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 "xen-ops.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 "false" if the pfn is not backed by a RAM page, the caller may
  16  * handle the pfn special in this case.
  17  */
  18 static bool xen_vmcore_pfn_is_ram(struct vmcore_cb *cb, 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 true;
  28         }
  29         return a.mem_type != HVMMEM_mmio_dm;
  30 }
  31 static struct vmcore_cb xen_vmcore_cb = {
  32         .pfn_is_ram = xen_vmcore_pfn_is_ram,
  33 };
  34 #endif
  35
  36 static void xen_hvm_exit_mmap(struct mm_struct *mm)
  37 {
  38         struct xen_hvm_pagetable_dying a;
  39         int rc;
  40
  41         a.domid = DOMID_SELF;
  42         a.gpa = __pa(mm->pgd);
  43         rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  44         WARN_ON_ONCE(rc < 0);
  45 }
  46
  47 static int is_pagetable_dying_supported(void)
  48 {
  49         struct xen_hvm_pagetable_dying a;
  50         int rc = 0;
  51
  52         a.domid = DOMID_SELF;
  53         a.gpa = 0x00;
  54         rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
  55         if (rc < 0) {
  56                 printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
  57                 return 0;
  58         }
  59         return 1;
  60 }
  61
  62 void __init xen_hvm_init_mmu_ops(void)
  63 {
  64         if (is_pagetable_dying_supported())
  65                 pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
  66 #ifdef CONFIG_PROC_VMCORE
  67         register_vmcore_cb(&xen_vmcore_cb);
  68 #endif
  69 }