From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MDfRv-000221-N1 for qemu-devel@nongnu.org; Mon, 08 Jun 2009 10:03:43 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MDfRr-0001uU-5B for qemu-devel@nongnu.org; Mon, 08 Jun 2009 10:03:43 -0400 Received: from [199.232.76.173] (port=54153 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDfRq-0001uE-QF for qemu-devel@nongnu.org; Mon, 08 Jun 2009 10:03:38 -0400 Received: from mx2.redhat.com ([66.187.237.31]:34456) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MDfRo-0005PX-Rg for qemu-devel@nongnu.org; Mon, 08 Jun 2009 10:03:37 -0400 Message-ID: <4A2D1A2E.4040407@redhat.com> Date: Mon, 08 Jun 2009 17:03:26 +0300 From: Avi Kivity MIME-Version: 1.0 References: <4A26F1E3.1040509@codemonkey.ws> <4A27FC69.9070501@mayc.ru> <20090605201415.GA22847@csclub.uwaterloo.ca> <20090608001312.GE15426@shareable.org> <4A2CA8C2.2080004@redhat.com> <20090608115755.GD25684@shareable.org> <4A2CFE07.90700@redhat.com> <20090608121626.GF25684@shareable.org> <4A2D03E7.8070702@redhat.com> <4A2D07A3.8090101@siemens.com> <4A2D0CE4.9080405@redhat.com> <4A2D0FB6.20104@siemens.com> <4A2D10FA.2050606@redhat.com> <4A2D15AC.9000004@siemens.com> In-Reply-To: <4A2D15AC.9000004@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: POLL: Why do you use kqemu? List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Anton D Kachalov , "qemu-devel@nongnu.org" , Lennart Sorensen Jan Kiszka wrote: >> When kvm write protects a guest page table in the shadow page table >> entries pointing to that guest page, it should also write protect the >> guest page table in the host page table entries to the same guest page. >> > > Ah, now I got it. What do other hypervisors do? > As far as I can tell, Xen's head is in the sand too. No idea about others. I think qemu/tcg is fine. >>> Does this still apply to nested paging? I guess (hope) not... >>> >>> >> No, nested paging brings cancer and cures world peace. Or something. >> >> > > Well, then it's probably not worth bothering, at least until a real > guest problem is explainable with this limitation. I agree. > Are there any > suspicious reports floating around (maybe not only about Windows)? > Not that I'm aware of. Paging page tables is tricky business. Given that the pointed-to pages may have been evicted while the page table was in swap, I guess a guest would have to revalidate the entries anyway, thus triggering re-shadowing. -- error compiling committee.c: too many arguments to function