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-rw-r--r--arch/x86/xen/mmu_hvm.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/arch/x86/xen/mmu_hvm.c b/arch/x86/xen/mmu_hvm.c
new file mode 100644
index 000000000000..1c57f1cd545c
--- /dev/null
+++ b/arch/x86/xen/mmu_hvm.c
@@ -0,0 +1,79 @@
+#include <linux/types.h>
+#include <linux/crash_dump.h>
+
+#include <xen/interface/xen.h>
+#include <xen/hvm.h>
+
+#include "mmu.h"
+
+#ifdef CONFIG_PROC_VMCORE
+/*
+ * This function is used in two contexts:
+ * - the kdump kernel has to check whether a pfn of the crashed kernel
+ * was a ballooned page. vmcore is using this function to decide
+ * whether to access a pfn of the crashed kernel.
+ * - the kexec kernel has to check whether a pfn was ballooned by the
+ * previous kernel. If the pfn is ballooned, handle it properly.
+ * Returns 0 if the pfn is not backed by a RAM page, the caller may
+ * handle the pfn special in this case.
+ */
+static int xen_oldmem_pfn_is_ram(unsigned long pfn)
+{
+ struct xen_hvm_get_mem_type a = {
+ .domid = DOMID_SELF,
+ .pfn = pfn,
+ };
+ int ram;
+
+ if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
+ return -ENXIO;
+
+ switch (a.mem_type) {
+ case HVMMEM_mmio_dm:
+ ram = 0;
+ break;
+ case HVMMEM_ram_rw:
+ case HVMMEM_ram_ro:
+ default:
+ ram = 1;
+ break;
+ }
+
+ return ram;
+}
+#endif
+
+static void xen_hvm_exit_mmap(struct mm_struct *mm)
+{
+ struct xen_hvm_pagetable_dying a;
+ int rc;
+
+ a.domid = DOMID_SELF;
+ a.gpa = __pa(mm->pgd);
+ rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
+ WARN_ON_ONCE(rc < 0);
+}
+
+static int is_pagetable_dying_supported(void)
+{
+ struct xen_hvm_pagetable_dying a;
+ int rc = 0;
+
+ a.domid = DOMID_SELF;
+ a.gpa = 0x00;
+ rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
+ if (rc < 0) {
+ printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
+ return 0;
+ }
+ return 1;
+}
+
+void __init xen_hvm_init_mmu_ops(void)
+{
+ if (is_pagetable_dying_supported())
+ pv_mmu_ops.exit_mmap = xen_hvm_exit_mmap;
+#ifdef CONFIG_PROC_VMCORE
+ register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram);
+#endif
+}