---

yaml
---
r: 146584
b: refs/heads/master
c: 310b5d3
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2809f5d2c4cfad171167b131bb2a21ab65eba40f
+refs/heads/master: 310b5d306c1aee7ebe32f702c0e33e7988d50646

trunk/arch/x86/include/asm/kvm_x86_emulate.h

@@ -155,6 +155,9 @@ struct x86_emulate_ctxt {
 	int mode;
 	u32 cs_base;
 
+	/* interruptibility state, as a result of execution of STI or MOV SS */
+	int interruptibility;
+
 	/* decode cache */
 	struct decode_cache decode;
 };

trunk/arch/x86/kvm/x86.c

@@ -2379,7 +2379,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 			u16 error_code,
 			int emulation_type)
 {
-	int r;
+	int r, shadow_mask;
 	struct decode_cache *c;
 
 	kvm_clear_exception_queue(vcpu);
@@ -2433,6 +2433,10 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 	}
 
 	r = x86_emulate_insn(&vcpu->arch.emulate_ctxt, &emulate_ops);
+	shadow_mask = vcpu->arch.emulate_ctxt.interruptibility;
+
+	if (r == 0)
+		kvm_x86_ops->set_interrupt_shadow(vcpu, shadow_mask);
 
 	if (vcpu->arch.pio.string)
 		return EMULATE_DO_MMIO;

trunk/arch/x86/kvm/x86_emulate.c

@@ -1361,6 +1361,20 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
 	return 0;
 }
 
+void toggle_interruptibility(struct x86_emulate_ctxt *ctxt, u32 mask)
+{
+	u32 int_shadow = kvm_x86_ops->get_interrupt_shadow(ctxt->vcpu, mask);
+	/*
+	 * an sti; sti; sequence only disable interrupts for the first
+	 * instruction. So, if the last instruction, be it emulated or
+	 * not, left the system with the INT_STI flag enabled, it
+	 * 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))
+		ctxt->interruptibility = mask;
+}
+
 int
 x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
@@ -1372,6 +1386,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 	int io_dir_in;
 	int rc = 0;
 
+	ctxt->interruptibility = 0;
+
 	/* Shadow copy of register state. Committed on successful emulation.
 	 * NOTE: we can copy them from vcpu as x86_decode_insn() doesn't
 	 * modify them.
@@ -1618,6 +1634,9 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 		int err;
 
 		sel = c->src.val;
+		if (c->modrm_reg == VCPU_SREG_SS)
+			toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS);
+
 		if (c->modrm_reg <= 5) {
 			type_bits = (c->modrm_reg == 1) ? 9 : 1;
 			err = kvm_load_segment_descriptor(ctxt->vcpu, sel,
@@ -1847,6 +1866,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 		c->dst.type = OP_NONE;	/* Disable writeback. */
 		break;
 	case 0xfb: /* sti */
+		toggle_interruptibility(ctxt, X86_SHADOW_INT_STI);
 		ctxt->eflags |= X86_EFLAGS_IF;
 		c->dst.type = OP_NONE;	/* Disable writeback. */
 		break;