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

@@ -160,6 +160,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp, · 159 unmodified lines
160	160
161	161	extern void prep_transhuge_page(struct page *page);
162	162	extern void free_transhuge_page(struct page *page);
	163	+bool is_transparent_hugepage(struct page *page);
163	164
164	165	bool can_split_huge_page(struct page page, int pextra_pins);
165	166	int split_huge_page_to_list(struct page page, struct list_head list);
@@ -308,6 +309,11 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, · 142 unmodified lines
308	309
309	310	static inline void prep_transhuge_page(struct page *page) {}
310	311
	312	+static inline bool is_transparent_hugepage(struct page *page)
	313	+{
	314	+ return false;
	315	+}
	316	+
311	317	#define transparent_hugepage_flags 0UL
312	318
313	319	#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	977	bool kvm_is_reserved_pfn(kvm_pfn_t pfn);
978	978	bool kvm_is_zone_device_pfn(kvm_pfn_t pfn);
	979	+bool kvm_is_transparent_hugepage(kvm_pfn_t pfn);
979	980
980	981	struct kvm_irq_ack_notifier {
981	982	struct hlist_node link;