diff mbox series

[v2,1/8] Revert "KVM: Do not speculatively mark pfn cache valid to "fix" race"

Message ID 20220427014004.1992589-2-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: Fix mmu_notifier vs. pfncache vs. pfncache races | expand

Commit Message

Sean Christopherson April 27, 2022, 1:39 a.m. UTC 
This reverts commit 55111927df1cd140aa7b7ea3f33f524b87776381.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 virt/kvm/pfncache.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 72eee096a7cd..71c84a43024c 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -81,8 +81,6 @@  bool kvm_gfn_to_pfn_cache_check(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
 {
 	struct kvm_memslots *slots = kvm_memslots(kvm);
 
-	lockdep_assert_held_read(&gpc->lock);
-
 	if ((gpa & ~PAGE_MASK) + len > PAGE_SIZE)
 		return false;
 
@@ -228,6 +226,11 @@  int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
 	if (!old_valid || old_uhva != gpc->uhva) {
 		void *new_khva = NULL;
 
+		/* Placeholders for "hva is valid but not yet mapped" */
+		gpc->pfn = KVM_PFN_ERR_FAULT;
+		gpc->khva = NULL;
+		gpc->valid = true;
+
 		new_pfn = hva_to_pfn_retry(kvm, gpc);
 		if (is_error_noslot_pfn(new_pfn)) {
 			ret = -EFAULT;
@@ -256,7 +259,7 @@  int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
 			gpc->pfn = KVM_PFN_ERR_FAULT;
 			gpc->khva = NULL;
 		} else {
-			gpc->valid = true;
+			/* At this point, gpc->valid may already have been cleared */
 			gpc->pfn = new_pfn;
 			gpc->khva = new_khva;
 		}