KVM: x86: return all bits from get_interrupt_shadow

For the next patch we will need to know the full state of the
interrupt shadow; we will then set KVM_REQ_EVENT when one bit
is cleared.

However, right now get_interrupt_shadow only returns the one
corresponding to the emulated instruction, or an unconditional
0 if the emulated instruction does not have an interrupt shadow.
This is confusing and does not allow us to check for cleared
bits as mentioned above.

Clean the callback up, and modify toggle_interruptibility to
match the comment above the call.  As a small result, the
call to set_interrupt_shadow will be skipped in the common
case where int_shadow == 0 && mask == 0.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -717,7 +717,7 @@ struct kvm_x86_ops {
 	int (*handle_exit)(struct kvm_vcpu *vcpu);
 	void (*skip_emulated_instruction)(struct kvm_vcpu *vcpu);
 	void (*set_interrupt_shadow)(struct kvm_vcpu *vcpu, int mask);
-	u32 (*get_interrupt_shadow)(struct kvm_vcpu *vcpu, int mask);
+	u32 (*get_interrupt_shadow)(struct kvm_vcpu *vcpu);
 	void (*patch_hypercall)(struct kvm_vcpu *vcpu,
 				unsigned char *hypercall_addr);
 	void (*set_irq)(struct kvm_vcpu *vcpu);

arch/x86/kvm/svm.c

@@ -486,14 +486,14 @@ static int is_external_interrupt(u32 info)
 	return info == (SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR);
 }
 
-static u32 svm_get_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
+static u32 svm_get_interrupt_shadow(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	u32 ret = 0;
 
 	if (svm->vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK)
-		ret |= KVM_X86_SHADOW_INT_STI | KVM_X86_SHADOW_INT_MOV_SS;
-	return ret & mask;
+		ret = KVM_X86_SHADOW_INT_STI | KVM_X86_SHADOW_INT_MOV_SS;
+	return ret;
 }
 
 static void svm_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)

arch/x86/kvm/vmx.c

@@ -1943,7 +1943,7 @@ static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
 	vmcs_writel(GUEST_RFLAGS, rflags);
 }
 
-static u32 vmx_get_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
+static u32 vmx_get_interrupt_shadow(struct kvm_vcpu *vcpu)
 {
 	u32 interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
 	int ret = 0;
@@ -1953,7 +1953,7 @@ static u32 vmx_get_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
 	if (interruptibility & GUEST_INTR_STATE_MOV_SS)
 		ret |= KVM_X86_SHADOW_INT_MOV_SS;
 
-	return ret & mask;
+	return ret;
 }
 
 static void vmx_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)

arch/x86/kvm/x86.c

@@ -2978,9 +2978,7 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 		vcpu->arch.interrupt.pending && !vcpu->arch.interrupt.soft;
 	events->interrupt.nr = vcpu->arch.interrupt.nr;
 	events->interrupt.soft = 0;
-	events->interrupt.shadow =
-		kvm_x86_ops->get_interrupt_shadow(vcpu,
-			KVM_X86_SHADOW_INT_MOV_SS | KVM_X86_SHADOW_INT_STI);
+	events->interrupt.shadow = kvm_x86_ops->get_interrupt_shadow(vcpu);
 
 	events->nmi.injected = vcpu->arch.nmi_injected;
 	events->nmi.pending = vcpu->arch.nmi_pending != 0;
@@ -4860,7 +4858,7 @@ static const struct x86_emulate_ops emulate_ops = {
 
 static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
 {
-	u32 int_shadow = kvm_x86_ops->get_interrupt_shadow(vcpu, mask);
+	u32 int_shadow = kvm_x86_ops->get_interrupt_shadow(vcpu);
 	/*
 	 * an sti; sti; sequence only disable interrupts for the first
 	 * instruction. So, if the last instruction, be it emulated or
@@ -4868,7 +4866,9 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
 	 * means that the last instruction is an sti. We should not
 	 * leave the flag on in this case. The same goes for mov ss
 	 */
-	if (!(int_shadow & mask))
+	if (int_shadow & mask)
+		mask = 0;
+	if (unlikely(int_shadow || mask))
 		kvm_x86_ops->set_interrupt_shadow(vcpu, mask);
 }