Commit e6e39f04 authored Apr 18, 2014 by Nadav Amit Committed by Marcelo Tosatti Apr 23, 2014

KVM: x86: IN instruction emulation should ignore REP-prefix

The IN instruction is not be affected by REP-prefix as INS is. Therefore, the
emulation should ignore the REP prefix as well. The current emulator
implementation tries to perform writeback when IN instruction with REP-prefix
is emulated. This causes it to perform wrong memory write or spurious #GP
exception to be injected to the guest.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent 346874c9

arch/x86/kvm/emulate.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1324,7 +1324,8 @@ static int pio_in_emulated(struct x86_emulate_ctxt *ctxt,
		rc->end = n * size;
		}

		if (ctxt->rep_prefix && !(ctxt->eflags & EFLG_DF)) {
		if (ctxt->rep_prefix && (ctxt->d & String) &&
		!(ctxt->eflags & EFLG_DF)) {
		ctxt->dst.data = rc->data + rc->pos;
		ctxt->dst.type = OP_MEM_STR;
		ctxt->dst.count = (rc->end - rc->pos) / size;