From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934113Ab2AKWLo (ORCPT ); Wed, 11 Jan 2012 17:11:44 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:51318 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933993Ab2AKWLn (ORCPT ); Wed, 11 Jan 2012 17:11:43 -0500 Date: Thu, 12 Jan 2012 07:11:37 +0900 From: Takuya Yoshikawa To: Nadav Amit Cc: Avi Kivity , Marcelo Tosatti , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Nadav Amit Subject: Re: [PATCH 1/2] KVM: Exception during emulation decode should propagate Message-Id: <20120112071137.303628cea69b79868956d860@gmail.com> In-Reply-To: <1326300811-17065-1-git-send-email-namit@cs.technion.ac.il> References: <1326300811-17065-1-git-send-email-namit@cs.technion.ac.il> X-Mailer: Sylpheed 3.2.0beta3 (GTK+ 2.24.6; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 11 Jan 2012 18:53:30 +0200 Nadav Amit wrote: > An exception might occur during decode (e.g., #PF during fetch). > Currently, the exception is ignored and emulation is performed. When I cleaned up insn_fetch(), I thought that fetching the instruction which is being executed by the guest cannot cause #PF. The possibility that a meaningless userspace might similtaneously unmap the page, noted by Avi IIRC, was ignored intentionally, so we just fail in such a case. Did you see any real problem? Takuya > Instead, emulation should be skipped and the fault should be injected. > Skipping instruction should report a failure in this case.