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So, KVM cannot inject exceptions into > a Secure AVIC guest. If KVM were to intercept an exception (e.g., #PF > or #GP), it would be unable to deliver it back to the guest, effectively > dropping the event and leading to guest misbehavior or hangs. So, > clear exception intercepts so that all exceptions are handled directly by > the guest without KVM intervention. > > Signed-off-by: Neeraj Upadhyay > --- > arch/x86/kvm/svm/sev.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index a64fcc7637c7..837ab55a3330 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -4761,8 +4761,17 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) > /* Can't intercept XSETBV, HV can't modify XCR0 directly */ > svm_clr_intercept(svm, INTERCEPT_XSETBV); > > - if (sev_savic_active(vcpu->kvm)) > + if (sev_savic_active(vcpu->kvm)) { > svm_set_intercept_for_msr(vcpu, MSR_AMD64_SAVIC_CONTROL, MSR_TYPE_RW, false); > + > + /* Clear all exception intercepts. */ > + clr_exception_intercept(svm, PF_VECTOR); > + clr_exception_intercept(svm, UD_VECTOR); > + clr_exception_intercept(svm, MC_VECTOR); > + clr_exception_intercept(svm, AC_VECTOR); > + clr_exception_intercept(svm, DB_VECTOR); > + clr_exception_intercept(svm, GP_VECTOR); Some of these are cleared no matter what prior to here. For example, PF_VECTOR is cleared if npt_enabled is true (which is required for SEV), UD_VECTOR and GP_VECTOR are cleared in sev_init_vmcb(). For the MC_VECTOR interception, the SVM code just ignores it today by returning 1 immediately, so clearing the interception looks like a NOP, but I might be missing something. Thanks, Tom > + } > } > > void sev_init_vmcb(struct vcpu_svm *svm)