From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takuya Yoshikawa Subject: Re: [PATCH 22/24] KVM: x86 emulator: restart string instruction without going back to a guest. Date: Wed, 10 Mar 2010 19:08:31 +0900 Message-ID: <4B976F9F.7090804@oss.ntt.co.jp> References: <1268143762-4000-1-git-send-email-gleb@redhat.com> <1268143762-4000-23-git-send-email-gleb@redhat.com> <4B966035.2050904@redhat.com> <20100309181157.GF9066@redhat.com> <4B97043C.2000603@oss.ntt.co.jp> <20100310090633.GS16909@redhat.com> <4B976282.7020108@oss.ntt.co.jp> <20100310091508.GT16909@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Avi Kivity , kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from serv2.oss.ntt.co.jp ([222.151.198.100]:39122 "EHLO serv2.oss.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932114Ab0CJKF7 (ORCPT ); Wed, 10 Mar 2010 05:05:59 -0500 In-Reply-To: <20100310091508.GT16909@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Gleb Natapov wrote: >>>> >>> Entering guest from time to time will not change semantics of the >>> processor (if code is not modified under processor's feet at least). >>> Currently we reenter guest mode after each iteration of string >>> instruction for all instruction but ins/outs. >>> >> E.g., is there no chance that during the repetitions, in the middle of the >> repetitions, page faults occur? If it can, without entering the guest, can >> we handle it? >> -- I lack some basic assumptions? >> > If page fault occurs we inject it to the guest. > Oh, I maight fail to tell what I worried about. Opposite, I mean, I worried about NOT reentering the guest case. I know that current implementation with reentrance is OK. To inject a page fault without reentering the guest, we need to add some more hacks to the emulator IIUC. Thanks, Takuya