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>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 5c7bbde..0c9569b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1943,7 +1943,7 @@
 	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 @@
 	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)