From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: Xen 4.3 development update RC2 imminent Date: Tue, 21 May 2013 17:13:09 +0100 Message-ID: <519B9D15.7060004@eu.citrix.com> References: <519B7F67.2050602@citrix.com> <519B8541.8090505@citrix.com> <519BA6F302000078000D7CF2@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <519BA6F302000078000D7CF2@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Anthony PERARD , Andrew Cooper , Fabio Fantoni , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 05/21/2013 03:55 PM, Jan Beulich wrote: >>>> On 21.05.13 at 16:31, Andrew Cooper wrote: >> On 21/05/13 15:06, Anthony PERARD wrote: >>> But then, once this applied, qxl is still not able to start. Xorg crash >>> (in the guest), and here is why: >>> >>> (XEN) emulate.c:88:d18 bad mmio size 16 >>> (XEN) io.c:201:d18 MMIO emulation failed @ 0033:7fd2de390430: f3 0f 6f >>> 19 41 83 e8 403 >>> (XEN) emulate.c:88:d18 bad mmio size 16 >>> (XEN) io.c:201:d18 MMIO emulation failed @ 0033:7fd2de390430: f3 0f 6f >>> 19 41 83 e8 403 >> >> Disassembly of section .data: >> >> 0000000000000000 <.data>: >> 0: f3 0f 6f 19 movdqu (%rcx),%xmm3 >> >> Xen does not support emulating SSE instructions. We have sporadically >> seen similar errors from Windows guests. The best guess I have managed >> to get so far is that %rcx is a pointer to something which Xen thinks is >> an MMIO page. >> >> In this case, it looks like X is copying from MMIO into an xmm register, >> scraping the framebuffer perhaps? In the windows failure, it was the >> pagescrub trying to zero ram, which clearly indicated something wonky in >> the combined idea of the memory map. >> >> If Spice is doing something valid and sensible, then Xen will likely >> need extending to be able to emulate SSE instructions. > > The emulator in the hypervisor can handle simple SSE instructions > like the above quite well. It's not immediately clear to me why > hvmemul_do_io() would need to limit the size to no more than a > long's width. Perhaps the data passing to the device model may > need adjustment to accommodate wider entities... Hmm, but the code seems to indicate that the DM can handle wider entities, by "reading all ones": if ( dir == IOREQ_READ ) memset(p_data, ~0, size); Anthony, do you want to try making that size check one size bigger (e.g., allow it to be 16 or 32)? I'd send you a patch but it's got to be easier to just change than to apply the patch... -George