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 "false" if the pfn is not backed by a RAM page, the caller may
16  * handle the pfn special in this case.
17  */
xen_vmcore_pfn_is_ram(struct vmcore_cb * cb,unsigned long pfn)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 
xen_hvm_exit_mmap(struct mm_struct * mm)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 
is_pagetable_dying_supported(void)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 
xen_hvm_init_mmu_ops(void)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 }
70