On 01/07/2012 12:37 PM, Stefan Hajnoczi wrote:
> The unimplemented movdqa (66 0f 7f 07) instruction triggers a bug in
> the x86 emulator. The emulator should fail since the instruction is
> unimplemented. However the emulator thinks it is succeeding but we
> keep re-executing the same instruction over and over. top shows 100%
> CPU utilization and perf top shows we're constantly running through
> the x86 emulator in kvm.ko.
>
> The problem is that ctxt->d != 0 even though the instruction is
> unimplemented (N):
>
> while (ctxt->d & GroupMask) {
> switch (ctxt->d & GroupMask) {
> ... <-- opcode zeroed if instruction is unimplemented
> }
>
> ctxt->d &= ~(u64)GroupMask; <-- only clears GroupMask
> ctxt->d |= opcode.flags; <-- opcode.flags == 0, ctxt->d != 0
> }
>
> ...
>
> /* Unrecognised? */
> if (ctxt->d == 0 || (ctxt->d & Undefined)) <-- always false
> return EMULATION_FAILED;
>
#define N D(Undefined)
should fix it.
--
error compiling committee.c: too many arguments to function
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