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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ben Gardon <bgardon@google.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>
Subject: [PATCH v2 07/17] KVM: x86/mmu: Check PDPTRs before allocating PAE roots
Date: Thu,  4 Mar 2021 17:10:51 -0800	[thread overview]
Message-ID: <20210305011101.3597423-8-seanjc@google.com> (raw)
In-Reply-To: <20210305011101.3597423-1-seanjc@google.com>

Check the validity of the PDPTRs before allocating any of the PAE roots,
otherwise a bad PDPTR will cause KVM to leak any previously allocated
roots.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 7ebfbc77b050..9fc2b46f8541 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3269,7 +3269,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
 static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
-	u64 pdptr, pm_mask;
+	u64 pdptrs[4], pm_mask;
 	gfn_t root_gfn, root_pgd;
 	hpa_t root;
 	int i;
@@ -3280,6 +3280,17 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 	if (mmu_check_root(vcpu, root_gfn))
 		return 1;
 
+	if (mmu->root_level == PT32E_ROOT_LEVEL) {
+		for (i = 0; i < 4; ++i) {
+			pdptrs[i] = mmu->get_pdptr(vcpu, i);
+			if (!(pdptrs[i] & PT_PRESENT_MASK))
+				continue;
+
+			if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT))
+				return 1;
+		}
+	}
+
 	/*
 	 * Do we shadow a long mode page table? If so we need to
 	 * write-protect the guests page table root.
@@ -3309,14 +3320,11 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 		MMU_WARN_ON(VALID_PAGE(mmu->pae_root[i]));
 
 		if (mmu->root_level == PT32E_ROOT_LEVEL) {
-			pdptr = mmu->get_pdptr(vcpu, i);
-			if (!(pdptr & PT_PRESENT_MASK)) {
+			if (!(pdptrs[i] & PT_PRESENT_MASK)) {
 				mmu->pae_root[i] = 0;
 				continue;
 			}
-			root_gfn = pdptr >> PAGE_SHIFT;
-			if (mmu_check_root(vcpu, root_gfn))
-				return 1;
+			root_gfn = pdptrs[i] >> PAGE_SHIFT;
 		}
 
 		root = mmu_alloc_root(vcpu, root_gfn, i << 30,
-- 
2.30.1.766.gb4fecdf3b7-goog


  parent reply	other threads:[~2021-03-05  1:11 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-05  1:10 [PATCH v2 00/17] KVM: x86/mmu: Lots of bug fixes Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 01/17] KVM: nSVM: Set the shadow root level to the TDP level for nested NPT Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 02/17] KVM: x86/mmu: Alloc page for PDPTEs when shadowing 32-bit NPT with 64-bit Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 03/17] KVM: x86/mmu: Capture 'mmu' in a local variable when allocating roots Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 04/17] KVM: x86/mmu: Allocate the lm_root before allocating PAE roots Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 05/17] KVM: x86/mmu: Allocate pae_root and lm_root pages in dedicated helper Sean Christopherson
2021-03-05 17:34   ` Paolo Bonzini
2021-03-05  1:10 ` [PATCH v2 06/17] KVM: x86/mmu: Ensure MMU pages are available when allocating roots Sean Christopherson
2021-03-05  1:10 ` Sean Christopherson [this message]
2021-04-08 11:15   ` [PATCH v2 07/17] KVM: x86/mmu: Check PDPTRs before allocating PAE roots Wanpeng Li
2021-04-08 12:09     ` Paolo Bonzini
2021-04-08 15:48       ` Sean Christopherson
2021-04-08 15:57         ` Paolo Bonzini
2021-04-08 16:27           ` Sean Christopherson
2021-04-08 16:30             ` Paolo Bonzini
2021-03-05  1:10 ` [PATCH v2 08/17] KVM: x86/mmu: Fix and unconditionally enable WARNs to detect PAE leaks Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 09/17] KVM: x86/mmu: Use '0' as the one and only value for an invalid PAE root Sean Christopherson
2021-03-05 17:52   ` Paolo Bonzini
2021-03-05 18:22     ` Sean Christopherson
2021-03-05 18:23       ` Paolo Bonzini
2021-03-05  1:10 ` [PATCH v2 10/17] KVM: x86/mmu: Set the C-bit in the PDPTRs and LM pseudo-PDPTRs Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 11/17] KVM: x86/mmu: Mark the PAE roots as decrypted for shadow paging Sean Christopherson
2021-03-05 17:44   ` Paolo Bonzini
2021-03-05 18:02     ` Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 12/17] KVM: SVM: Don't strip the C-bit from CR2 on #PF interception Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 13/17] KVM: nVMX: Defer the MMU reload to the normal path on an EPTP switch Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 14/17] KVM: x86: Defer the MMU unload to the normal path on an global INVPCID Sean Christopherson
2021-03-05  1:10 ` [PATCH v2 15/17] KVM: x86/mmu: Unexport MMU load/unload functions Sean Christopherson
2021-03-05  1:11 ` [PATCH v2 16/17] KVM: x86/mmu: Sync roots after MMU load iff load as successful Sean Christopherson
2021-03-05  1:11 ` [PATCH v2 17/17] KVM: x86/mmu: WARN on NULL pae_root or lm_root, or bad shadow root level Sean Christopherson
2021-03-05 17:53 ` [PATCH v2 00/17] KVM: x86/mmu: Lots of bug fixes Paolo Bonzini

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