arch/x86/xen/mmu_hvm.c

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