mm: thp: KVM: Explicitly check for THP when populating secondary MMU

Add a helper, is_transparent_hugepage(), to explicitly check whether a compound page is a THP and use it when populating KVM's secondary MMU. The explicit check fixes a bug where a remapped compound page, e.g. for an XDP Rx socket, is mapped into a KVM guest and is mistaken for a THP, which results in KVM incorrectly creating a huge page in its secondary MMU.

Sean Christopherson committed 6 years ago

Commit 005ba371 parent 22b1d576 files · +31 −9Browse files

Showing the changes to include/linux (2 of 6 files). Show all

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2 files

include/linux/huge_mm.h +6 −0
include/linux/kvm_host.h +1 −0

include/linux/huge_mm.h+6−0

 extern void prep_transhuge_page(struct page *page);
 extern void free_transhuge_page(struct page *page);
+bool is_transparent_hugepage(struct page *page);
 bool can_split_huge_page(struct page *page, int *pextra_pins);
 int split_huge_page_to_list(struct page *page, struct list_head *list);
 static inline void prep_transhuge_page(struct page *page) {}
+static inline bool is_transparent_hugepage(struct page *page)
+{
+	return false;
+}
 #define transparent_hugepage_flags 0UL
 #define thp_get_unmapped_area	NULL

include/linux/kvm_host.h+1−0

@@ -976,6 +976,7 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu); · 975 unmodified lines
976		976
977	bool kvm_is_reserved_pfn(kvm_pfn_t pfn);	977	bool kvm_is_reserved_pfn(kvm_pfn_t pfn);
978	bool kvm_is_zone_device_pfn(kvm_pfn_t pfn);	978	bool kvm_is_zone_device_pfn(kvm_pfn_t pfn);
		979	bool kvm_is_transparent_hugepage(kvm_pfn_t pfn);
979		980
980	struct kvm_irq_ack_notifier {	981	struct kvm_irq_ack_notifier {
981	struct hlist_node link;	982	struct hlist_node link;