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KVM: nVMX/nSVM: Don't intercept #UD when running L2

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When running L2, #UD should be intercepted by L1 or just forwarded
directly to L2. It should not reach L0 x86 emulator.
Therefore, set intercept for #UD only based on L1 exception-bitmap.

Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure
it is never reached while running L2.

This improves commit ae1f576707 ("KVM: nVMX: Do not emulate #UD while
in guest mode") by removing an unnecessary exit from L2 to L0 on #UD
when L1 doesn't intercept it.

In addition, SVM L0 #UD intercept handler doesn't handle correctly the
case it is raised from L2. In this case, it should forward the #UD to
guest instead of x86 emulator. As done in VMX #UD intercept handler.
This commit fixes this issue as-well.

Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Liran Alon
2017-11-06 16:15:10 +02:00
committed by Paolo Bonzini
parent 51c4b8bba6
commit ac9b305caa
2 changed files with 12 additions and 6 deletions
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9
arch/x86/kvm/svm.c
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@@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm)
{
struct vmcb_control_area *c, *h;
struct nested_state *g;
u32 h_intercept_exceptions;
mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
@@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm)
h = &svm->nested.hsave->control;
g = &svm->nested;
/* No need to intercept #UD if L1 doesn't intercept it */
h_intercept_exceptions =
h->intercept_exceptions & ~(1U << UD_VECTOR);
c->intercept_cr = h->intercept_cr | g->intercept_cr;
c->intercept_dr = h->intercept_dr | g->intercept_dr;
c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;
c->intercept_exceptions =
h_intercept_exceptions | g->intercept_exceptions;
c->intercept = h->intercept | g->intercept;
}
@@ -2196,6 +2202,7 @@ static int ud_interception(struct vcpu_svm *svm)
{
int er;
WARN_ON_ONCE(is_guest_mode(&svm->vcpu));
er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);
if (er != EMULATE_DONE)
kvm_queue_exception(&svm->vcpu, UD_VECTOR);