KVM: x86 emulator: get rid of "restart" in emulation context.

[pandora-kernel.git] / arch / x86 / kvm / emulate.c

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3dcbc1d..ec35a71 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -437,7 +437,6 @@ static void emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,
        ctxt->exception = vec;
        ctxt->error_code = error;
        ctxt->error_code_valid = valid;
-       ctxt->restart = false;
 }
 
 static void emulate_gp(struct x86_emulate_ctxt *ctxt, int err)
@@ -2633,9 +2632,6 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt)
        struct opcode opcode, *g_mod012, *g_mod3;
        struct operand memop = { .type = OP_NONE };
 
-       /* we cannot decode insn before we complete previous rep insn */
-       WARN_ON(ctxt->restart);
-
        c->eip = ctxt->eip;
        c->fetch.start = c->fetch.end = c->eip;
        ctxt->cs_base = seg_base(ctxt, ops, VCPU_SREG_CS);
@@ -2985,10 +2981,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
        }
 
        if (c->rep_prefix && (c->d & String)) {
-               ctxt->restart = true;
                /* All REP prefixes have the same first termination condition */
                if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0) {
-                       ctxt->restart = false;
                        ctxt->eip = c->eip;
                        goto done;
                }
@@ -3446,28 +3440,29 @@ writeback:
                struct read_cache *r = &ctxt->decode.io_read;
                register_address_increment(c, &c->regs[VCPU_REGS_RCX], -1);
 
-               if (string_insn_completed(ctxt))
-                       ctxt->restart = false;
-               /*
-                * Re-enter guest when pio read ahead buffer is empty or,
-                * if it is not used, after each 1024 iteration.
-                */
-               else if ((r->end == 0 && !(c->regs[VCPU_REGS_RCX] & 0x3ff)) ||
-                        (r->end != 0 && r->end == r->pos)) {
-                       ctxt->restart = false;
-                       c->eip = ctxt->eip;
+               if (!string_insn_completed(ctxt)) {
+                       /*
+                        * Re-enter guest when pio read ahead buffer is empty
+                        * or, if it is not used, after each 1024 iteration.
+                        */
+                       if ((r->end != 0 || c->regs[VCPU_REGS_RCX] & 0x3ff) &&
+                           (r->end == 0 || r->end != r->pos)) {
+                               /*
+                                * Reset read cache. Usually happens before
+                                * decode, but since instruction is restarted
+                                * we have to do it here.
+                                */
+                               ctxt->decode.mem_read.end = 0;
+                               return EMULATION_RESTART;
+                       }
+                       goto done; /* skip rip writeback */
                }
        }
-       /*
-        * reset read cache here in case string instruction is restared
-        * without decoding
-        */
-       ctxt->decode.mem_read.end = 0;
-       if (!ctxt->restart)
-               ctxt->eip = c->eip;
+
+       ctxt->eip = c->eip;
 
 done:
-       return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
+       return (rc == X86EMUL_UNHANDLEABLE) ? EMULATION_FAILED : EMULATION_OK;
 
 twobyte_insn:
        switch (c->b) {