Commit 51dddf6c authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Sean Christopherson
Browse files

KVM: x86/mmu: Check mmu->sync_page pointer in kvm_sync_page_check() 



Assert that mmu->sync_page is non-NULL as part of the sanity checks
performed before attempting to sync a shadow page.  Explicitly checking
mmu->sync_page is all but guaranteed to be redundant with the existing
sanity check that the MMU is indirect, but the cost is negligible, and
the explicit check also serves as documentation.

Signed-off-by: default avatarLai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216154115.710033-4-jiangshanlai@gmail.com


[sean: increase verbosity of changelog]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 90e44470

arch/x86/kvm/mmu/mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -1940,7 +1940,7 @@ static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
	 * differs then the memslot lookup (SMM vs. non-SMM) will be bogus, the

	 * reserved bits checks will be wrong, etc...

	 */

	if (WARN_ON_ONCE(sp->role.direct ||

	if (WARN_ON_ONCE(sp->role.direct || !vcpu->arch.mmu->sync_page ||

			 (sp->role.word ^ root_role.word) & ~sync_role_ign.word))

		return false;