LXR linux/arch/x86/xen/mmu

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/types.h>
   3#include <linux/crash_dump.h>
   4
   5#include <xen/interface/xen.h>
   6#include <xen/hvm.h>
   7
   8#include "mmu.h"
   9
  10#ifdef CONFIG_PROC_VMCORE
  11/*
  12 * This function is used in two contexts:
  13 * - the kdump kernel has to check whether a pfn of the crashed kernel
  14 *   was a ballooned page. vmcore is using this function to decide
  15 *   whether to access a pfn of the crashed kernel.
  16 * - the kexec kernel has to check whether a pfn was ballooned by the
  17 *   previous kernel. If the pfn is ballooned, handle it properly.
  18 * Returns 0 if the pfn is not backed by a RAM page, the caller may
  19 * handle the pfn special in this case.
  20 */
  21static int xen_oldmem_pfn_is_ram(unsigned long pfn)
  22{
  23        struct xen_hvm_get_mem_type a = {
  24                .domid = DOMID_SELF,
  25                .pfn = pfn,
  26        };
  27        int ram;
  28
  29        if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
  30                return -ENXIO;
  31
  32        switch (a.mem_type) {
  33        case HVMMEM_mmio_dm:
  34                ram = 0;
  35                break;
  36        case HVMMEM_ram_rw:
  37        case HVMMEM_ram_ro:
  38        default:
  39                ram = 1;
  40                break;
  41        }
  42
  43        return ram;
  44}
  45#endif
  46
  47static void xen_hvm_exit_mmap(struct mm_struct *mm)
  48{
  49        struct xen_hvm_pagetable_dying a;
  50        int rc;
  51
  52        a.domid = DOMID_SELF;
  53        a.gpa = __pa(mm->pgd);
  54        rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  55        WARN_ON_ONCE(rc < 0);
  56}
  57
  58static int is_pagetable_dying_supported(void)
  59{
  60        struct xen_hvm_pagetable_dying a;
  61        int rc = 0;
  62
  63        a.domid = DOMID_SELF;
  64        a.gpa = 0x00;
  65        rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  66        if (rc < 0) {
  67                printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
  68                return 0;
  69        }
  70        return 1;
  71}
  72
  73void __init xen_hvm_init_mmu_ops(void)
  74{
  75        if (is_pagetable_dying_supported())
  76                pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
  77#ifdef CONFIG_PROC_VMCORE
  78        WARN_ON(register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram));
  79#endif
  80}
  81