KVM: x86: emulate #UD while in guest mode

This reverts commits ae1f57670703656cc9f293722c3b8b6782f8ab3f
and ac9b305caa0df6f5b75d294e4b86c1027648991e.

If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE
in L1's emulated CPUID information, then L1 is likely to pass that
CPUID bit through to L2. L2 will expect MOVBE to work, but if L1
doesn't intercept #UD, then any MOVBE instruction executed in L2 will
raise #UD, and the exception will be delivered in L2.

Commit ac9b305caa0df6f5b75d294e4b86c1027648991e is a better and more
complete version of ae1f57670703 ("KVM: nVMX: Do not emulate #UD while
in guest mode"); however, neither considers the above case.

Suggested-by: Jim Mattson <jmattson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index bb31c801f1fc9d45c1dc629bd9c056769584530a..3158dac87f8227c528a586b8acdcc9bcb0357dc2 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -361,7 +361,6 @@ 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);
 
@@ -372,14 +371,9 @@ 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;
 }
 
@@ -2202,7 +2196,6 @@ 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_USER_EXIT)
                return 0;

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5c14d65f676a99028b21108e272b9aa44bfe351c..427fd3200dd8c51ff12e18422282a855d5b22a9f 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 << MC_VECTOR) |
+       eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
             (1u << DB_VECTOR) | (1u << AC_VECTOR);
        if ((vcpu->guest_debug &
             (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
@@ -1905,8 +1905,6 @@ 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);
 }
@@ -5917,7 +5915,6 @@ static int handle_exception(struct kvm_vcpu *vcpu)
                return 1;  /* already handled by vmx_vcpu_run() */
 
        if (is_invalid_opcode(intr_info)) {
-               WARN_ON_ONCE(is_guest_mode(vcpu));
                er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);
                if (er == EMULATE_USER_EXIT)
                        return 0;