KVM: SEV: Move SEV's GP_VECTOR intercept setup to SEV

Currently SVM setup is done sequentially in
init_vmcb() -> sev_init_vmcb() -> sev_es_init_vmcb() and tries
keeping SVM/SEV/SEV-ES bits separated. One of the exceptions
is #GP intercept which init_vmcb() skips setting for SEV guests and
then sev_es_init_vmcb() needlessly clears it.

Remove the SEV check from init_vmcb(). Clear the #GP intercept in
sev_init_vmcb(). SEV-ES will use the SEV setting.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Santosh Shukla <santosh.shukla@amd.com>
Link: https://lore.kernel.org/r/20230615063757.3039121-3-aik@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 07756b7..fd6e316 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2974,9 +2974,6 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
        svm_set_intercept(svm, TRAP_CR4_WRITE);
        svm_set_intercept(svm, TRAP_CR8_WRITE);
 
-       /* No support for enable_vmware_backdoor */
-       clr_exception_intercept(svm, GP_VECTOR);
-
        /* Can't intercept XSETBV, HV can't modify XCR0 directly */
        svm_clr_intercept(svm, INTERCEPT_XSETBV);
 
@@ -3002,6 +2999,12 @@ void sev_init_vmcb(struct vcpu_svm *svm)
        svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ENABLE;
        clr_exception_intercept(svm, UD_VECTOR);
 
+       /*
+        * Don't intercept #GP for SEV guests, e.g. for the VMware backdoor, as
+        * KVM can't decrypt guest memory to decode the faulting instruction.
+        */
+       clr_exception_intercept(svm, GP_VECTOR);
+
        if (sev_es_guest(svm->vcpu.kvm))
                sev_es_init_vmcb(svm);
 }

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 42f17ae..a0e803f 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1243,10 +1243,9 @@ 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.  Don't intercept #GP for SEV guests as KVM can't
-        * decrypt guest memory to decode the faulting instruction.
+        * as VMware does.
         */
-       if (enable_vmware_backdoor && !sev_guest(vcpu->kvm))
+       if (enable_vmware_backdoor)
                set_exception_intercept(svm, GP_VECTOR);
 
        svm_set_intercept(svm, INTERCEPT_INTR);