KVM: Deal with interrupt shadow state for emulated instructions

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kvm / x86_emulate.c

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index d2664fcba7fafaed26b43bf59912039ce85afddc..c1b6c232e02b180287e7b0e91a41ddb34c699689 100644 (file)
--- a/arch/x86/kvm/x86_emulate.c
+++ b/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 @@ special_insn:
                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 @@ special_insn:
                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;