On Tue, Aug 17, 2010 at 12:20:34PM +0300, Avi Kivity wrote:
> On 08/17/2010 12:13 PM, Gleb Natapov wrote:
> >On Tue, Aug 17, 2010 at 11:26:43AM +0300, Avi Kivity wrote:
> >>EFLAGS.ZF needs to be checked after each iteration, not before.
> >>
> >>Signed-off-by: Avi Kivity<[email protected]>
> >>---
> >> arch/x86/kvm/emulate.c | 42 +++++++++++++++++++++++-------------------
> >> 1 files changed, 23 insertions(+), 19 deletions(-)
> >>
> >>diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> >>index 0c0ada9..a2edfb1 100644
> >>--- a/arch/x86/kvm/emulate.c
> >>+++ b/arch/x86/kvm/emulate.c
> >>@@ -2747,6 +2747,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
> >> int rc = X86EMUL_CONTINUE;
> >> int saved_dst_type = c->dst.type;
> >> int irq; /* Used for int 3, int, and into */
> >>+ ulong old_eip;
> >Is never used.
> >
>
> Whoops.
>
> >>@@ -3250,13 +3234,33 @@ writeback:
> >> if (c->rep_prefix&& (c->d& String)) {
> >> struct read_cache *rc =&ctxt->decode.io_read;
> >> register_address_increment(c,&c->regs[VCPU_REGS_RCX], -1);
> >>+ /* The second termination condition only applies for REPE
> >>+ * and REPNE. Test if the repeat string operation prefix is
> >>+ * REPE/REPZ or REPNE/REPNZ and if it's the case it tests the
> >>+ * corresponding termination condition according to:
> >>+ * - if REPE/REPZ and ZF = 0 then done
> >>+ * - if REPNE/REPNZ and ZF = 1 then done
> >>+ */
> >>+ if ((c->b == 0xa6) || (c->b == 0xa7) ||
> >>+ (c->b == 0xae) || (c->b == 0xaf)) {
> >>+ trace_printk("c->eip %lx ctxt->eip %lx\n",
> >>+ c->eip, ctxt->eip);
> >>+ if (((c->rep_prefix == REPE_PREFIX)&&
> >>+ ((ctxt->eflags& EFLG_ZF) == 0))
> >>+ || ((c->rep_prefix == REPNE_PREFIX)&&
> >>+ ((ctxt->eflags& EFLG_ZF) == EFLG_ZF))) {
> >>+ ctxt->restart = false;
> >Why not jump to string_done label here?
>
> It does a 'goto done;' which skips a couple of things.
>
The only thing it skips is:
ctxt->decode.mem_read.end = 0;
as far as I can see. And this is ok if instruction is completed.
> >>+ }
> >>+ }
> >> /*
> >> * Re-enter guest when pio read ahead buffer is empty or,
> >> * if it is not used, after each 1024 iteration.
> >> */
> >> if ((rc->end == 0&& !(c->regs[VCPU_REGS_RCX]& 0x3ff)) ||
> >>- (rc->end != 0&& rc->end == rc->pos))
> >>+ (rc->end != 0&& rc->end == rc->pos)) {
> >> ctxt->restart = false;
> >>+ c->eip = ctxt->eip;
> >We can get here when instruction is completed by above "if", so same
> >instruction will reexecute once again.
>
> Not good. Will redo (and write tests).
>
>
> --
> error compiling committee.c: too many arguments to function
--
Gleb.
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