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 17:16:57 +0100 Message-ID: <519B9DF9.7090303@eu.citrix.com> References: <519B7F67.2050602@citrix.com> <519B8541.8090505@citrix.com> <519BA6F302000078000D7CF2@nat28.tlf.novell.com> <519B9D15.7060004@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <519B9D15.7060004@eu.citrix.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 05:13 PM, George Dunlap wrote: > 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)? No, that obviously won't work, because of the line just following: if ( (p_data != NULL) && (dir == IOREQ_WRITE) ) { memcpy(&value, p_data, size); p_data = NULL; } value is of size "long", so this won't work. -George