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Subject[PATCH 3/9] KVM: SVM: Don't intercept #GP for SEV guests
From
Never intercept #GP for SEV guests as reading SEV guest private memory
will return cyphertext, i.e. emulating on #GP can't work as intended.

Cc: stable@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/svm.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 85703145eb0a..edea52be6c01 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -312,7 +312,11 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
return ret;
}

- if (svm_gp_erratum_intercept)
+ /*
+ * Never intercept #GP for SEV guests, KVM can't
+ * decrypt guest memory to workaround the erratum.
+ */
+ if (svm_gp_erratum_intercept && !sev_guest(vcpu->kvm))
set_exception_intercept(svm, GP_VECTOR);
}
}
@@ -1010,9 +1014,10 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
* Guest access to VMware backdoor ports could legitimately
* trigger #GP because of TSS I/O permission bitmap.
* We intercept those #GP and allow access to them anyway
- * as VMware does.
+ * as VMware does. Don't intercept #GP for SEV guests as KVM can't
+ * decrypt guest memory to decode the faulting instruction.
*/
- if (enable_vmware_backdoor)
+ if (enable_vmware_backdoor && !sev_guest(vcpu->kvm))
set_exception_intercept(svm, GP_VECTOR);

svm_set_intercept(svm, INTERCEPT_INTR);
--
2.34.1.703.g22d0c6ccf7-goog
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