From: Sean Christopherson Date: Fri, 5 Mar 2021 01:10:52 +0000 (-0800) Subject: KVM: x86/mmu: Fix and unconditionally enable WARNs to detect PAE leaks X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e49e0b7bf370ebed369f7f0466f349aac5ff12f1;p=linux.git KVM: x86/mmu: Fix and unconditionally enable WARNs to detect PAE leaks Exempt NULL PAE roots from the check to detect leaks, since kvm_mmu_free_roots() doesn't set them back to INVALID_PAGE. Stop hiding the WARNs to detect PAE root leaks behind MMU_WARN_ON, the hidden WARNs obviously didn't do their job given the hilarious number of bugs that could lead to PAE roots being leaked, not to mention the above false positive. Opportunistically delete a warning on root_hpa being valid, there's nothing special about 4/5-level shadow pages that warrants a WARN. Signed-off-by: Sean Christopherson Message-Id: <20210305011101.3597423-9-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index fa74b647cab7b..da94734272db1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3256,7 +3256,8 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) mmu->root_hpa = root; } else if (shadow_root_level == PT32E_ROOT_LEVEL) { for (i = 0; i < 4; ++i) { - MMU_WARN_ON(VALID_PAGE(mmu->pae_root[i])); + WARN_ON_ONCE(mmu->pae_root[i] && + VALID_PAGE(mmu->pae_root[i])); root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i << 30, PT32_ROOT_LEVEL, true); @@ -3302,8 +3303,6 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) * write-protect the guests page table root. */ if (mmu->root_level >= PT64_ROOT_4LEVEL) { - MMU_WARN_ON(VALID_PAGE(mmu->root_hpa)); - root = mmu_alloc_root(vcpu, root_gfn, 0, mmu->shadow_root_level, false); mmu->root_hpa = root; @@ -3323,7 +3322,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) } for (i = 0; i < 4; ++i) { - MMU_WARN_ON(VALID_PAGE(mmu->pae_root[i])); + WARN_ON_ONCE(mmu->pae_root[i] && VALID_PAGE(mmu->pae_root[i])); if (mmu->root_level == PT32E_ROOT_LEVEL) { if (!(pdptrs[i] & PT_PRESENT_MASK)) {