KVM: x86 emulator: Add into, int, and int3 instructions (opcodes 0xcc-0xce)

This adds support for int instructions to the emulator.

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a9a4a0b78a7d..5205d6890828 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1180,6 +1180,67 @@ static int emulate_popa(struct x86_emulate_ctxt *ctxt,
         return rc;
 }
 
+int emulate_int_real(struct x86_emulate_ctxt *ctxt,
+                               struct x86_emulate_ops *ops, int irq)
+{
+        struct decode_cache *c = &ctxt->decode;
+        int rc = X86EMUL_CONTINUE;
+        struct desc_ptr dt;
+        gva_t cs_addr;
+        gva_t eip_addr;
+        u16 cs, eip;
+        u32 err;
+
+        /* TODO: Add limit checks */
+        c->src.val = ctxt->eflags;
+        emulate_push(ctxt, ops);
+
+        ctxt->eflags &= ~(EFLG_IF | EFLG_TF | EFLG_AC);
+
+        c->src.val = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
+        emulate_push(ctxt, ops);
+
+        c->src.val = c->eip;
+        emulate_push(ctxt, ops);
+
+        ops->get_idt(&dt, ctxt->vcpu);
+
+        eip_addr = dt.address + (irq << 2);
+        cs_addr = dt.address + (irq << 2) + 2;
+
+        rc = ops->read_std(cs_addr, &cs, 2, ctxt->vcpu, &err);
+        if (rc != X86EMUL_CONTINUE)
+                return rc;
+
+        rc = ops->read_std(eip_addr, &eip, 2, ctxt->vcpu, &err);
+        if (rc != X86EMUL_CONTINUE)
+                return rc;
+
+        rc = load_segment_descriptor(ctxt, ops, cs, VCPU_SREG_CS);
+        if (rc != X86EMUL_CONTINUE)
+                return rc;
+
+        c->eip = eip;
+
+        return rc;
+}
+
+static int emulate_int(struct x86_emulate_ctxt *ctxt,
+                       struct x86_emulate_ops *ops, int irq)
+{
+        switch(ctxt->mode) {
+        case X86EMUL_MODE_REAL:
+                return emulate_int_real(ctxt, ops, irq);
+        case X86EMUL_MODE_VM86:
+        case X86EMUL_MODE_PROT16:
+        case X86EMUL_MODE_PROT32:
+        case X86EMUL_MODE_PROT64:
+        default:
+                /* Protected mode interrupts unimplemented yet */
+                return X86EMUL_UNHANDLEABLE;
+        }
+}
+
 static int emulate_iret_real(struct x86_emulate_ctxt *ctxt,
                              struct x86_emulate_ops *ops)
 {
@@ -2616,6 +2677,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
         struct decode_cache *c = &ctxt->decode;
         int rc = X86EMUL_CONTINUE;
         int saved_dst_type = c->dst.type;
+        int irq; /* Used for int 3, int, and into */
 
         ctxt->decode.mem_read.pos = 0;
 
@@ -2960,6 +3022,22 @@ special_insn:
                 if (rc != X86EMUL_CONTINUE)
                         goto done;
                 break;
+        case 0xcc:              /* int3 */
+                irq = 3;
+                goto do_interrupt;
+        case 0xcd:              /* int n */
+                irq = c->src.val;
+        do_interrupt:
+                rc = emulate_int(ctxt, ops, irq);
+                if (rc != X86EMUL_CONTINUE)
+                        goto done;
+                break;
+        case 0xce:              /* into */
+                if (ctxt->eflags & EFLG_OF) {
+                        irq = 4;
+                        goto do_interrupt;
+                }
+                break;
         case 0xcf:              /* iret */
                 rc = emulate_iret(ctxt, ops);