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,
Babu Moger <babu.moger@amd.com>,
Joao Martins <joao.m.martins@oracle.com>,
David Woodhouse <dwmw@amazon.co.uk>
Subject: [PATCH v2 2/9] KVM: x86: Check CR3 GPA for validity regardless of vCPU mode
Date: Wed, 21 Apr 2021 19:21:21 -0700 [thread overview]
Message-ID: <20210422022128.3464144-3-seanjc@google.com> (raw)
In-Reply-To: <20210422022128.3464144-1-seanjc@google.com>
Check CR3 for an invalid GPA even if the vCPU isn't in long mode. For
bigger emulation flows, notably RSM, the vCPU mode may not be accurate
if CR0/CR4 are loaded after CR3. For MOV CR3 and similar flows, the
caller is responsible for truncating the value.
Note, SMRAM.CR3 is read-only, so this is mostly a theoretical bug since
KVM will not have stored an illegal CR3 into SMRAM during SMI emulation.
Fixes: 660a5d517aaa ("KVM: x86: save/load state on SMM switch")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/x86.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c9ba6f2d9bcd..63af93211871 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1078,10 +1078,15 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
return 0;
}
- if (is_long_mode(vcpu) && kvm_vcpu_is_illegal_gpa(vcpu, cr3))
+ /*
+ * Do not condition the GPA check on long mode, this helper is used to
+ * stuff CR3, e.g. for RSM emulation, and there is no guarantee that
+ * the current vCPU mode is accurate.
+ */
+ if (kvm_vcpu_is_illegal_gpa(vcpu, cr3))
return 1;
- else if (is_pae_paging(vcpu) &&
- !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
+
+ if (is_pae_paging(vcpu) && !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
return 1;
kvm_mmu_new_pgd(vcpu, cr3, skip_tlb_flush, skip_tlb_flush);
--
2.31.1.498.g6c1eba8ee3d-goog
next prev parent reply other threads:[~2021-04-22 2:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 2:21 [PATCH v2 0/9] KVM: x86: Fixes for (benign?) truncation bugs Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 1/9] KVM: x86: Remove emulator's broken checks on CR0/CR3/CR4 loads Sean Christopherson
2021-04-22 6:50 ` Paolo Bonzini
2021-04-22 2:21 ` Sean Christopherson [this message]
2021-04-22 6:51 ` [PATCH v2 2/9] KVM: x86: Check CR3 GPA for validity regardless of vCPU mode Paolo Bonzini
2021-04-22 16:55 ` Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 3/9] KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 4/9] KVM: VMX: Truncate GPR value for DR and CR reads " Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 5/9] KVM: nVMX: Truncate bits 63:32 of VMCS field on nested check in !64-bit Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 6/9] KVM: nVMX: Truncate base/index GPR value on address calc " Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 7/9] KVM: x86/xen: Drop RAX[63:32] when processing hypercall Sean Christopherson
2021-04-22 9:51 ` Vitaly Kuznetsov
2021-04-22 10:35 ` Paolo Bonzini
2021-04-22 10:49 ` Vitaly Kuznetsov
2021-04-22 2:21 ` [PATCH v2 8/9] KVM: SVM: Use default rAX size for INVLPGA emulation Sean Christopherson
2021-04-22 2:21 ` [PATCH v2 9/9] KVM: x86: Rename GPR accessors to make mode-aware variants the defaults Sean Christopherson
2021-04-22 6:55 ` [PATCH v2 0/9] KVM: x86: Fixes for (benign?) truncation bugs Paolo Bonzini
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