KVM: Introduce {set/get}_interrupt_shadow()

This patch introduces set/get_interrupt_shadow(), that does exactly
what the name suggests. It also replaces open code that explicitly does
it with the now existent functions. It differs slightly from upstream,
because upstream merged it after gleb's interrupt rework, that we don't
ship.

Just for reference, upstream changelog is
(2809f5d2c4cfad171167b131bb2a21ab65eba40f):

This patch replaces drop_interrupt_shadow with the more
general set_interrupt_shadow, that can either drop or raise
it, depending on its parameter.  It also adds ->get_interrupt_shadow()
for future use.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 62 insertions, 10 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a93d1cc413e1..a9471db9b692 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -513,6 +513,8 @@ struct kvm_x86_ops {
 	void (*run)(struct kvm_vcpu *vcpu, struct kvm_run *run);
 	int (*handle_exit)(struct kvm_run *run, 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);
 	void (*patch_hypercall)(struct kvm_vcpu *vcpu,
 				unsigned char *hypercall_addr);
 	int (*get_irq)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/include/asm/kvm_x86_emulate.h b/arch/x86/include/asm/kvm_x86_emulate.h
index 6a159732881a..be40d6e2b6bb 100644
--- a/arch/x86/include/asm/kvm_x86_emulate.h
+++ b/arch/x86/include/asm/kvm_x86_emulate.h
@@ -143,6 +143,9 @@ struct decode_cache {
 	struct fetch_cache fetch;
 };
 
+#define X86_SHADOW_INT_MOV_SS  1
+#define X86_SHADOW_INT_STI     2
+
 struct x86_emulate_ctxt {
 	/* Register state before/after emulation. */
 	struct kvm_vcpu *vcpu;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1f8510c51d6e..0f10a69a18a2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -227,6 +227,27 @@ 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)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+	u32 ret = 0;
+
+	if (svm->vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK)
+		ret |= X86_SHADOW_INT_STI | X86_SHADOW_INT_MOV_SS;
+	return ret & mask;
+}
+
+static void svm_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+
+	if (mask == 0)
+		svm->vmcb->control.int_state &= ~SVM_INTERRUPT_SHADOW_MASK;
+	else
+		svm->vmcb->control.int_state |= SVM_INTERRUPT_SHADOW_MASK;
+
+}
+
 static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
@@ -240,7 +261,7 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 		       __func__, kvm_rip_read(vcpu), svm->next_rip);
 
 	kvm_rip_write(vcpu, svm->next_rip);
-	svm->vmcb->control.int_state &= ~SVM_INTERRUPT_SHADOW_MASK;
+	svm_set_interrupt_shadow(vcpu, 0);
 
 	vcpu->arch.interrupt_window_open = (svm->vcpu.arch.hflags & HF_GIF_MASK);
 }
@@ -2667,6 +2688,8 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.run = svm_vcpu_run,
 	.handle_exit = handle_exit,
 	.skip_emulated_instruction = skip_emulated_instruction,
+	.set_interrupt_shadow = svm_set_interrupt_shadow,
+	.get_interrupt_shadow = svm_get_interrupt_shadow,
 	.patch_hypercall = svm_patch_hypercall,
 	.get_irq = svm_get_irq,
 	.set_irq = svm_set_irq,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fa0adcd8a36f..1a0d5cdd1a10 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -732,23 +732,45 @@ 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)
+{
+	u32 interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
+	int ret = 0;
+
+	if (interruptibility & GUEST_INTR_STATE_STI)
+		ret |= X86_SHADOW_INT_STI;
+	if (interruptibility & GUEST_INTR_STATE_MOV_SS)
+		ret |= X86_SHADOW_INT_MOV_SS;
+
+	return ret & mask;
+}
+
+static void vmx_set_interrupt_shadow(struct kvm_vcpu *vcpu, int mask)
+{
+	u32 interruptibility_old = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
+	u32 interruptibility = interruptibility_old;
+
+	interruptibility &= ~(GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS);
+
+	if (mask & X86_SHADOW_INT_MOV_SS)
+		interruptibility |= GUEST_INTR_STATE_MOV_SS;
+	if (mask & X86_SHADOW_INT_STI)
+		interruptibility |= GUEST_INTR_STATE_STI;
+
+	if ((interruptibility != interruptibility_old))
+		vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, interruptibility);
+}
+
 static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 {
 	unsigned long rip;
-	u32 interruptibility;
 
 	rip = kvm_rip_read(vcpu);
 	rip += vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
 	kvm_rip_write(vcpu, rip);
 
-	/*
-	 * We emulated an instruction, so temporary interrupt blocking
-	 * should be removed, if set.
-	 */
-	interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
-	if (interruptibility & 3)
-		vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
-			     interruptibility & ~3);
+	/* skipping an emulated instruction also counts */
+	vmx_set_interrupt_shadow(vcpu, 0);
 	vcpu->arch.interrupt_window_open = 1;
 }
 
@@ -3738,6 +3760,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.run = vmx_vcpu_run,
 	.handle_exit = kvm_handle_exit,
 	.skip_emulated_instruction = skip_emulated_instruction,
+	.set_interrupt_shadow = vmx_set_interrupt_shadow,
+	.get_interrupt_shadow = vmx_get_interrupt_shadow,
 	.patch_hypercall = vmx_patch_hypercall,
 	.get_irq = vmx_get_irq,
 	.set_irq = vmx_inject_irq,