From 6f3e157e21b24d38c4a5d76cc40ddd4fdeb74d18 Mon Sep 17 00:00:00 2001 From: Denis Valeev Date: Sat, 22 Jan 2022 23:13:57 +0300 Subject: [PATCH] KVM: x86: nSVM: skip eax alignment check for non-SVM instructions commit 47c28d436f409f5b009dc82bd82d4971088aa391 upstream. 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: d1cba6c92237 ("KVM: x86: nSVM: test eax for 4K alignment for GP errata workaround") Signed-off-by: Denis Valeev Message-Id: Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/svm.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e65755d6c247c..da33ec9bb26e8 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2238,10 +2238,6 @@ 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; @@ -2259,8 +2255,13 @@ 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); -- 2.30.2