddr(vcpu);
        if ((msr & 1) == 0) {
                /* MTRR base */
                if (!valid_mtrr_type(data & 0xff))
                        return false;
                mask |= 0xf00;
        } else
                /* MTRR mask */
                mask |= 0x7ff;
        if (data & mask) {
                kvm_inject_gp(vcpu, 0);
                return false;
        }

        return true;
}
EXPORT_SYMBOL_GPL(kvm_mtrr_valid);

static bool mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
{
        return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_E);
}

static bool fixed_mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
{
        return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_FE);
}

static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state)
{
        return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK;
}

static u8 mtrr_disabled_type(struct kvm_vcpu *vcpu)
{
        /*
         * Intel SDM 11.11.2.2: all MTRRs are disabled when
         * IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC
         * memory type is applied to all of physical memory.
         *
         * However, virtual machines can be run with CPUID such that
         * there are no MTRRs.  In that case, the firmware will never
         * enable MTRRs and it is obviously undesirable to run the
         * guest entirely with UC memory and we use WB.
         */
        if (guest_cpuid_has(vcpu, X86_FEATURE_MTRR))
                return MTRR_TYPE_UNCACHABLE;
        else
                return MTRR_TYPE_WRBACK;
}

/*
* Three terms are used in the following code:
* - segment, it indicates the address segments covered by fixed MTRRs.
* - unit, it corresponds to the MSR entry in the segment.
* - range, a range is covered in one memory cache type.
*/
struct fixed_mtrr_segment {
        u64 start;
        u64 end;

        int range_shift;

        /* the start position in kvm_mtrr.fixed_ranges[]. */
        int range_start;
};

static struct fixed_mtrr_segment fixed_seg_table[] = {
        /* MSR_MTRRfix64K_00000, 1 unit. 64K fixed mtrr. */
        {
                .start = 0x0,
                .end = 0x80000,
                .range_shift = 16, /* 64K */
                .range_start = 0,
        },

        /*
         * MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000, 2 units,
         * 16K fixed mtrr.
         */
        {
                .start = 0x80000,
                .end = 0xc0000,
                .range_shift = 14, /* 16K */
                .range_start = 8,
        },

        /*
         * MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000, 8 units,
         * 4K fixed mtrr.
         */
        {
                .start = 0xc0000,
                .end = 0x100000,
                .range_shift = 12, /* 12K */
                .range_start = 24,
        }
};

/*
 * The size of unit is covered in one MSR, one MSR entry contains
 * 8 ranges so that unit size is always 8 * 2^range_shift.
 */
static u64 fixed_mtrr_seg_unit_size(int seg)
{
        return 8 << fixed_seg_table[seg].range_shift;
}

static bool fixed_msr_to_seg_unit(u32 msr, int *seg, int *unit)
{
        switch (msr) {
        case MSR_MTRRfix64K_00000:
                *seg = 0;
                *unit = 0;
                break;
        case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000:
                *seg = 1;
                *unit = msr - MSR_MTRRfix16K_80000;
                break;
        case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
                *seg = 2;
                *unit = msr - MSR_MTRRfix4K_C0000;
                break;
        default:
                return false;
        }

        return true;
}

static void fixed_mtrr_seg_unit_range(int seg, int unit, u64 *start, u64 *end)
{
        struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
        u64 unit_size = fixed_mtrr_seg_unit_size(seg);

        *start = mtrr_seg->start + unit * unit_size;
        *end = *start + unit_size;
        WARN_ON(*end > mtrr_seg->end);
}

static int fixed_mtrr_seg_unit_range_index(int seg, int unit)
{
        struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];

        WARN_ON(mtrr_seg->start + unit * fixed_mtrr_seg_unit_size(seg)
                > mtrr_seg->end);

        /* each unit has 8 ranges. */
        return mtrr_seg->range_start + 8 * unit;
}

static int fixed_mtrr_seg_end_range_index(int seg)
{
        struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
        int n;

        n = (mtrr_seg->end - mtrr_seg->start) >> mtrr_seg->range_shift;
        return mtrr_seg->range_start + n - 1;
}

static bool fixed_msr_to_range(u32 msr, u64 *start, u64 *end)
{
        int seg, unit;

        if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
                return false;

        fixed_mtrr_seg_unit_range(seg, unit, start, end);
        return true;
}

static int fixed_msr_to_range_index(u32 msr)
{
        int seg, unit;

        if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
                return -1;

        return fixed_mtrr_seg_unit_range_index(seg, unit);
}

static int fixed_mtrr_addr_to_seg(u64 addr)
{
        struct fixed_mtrr_segment *mtrr_seg;
        int seg, seg_num = ARRAY_SIZE(fixed_seg_table);

        for (seg = 0; seg < seg_num; seg++) {
                mtrr_seg = &fixed_seg_table[seg];
                if (mtrr_seg->start <= addr && addr < mtrr_seg->end)
                        return seg;
        }

        return -1;
}

static int fixed_mtrr_addr_seg_to_range_index(u64 addr, int seg)
{
        struct fixed_mtrr_segment *mtrr_seg;
        int index;

        mtrr_seg = &fixed_seg_table[seg];
        index = mtrr_seg->range_start;
        index += (addr - mtrr_seg->start) >> mtrr_seg->range_shift;
        return index;
}

static u64 fixed_mtrr_range_end_addr(int seg, int index)
{
        struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
        int pos = index - mtrr_seg->range_start;

        return mtrr_seg->start + ((pos + 1) << mtrr_seg->range_shift);
}

static void var_mtrr_range(struct kvm_mtrr_range *range, u64 *start, u64 *end)
{
        u64 mask;

        *start = range->base & PAGE_MASK;

        mask = range->mask & PAGE_MASK;

        /* This cannot overflow because writing to the reserved bits of
         * variable MTRRs causes a #GP.
         */
        *end = (*start | ~mask) + 1;
}

static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
{
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
        gfn_t start, end;
        int index;

        if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
              !kvm_arch_has_noncoherent_dma(vcpu->kvm))
                return;

        if (!mtrr_is_enabled(mtrr_state) && msr != MSR_MTRRdefType)
                return;

        /* fixed MTRRs. */
        if (fixed_msr_to_range(msr, &start, &end)) {
                if (!fixed_mtrr_is_enabled(mtrr_state))
                        return;
        } else if (msr == MSR_MTRRdefType) {
                start = 0x0;
                end = ~0ULL;
        } else {
                /* variable range MTRRs. */
                index = (msr - 0x200) / 2;
                var_mtrr_range(&mtrr_state->var_ranges[index], &start, &end);
        }

        kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
}

static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range)
{
        return (range->mask & (1 << 11)) != 0;
}

static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
        struct kvm_mtrr_range *tmp, *cur;
        int index, is_mtrr_mask;

        index = (msr - 0x200) / 2;
        is_mtrr_mask = msr - 0x200 - 2 * index;
        cur = &mtrr_state->var_ranges[index];

        /* remove the entry if it's in the list. */
        if (var_mtrr_range_is_valid(cur))
                list_del(&mtrr_state->var_ranges[index].node);

        /* Extend the mask with all 1 bits to the left, since those
         * bits must implicitly be 0.  The bits are then cleared
         * when reading them.
         */
        if (!is_mtrr_mask)
                cur->base = data;
        else
                cur->mask = data | (-1LL << cpuid_maxphyaddr(vcpu));

        /* add it to the list if it's enabled. */
        if (var_mtrr_range_is_valid(cur)) {
                list_for_each_entry(tmp, &mtrr_state->head, node)
                        if (cur->base >= tmp->base)
                                break;
                list_add_tail(&cur->node, &tmp->node);
        }
}

int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
        int index;

        if (!kvm_mtrr_valid(vcpu, msr, data))
                return 1;

        index = fixed_msr_to_range_index(msr);
        if (index >= 0)
                *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index] = data;
        else if (msr == MSR_MTRRdefType)
                vcpu->arch.mtrr_state.deftype = data;
        else if (msr == MSR_IA32_CR_PAT)
                vcpu->arch.pat = data;
        else
                set_var_mtrr_msr(vcpu, msr, data);

        update_mtrr(vcpu, msr);
        return 0;
}

int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
{
        int index;

        /* MSR_MTRRcap is a readonly MSR. */
        if (msr == MSR_MTRRcap) {
                /*
                 * SMRR = 0
                 * WC = 1
                 * FIX = 1
                 * VCNT = KVM_NR_VAR_MTRR
                 */
                *pdata = 0x500 | KVM_NR_VAR_MTRR;
                return 0;
        }

        if (!msr_mtrr_valid(msr))
                return 1;

        index = fixed_msr_to_range_index(msr);
        if (index >= 0)
                *pdata = *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index];
        else if (msr == MSR_MTRRdefType)
                *pdata = vcpu->arch.mtrr_state.deftype;
        else if (msr == MSR_IA32_CR_PAT)
                *pdata = vcpu->arch.pat;
        else {  /* Variable MTRRs */
                int is_mtrr_mask;

                index = (msr - 0x200) / 2;
                is_mtrr_mask = msr - 0x200 - 2 * index;
                if (!is_mtrr_mask)
                        *pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
                else
                        *pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;

                *pdata &= (1ULL << cpuid_maxphyaddr(vcpu)) - 1;
        }

        return 0;
}

void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
{
        INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
}

struct mtrr_iter {
        /* input fields. */
        struct kvm_mtrr *mtrr_state;
        u64 start;
        u64 end;

        /* output fields. */
        int mem_type;
        /* mtrr is completely disabled? */
        bool mtrr_disabled;
        /* [start, end) is not fully covered in MTRRs? */
        bool partial_map;

        /* private fields. */
        union {
                /* used for fixed MTRRs. */
                struct {
                        int index;
                        int seg;
                };

                /* used for var MTRRs. */
                struct {
                        struct kvm_mtrr_range *range;
                        /* max address has been covered in var MTRRs. */
                        u64 start_max;
                };
        };

        bool fixed;
};

static bool mtrr_lookup_fixed_start(struct mtrr_iter *iter)
{
        int seg, index;

        if (!fixed_mtrr_is_enabled(iter->mtrr_state))
                return false;

        seg = fixed_mtrr_addr_to_seg(iter->start);
        if (seg < 0)
                return false;

        iter->fixed = true;
        index = fixed_mtrr_addr_seg_to_range_index(iter->start, seg);
        iter->index = index;
        iter->seg = seg;
        return true;
}

static bool match_var_range(struct mtrr_iter *iter,
                            struct kvm_mtrr_range *range)
{
        u64 start, end;

        var_mtrr_range(range, &start, &end);
        if (!(start >= iter->end || end <= iter->start)) {
                iter->range = range;

                /*
                 * the function is called when we do kvm_mtrr.head walking.
                 * Range has the minimum base address which interleaves
                 * [looker->start_max, looker->end).
                 */
                iter->partial_map |= iter->start_max < start;

                /* update the max address has been covered. */
                iter->start_max = max(iter->start_max, end);
                return true;
        }

        return false;
}

static void __mtrr_lookup_var_next(struct mtrr_iter *iter)
{
        struct kvm_mtrr *mtrr_state = iter->mtrr_state;

        list_for_each_entry_continue(iter->range, &mtrr_state->head, node)
                if (match_var_range(iter, iter->range))
                        return;

        iter->range = NULL;
        iter->partial_map |= iter->start_max < iter->end;
}

static void mtrr_lookup_var_start(struct mtrr_iter *iter)
{
        struct kvm_mtrr *mtrr_state = iter->mtrr_state;

        iter->fixed = false;
        iter->start_max = iter->start;
        iter->range = NULL;
        iter->range = list_prepare_entry(iter->range, &mtrr_state->head, node);

        __mtrr_lookup_var_next(iter);
}

static void mtrr_lookup_fixed_next(struct mtrr_iter *iter)
{
        /* terminate the lookup. */
        if (fixed_mtrr_range_end_addr(iter->seg, iter->index) >= iter->end) {
                iter->fixed = false;
                iter->range = NULL;
                return;
        }

        iter->index++;

        /* have looked up for all fixed MTRRs. */
        if (iter->index >= ARRAY_SIZE(iter->mtrr_state->fixed_ranges))
                return mtrr_lookup_var_start(iter);

        /* switch to next segment. */
        if (iter->index > fixed_mtrr_seg_end_range_index(iter->seg))
                iter->seg++;
}

static void mtrr_lookup_var_next(struct mtrr_iter *iter)
{
        __mtrr_lookup_var_next(iter);
}

static void mtrr_lookup_start(struct mtrr_iter *iter)
{
        if (!mtrr_is_enabled(iter->mtrr_state)) {
                iter->mtrr_disabled = true;
                return;
        }

        if (!mtrr_lookup_fixed_start(iter))
                mtrr_lookup_var_start(iter);
}

static void mtrr_lookup_init(struct mtrr_iter *iter,
                             struct kvm_mtrr *mtrr_state, u64 start, u64 end)
{
        iter->mtrr_state = mtrr_state;
        iter->start = start;
        iter->end = end;
        iter->mtrr_disabled = false;
        iter->partial_map = false;
        iter->fixed = false;
        iter->range = NULL;

        mtrr_lookup_start(iter);
}

static bool mtrr_lookup_okay(struct mtrr_iter *iter)
{
        if (iter->fixed) {
                iter->mem_type = iter->mtrr_state->fixed_ranges[iter->index];
                return true;
        }

        if (iter->range) {
                iter->mem_type = iter->range->base & 0xff;
                return true;
        }

        return false;
}

static void mtrr_lookup_next(struct mtrr_iter *iter)
{
        if (iter->fixed)
                mtrr_lookup_fixed_next(iter);
        else
                mtrr_lookup_var_next(iter);
}

#define mtrr_for_each_mem_type(_iter_, _mtrr_, _gpa_start_, _gpa_end_) \
        for (mtrr_lookup_init(_iter_, _mtrr_, _gpa_start_, _gpa_end_); \
             mtrr_lookup_okay(_iter_); mtrr_lookup_next(_iter_))

u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
{
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
        struct mtrr_iter iter;
        u64 start, end;
        int type = -1;
        const int wt_wb_mask = (1 << MTRR_TYPE_WRBACK)
                               | (1 << MTRR_TYPE_WRTHROUGH);

        start = gfn_to_gpa(gfn);
        end = start + PAGE_SIZE;

        mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
                int curr_type = iter.mem_type;

                /*
                 * Please refer to Intel SDM Volume 3: 11.11.4.1 MTRR
                 * Precedences.
                 */

                if (type == -1) {
                        type = curr_type;
                        continue;
                }

                /*
                 * If two or more variable memory ranges match and the
                 * memory types are identical, then that memory type is
                 * used.
                 */
                if (type == curr_type)
                        continue;

                /*
                 * If two or more variable memory ranges match and one of
                 * the memory types is UC, the UC memory type used.
                 */
                if (curr_type == MTRR_TYPE_UNCACHABLE)
                        return MTRR_TYPE_UNCACHABLE;

                /*
                 * If two or more variable memory ranges match and the
                 * memory types are WT and WB, the WT memory type is used.
                 */
                if (((1 << type) & wt_wb_mask) &&
                      ((1 << curr_type) & wt_wb_mask)) {
                        type = MTRR_TYPE_WRTHROUGH;
                        continue;
                }

                /*
                 * For overlaps not defined by the above rules, processor
                 * behavior is undefined.
                 */

                /* We use WB for this undefined behavior. :( */
                return MTRR_TYPE_WRBACK;
        }

        if (iter.mtrr_disabled)
                return mtrr_disabled_type(vcpu);

        /* not contained in any MTRRs. */
        if (type == -1)
                return mtrr_default_type(mtrr_state);

        /*
         * We just check one page, partially covered by MTRRs is
         * impossible.
         */
        WARN_ON(iter.partial_map);

        return type;
}
EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);

bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
                                          int page_num)
{
        struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
        struct mtrr_iter iter;
        u64 start, end;
        int type = -1;

        start = gfn_to_gpa(gfn);
        end = gfn_to_gpa(gfn + page_num);
        mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
                if (type == -1) {
                        type = iter.mem_type;
                        continue;
                }

                if (type != iter.mem_type)
                        return false;
        }

        if (iter.mtrr_disabled)
                return true;

        if (!iter.partial_map)
                return true;

        if (type == -1)
                return true;

        return type == mtrr_default_type(mtrr_state);
}