From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: Test if on newer xen all SSE2 and SSE3 instructions are effectively working Date: Thu, 21 Nov 2013 15:38:57 +0000 Message-ID: <528E2911.1040002@citrix.com> References: <528DE5D7.60701@m2r.biz> <528E251E.1020907@citrix.com> <528E278D.4020102@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <528E278D.4020102@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: George Dunlap Cc: "Nakajima, Jun" , Fabio Fantoni , "Dong, Eddie" , xen-devel , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 21/11/13 15:32, George Dunlap wrote: > On 21/11/13 15:22, Andrew Cooper wrote: >> On 21/11/13 15:12, George Dunlap wrote: >>> On Thu, Nov 21, 2013 at 10:52 AM, Fabio Fantoni >>> wrote: >>>> I'm trying to test if on newer xen all SSE2 and SSE3 instructions are >>>> effectively working. >>>> I tried this simple program to test SSE2: >>>> http://forum.nasm.us/index.php?topic=1605.0 >>>> But probably use only instructions with short operand because SSE2 >>>> on this >>>> program is working also on old xen 4.0 where Jan Beulich patches to >>>> support >>>> long operands are missing. >>>> Are there any minimal program to test if SSE instructions with MMIO >>>> operands >>>>> 8 byte are working? >>> I don't see the code there doing MMIO -- it's just doing operations on >>> normal RAM, which is not emulated by Xen at all, but executed natively >>> by the processor. >>> >>> What you need is a program that will do this to an MMIO region -- that >>> will be a much trickier thing to set up, I think. >>> >>> -George >> The problem with SSE is only when the guest performs an SSE (or larger) >> operation on a piece of memory which ends up being emulated and handed >> to qemu. The ioreq protocol doesn't have a way of signalling an operand >> width greater than 64 bits. > > I'd like to emphasize the "and" in the first sentence. You might be > able to trigger a Xen emulation in any number of ways (disabling HAP > and then doing an SSE instruction on an in-use PT might do it). But > Xen allegedly already does the actual emulation correctly -- as Andy > said, it's only the path to qemu that wasn't working before. > > -George > Oops yes - I should have emphasised that a bit more. I believe Jan submitted a hacked-fix for the qemu path which fixes the immediate issue (for 128bit emulation) but is in need of a redesign for wider emulation; 256bit is available with AVX, and 512bit is on its way with AVX2. As for testing individual instructions, there is tools/tests/x86_emulator/test_x86_emulator.c which tests a token few instructions against Xen's emulation code, but it is far from comprehensive. ~Andrew