diff mbox series

[kvm-unit-tests,14/39] x86/access: Don't write page tables if desired PTE is same as current PTE

Message ID 20211125012857.508243-15-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series x86/access: nVMX: Big overhaul | expand

Commit Message

Sean Christopherson Nov. 25, 2021, 1:28 a.m. UTC 
Avoid spurious PTE writes, KVM doesn't check if old==new when handling
write-protected SPTEs and triggers an MMU sync when using shadow paging
even if the SPTE is unchanged.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 x86/access.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/x86/access.c b/x86/access.c
index abc6590..53b1221 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -704,7 +704,8 @@  static void __ac_setup_specific_pages(ac_test_t *at, u64 pd_page, u64 pt_page)
 			assert(0);
 		}
 
-		*ptep = pte;
+		if (pte != *ptep)
+			*ptep = pte;
 
 		parent_pte = pte;
 	}