diff options
| author |   Sean Christopherson <seanjc@google.com> | 2022-01-20 01:07:19 +0000 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2022-01-26 12:15:02 -0500 |
| commit | cdf85e0c5dc766fc7fc779466280e454a6d04f87 (patch) | |
| tree | 436f0d0cf7a1142c9edbe2c82d0ddce470d1d84c /arch | |
| parent | KVM: SVM: Don't apply SEV+SMAP workaround on code fetch or PT access (diff) | |
| download | linux-dev-cdf85e0c5dc766fc7fc779466280e454a6d04f87.tar.xz linux-dev-cdf85e0c5dc766fc7fc779466280e454a6d04f87.zip | |
KVM: SVM: Don't kill SEV guest if SMAP erratum triggers in usermode
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.
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index be25831830b0..f14f4ab97a80 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4360,7 +4360,21 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type, 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); + else + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); } resume_guest: |