From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754597Ab0D0Jbe (ORCPT ); Tue, 27 Apr 2010 05:31:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9876 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754340Ab0D0Jbc (ORCPT ); Tue, 27 Apr 2010 05:31:32 -0400 Message-ID: <4BD6AEC7.5020609@redhat.com> Date: Tue, 27 Apr 2010 12:30:47 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Huang Ying CC: "linux-kernel@vger.kernel.org" , Andi Kleen , Andrew Morton , "masbock@linux.vnet.ibm.com" , kvm@vger.kernel.org Subject: Re: [PATCH 2/2] KVM, Fix QEMU-KVM is killed by guest SRAO MCE References: <1272351860.24125.15.camel@yhuang-dev.sh.intel.com> <4BD69680.10402@redhat.com> <1272360341.24125.116.camel@yhuang-dev.sh.intel.com> In-Reply-To: <1272360341.24125.116.camel@yhuang-dev.sh.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/27/2010 12:25 PM, Huang Ying wrote: > > >> On 04/27/2010 10:04 AM, Huang Ying wrote: >> >>> +static void kvm_send_hwpoison_signal(struct kvm *kvm, gfn_t gfn) >>> +{ >>> + char buf[1]; >>> + void __user *hva; >>> + int r; >>> + >>> + /* Touch the page, so send SIGBUS */ >>> + hva = (void __user *)gfn_to_hva(kvm, gfn); >>> + r = copy_from_user(buf, hva, 1); >>> >>> >> No error check? What will a copy_from_user() of poisoned page expected >> to return? >> >> Best to return -EFAULT on failure for consistency. >> > Just want to use the side effect of copy_from_user, SIGBUS will be sent > to current process because the page touched is marked as poisoned. That > is, failure is expected, so the return value is not checked. > What if the failure doesn't happen? Say, someone mmap()ed over the page. btw, better to use (void)copy_from_user(...) instead to avoid the initialized but not used warning the compiler may generate. -- error compiling committee.c: too many arguments to function