On 2/9/22 19:56, Sasha Levin wrote:
From: Sean Christopherson seanjc@google.com
[ Upstream commit cdf85e0c5dc766fc7fc779466280e454a6d04f87 ]
Inject a #GP instead of synthesizing triple fault to try to avoid killing the guest if emulation of an SEV guest fails due to encountering the SMAP erratum. The injected #GP may still be fatal to the guest, e.g. if the userspace process is providing critical functionality, but KVM should make every attempt to keep the guest alive.
Acked-by: Paolo Bonzini pbonzini@redhat.com
Paolo
Signed-off-by: Sean Christopherson seanjc@google.com Reviewed-by: Liam Merwick liam.merwick@oracle.com Message-Id: 20220120010719.711476-10-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org
arch/x86/kvm/svm/svm.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 3efada37272c0..d6a4acaa65742 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4530,7 +4530,21 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int i is_user = svm_get_cpl(vcpu) == 3; if (smap && (!smep || is_user)) { pr_err_ratelimited("KVM: SEV Guest triggered AMD Erratum 1096\n");
kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
/** If the fault occurred in userspace, arbitrarily inject #GP* to avoid killing the guest and to hopefully avoid confusing* the guest kernel too much, e.g. injecting #PF would not be* coherent with respect to the guest's page tables. Request* triple fault if the fault occurred in the kernel as there's* no fault that KVM can inject without confusing the guest.* In practice, the triple fault is moot as no sane SEV kernel* will execute from user memory while also running with SMAP=1.*/if (is_user)kvm_inject_gp(vcpu, 0);elsekvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);return false;