From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH 2/2] x86: Bail out on unemulated instructions Date: Sun, 15 Aug 2010 15:49:00 +0300 Message-ID: <20100815124900.GS10499@redhat.com> References: <1281801094-4515-1-git-send-email-m.gamal005@gmail.com> <1281801094-4515-2-git-send-email-m.gamal005@gmail.com> <20100815073236.GP10499@redhat.com> <20100815124112.GR10499@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi@redhat.com, mtosatti@redhat.com, kvm@vger.kernel.org To: Mohammed Gamal Return-path: Received: from mx1.redhat.com ([209.132.183.28]:64574 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758417Ab0HOQMF (ORCPT ); Sun, 15 Aug 2010 12:12:05 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Aug 15, 2010 at 03:43:15PM +0300, Mohammed Gamal wrote: > 2010/8/15 Gleb Natapov : > > On Sun, Aug 15, 2010 at 03:40:00PM +0300, Mohammed Gamal wrote: > >> On Sun, Aug 15, 2010 at 10:32 AM, Gleb Natapov wrote: > >> > On Sat, Aug 14, 2010 at 06:51:34PM +0300, Mohammed Gamal wrote: > >> >> If emulation fails due to the instruction being unemulated. Return immediately > >> >> instead of restarting the instruction and infinitely trying to execute it. > >> >> > >> > This is already handled correctly as far as I can see. Sometimes > >> > instruction should be retried and reexecute_instruction() checks > >> > for that case. If instruction emulation fails in big real mode > >> > re-executing instruction will be useless though, so what should be done > >> > is to make reexecute_instruction() return false if vcpu is in big real > >> > mode and cpu relies on emulation to handle it. > >> We don't have a separate mode for big real mode. The emulation modes > >> we have are real and vm86 > >> > > That doesn't makes the patch right. So we will have to figure something > > out. > True. Can we do it for real mode in general (i.e. X86EMUL_MODE_REAL)? If we flush all shadow pages when moving from paged mode to non paged checking for X86EMUL_MODE_REAL sounds enough to me, but Avi knows better. Or we can add is_big_real_mode() callback to x86_ops and implement it in vmx accordingly. -- Gleb.