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KVM: x86: nSVM: skip eax alignment check for non-SVM instructions

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The bug occurs on #GP triggered by VMware backdoor when eax value is
unaligned. eax alignment check should not be applied to non-SVM
instructions because it leads to incorrect omission of the instructions
emulation.
Apply the alignment check only to SVM instructions to fix.

Fixes: d1cba6c922 ("KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround")
Signed-off-by: Denis Valeev <lemniscattaden@gmail.com>
Message-Id: <Yexlhaoe1Fscm59u@q>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Denis Valeev 2022-01-22 23:13:57 +03:00 committed by Paolo Bonzini
parent 1ffce0924a
commit 47c28d436f
1 changed files with 6 additions and 5 deletions
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11
arch/x86/kvm/svm/svm.c
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@ -2091,10 +2091,6 @@ static int gp_interception(struct kvm_vcpu *vcpu)
if (error_code)
goto reinject;
/* All SVM instructions expect page aligned RAX */
if (svm->vmcb->save.rax & ~PAGE_MASK)
goto reinject;
/* Decode the instruction for usage later */
if (x86_decode_emulated_instruction(vcpu, 0, NULL, 0) != EMULATION_OK)
goto reinject;
@ -2112,8 +2108,13 @@ static int gp_interception(struct kvm_vcpu *vcpu)
if (!is_guest_mode(vcpu))
return kvm_emulate_instruction(vcpu,
EMULTYPE_VMWARE_GP | EMULTYPE_NO_DECODE);
} else
} else {
/* All SVM instructions expect page aligned RAX */
if (svm->vmcb->save.rax & ~PAGE_MASK)
goto reinject;
return emulate_svm_instr(vcpu, opcode);
}
reinject:
kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);