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>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a9a4a0b..5205d68 100644 (file)
--- 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);