From: Denis Valeev lemniscattaden@gmail.com
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 lemniscattaden@gmail.com Message-Id: Yexlhaoe1Fscm59u@q Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/svm/svm.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2306,10 +2306,6 @@ static int gp_interception(struct kvm_vc 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; @@ -2327,8 +2323,13 @@ static int gp_interception(struct kvm_vc 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);