From 51dddf6c49b9f60341a80c4947f3be67b3d50dc0 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan <jiangshan.ljs@antgroup.com> Date: Thu, 16 Feb 2023 23:41:09 +0800 Subject: [PATCH] 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: Lai 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: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/mmu/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 6749fa4794a4..9d31724d26ad 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -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; -- 2.49.0