From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NcfUL-0000Uv-KY for qemu-devel@nongnu.org; Wed, 03 Feb 2010 08:41:49 -0500 Received: from [199.232.76.173] (port=59335 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NcfUL-0000Uj-4M for qemu-devel@nongnu.org; Wed, 03 Feb 2010 08:41:49 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1NcfUI-0000A9-Ov for qemu-devel@nongnu.org; Wed, 03 Feb 2010 08:41:48 -0500 Received: from e5.ny.us.ibm.com ([32.97.182.145]:40156) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NcfUI-00008T-C2 for qemu-devel@nongnu.org; Wed, 03 Feb 2010 08:41:46 -0500 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by e5.ny.us.ibm.com (8.14.3/8.13.1) with ESMTP id o13DSWcA005366 for ; Wed, 3 Feb 2010 08:28:32 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o13DfXmA128738 for ; Wed, 3 Feb 2010 08:41:33 -0500 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o13DfQOK032148 for ; Wed, 3 Feb 2010 06:41:27 -0700 Message-ID: <4B697D04.7070507@linux.vnet.ibm.com> Date: Wed, 03 Feb 2010 07:41:24 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [Patch] Support translating Guest physical address to Host virtual address. References: <4B60B28A.40400@linux.vnet.ibm.com> <1264631460.29051.35.camel@w-amax.beaverton.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Zheng, Jiajia" Cc: "lmr@redhat.com" , "Li, Haicheng" , Max Asbock , "qemu-devel@nongnu.org" , "You, Yongkang" , "avi@redhat.com" , "Kleen, Andi" On 02/02/2010 10:04 PM, Zheng, Jiajia wrote: > Hi, > Any futher comments for this patch so that we can modify? > Unfortunately, I see no way to modify this feature so that it would be acceptable to upstream. I think you're going to have to carry this patch for your own debugging. The problem is, the approach you're taking to testing is extremely racy. Even just with the p2v command, the mapping within qemu that translates guest physical to host virtual is not stable over any given period of time. By the time the monitor prints out the virtual mapping of a host page, it's already potentially wrong. Likewise, the virtual->physical mapping within the host is also not stable so using that virtual address to lookup a physical address in the kernel is inherently racy. If you want to integrate MCE testing into qemu using the host to inject MCEs, you'll need to figure out a way to do it that allows the whole thing to be done without potentially killing the wrong process or injecting it to within the wrong address within qemu. I suspect that's going to be very difficult to achieve. Regards, Anthony Liguori