arch/x86/xen/mmu_hvm.c

   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  * The kdump kernel has to check whether a pfn of the crashed kernel
  13  * was a ballooned page. vmcore is using this function to decide
  14  * whether to access a pfn of the crashed kernel.
  15  * Returns 0 if the pfn is not backed by a RAM page, the caller may
  16  * handle the pfn special in this case.
  17  */
  18 static int xen_oldmem_pfn_is_ram(unsigned long pfn)
  19 {
  20         struct xen_hvm_get_mem_type a = {
  21                 .domid = DOMID_SELF,
  22                 .pfn = pfn,
  23         };
  24
  25         if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) {
  26                 pr_warn_once("Unexpected HVMOP_get_mem_type failure\n");
  27                 return -ENXIO;
  28         }
  29         return a.mem_type != HVMMEM_mmio_dm;
  30 }
  31 #endif
  32
  33 static void xen_hvm_exit_mmap(struct mm_struct *mm)
  34 {
  35         struct xen_hvm_pagetable_dying a;
  36         int rc;
  37
  38         a.domid = DOMID_SELF;
  39         a.gpa = __pa(mm->pgd);
  40         rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  41         WARN_ON_ONCE(rc < 0);
  42 }
  43
  44 static int is_pagetable_dying_supported(void)
  45 {
  46         struct xen_hvm_pagetable_dying a;
  47         int rc = 0;
  48
  49         a.domid = DOMID_SELF;
  50         a.gpa = 0x00;
  51         rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  52         if (rc < 0) {
  53                 printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
  54                 return 0;
  55         }
  56         return 1;
  57 }
  58
  59 void __init xen_hvm_init_mmu_ops(void)
  60 {
  61         if (is_pagetable_dying_supported())
  62                 pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
  63 #ifdef CONFIG_PROC_VMCORE
  64         WARN_ON(register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram));
  65 #endif
  66 }