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

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 ae1f57670703 ("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>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 59e13a79c2e3eea5588be38d3fdb677cf9076b3d..1bf7c09d97e61099f1e1be735db1ecee3acb6647 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -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);

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 714a0673ec3cb2153dce2f192f412fc14e0d19df..d319e2666ad586252511e3329e6fcd4be703f9db 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1887,7 +1887,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
 {
        u32 eb;
 
-       eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
+       eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) |
             (1u << DB_VECTOR) | (1u << AC_VECTOR);
        if ((vcpu->guest_debug &
             (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
@@ -1905,6 +1905,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
         */
        if (is_guest_mode(vcpu))
                eb |= get_vmcs12(vcpu)->exception_bitmap;
+       else
+               eb |= 1u << UD_VECTOR;
 
        vmcs_write32(EXCEPTION_BITMAP, eb);
 }
@@ -5915,10 +5917,7 @@ static int handle_exception(struct kvm_vcpu *vcpu)
                return 1;  /* already handled by vmx_vcpu_run() */
 
        if (is_invalid_opcode(intr_info)) {
-               if (is_guest_mode(vcpu)) {
-                       kvm_queue_exception(vcpu, UD_VECTOR);
-                       return 1;
-               }
+               WARN_ON_ONCE(is_guest_mode(vcpu));
                er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
                if (er != EMULATE_DONE)
                        kvm_queue_exception(vcpu, UD_VECTOR);