x86/xen/mmu_hvm.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/types.h>
0003 #include <linux/crash_dump.h>
0004
0005 #include <xen/interface/xen.h>
0006 #include <xen/hvm.h>
0007
0008 #include "mmu.h"
0009
0010 #ifdef CONFIG_PROC_VMCORE
0011 /*
0012  * The kdump kernel has to check whether a pfn of the crashed kernel
0013  * was a ballooned page. vmcore is using this function to decide
0014  * whether to access a pfn of the crashed kernel.
0015  * Returns "false" if the pfn is not backed by a RAM page, the caller may
0016  * handle the pfn special in this case.
0017  */
0018 static bool xen_vmcore_pfn_is_ram(struct vmcore_cb *cb, unsigned long pfn)
0019 {
0020     struct xen_hvm_get_mem_type a = {
0021         .domid = DOMID_SELF,
0022         .pfn = pfn,
0023     };
0024
0025     if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) {
0026         pr_warn_once("Unexpected HVMOP_get_mem_type failure\n");
0027         return true;
0028     }
0029     return a.mem_type != HVMMEM_mmio_dm;
0030 }
0031 static struct vmcore_cb xen_vmcore_cb = {
0032     .pfn_is_ram = xen_vmcore_pfn_is_ram,
0033 };
0034 #endif
0035
0036 static void xen_hvm_exit_mmap(struct mm_struct *mm)
0037 {
0038     struct xen_hvm_pagetable_dying a;
0039     int rc;
0040
0041     a.domid = DOMID_SELF;
0042     a.gpa = __pa(mm->pgd);
0043     rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
0044     WARN_ON_ONCE(rc < 0);
0045 }
0046
0047 static int is_pagetable_dying_supported(void)
0048 {
0049     struct xen_hvm_pagetable_dying a;
0050     int rc = 0;
0051
0052     a.domid = DOMID_SELF;
0053     a.gpa = 0x00;
0054     rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
0055     if (rc < 0) {
0056         printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
0057         return 0;
0058     }
0059     return 1;
0060 }
0061
0062 void __init xen_hvm_init_mmu_ops(void)
0063 {
0064     if (is_pagetable_dying_supported())
0065         pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
0066 #ifdef CONFIG_PROC_VMCORE
0067     register_vmcore_cb(&xen_vmcore_cb);
0068 #endif
0069 }