From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joonas Lahtinen Subject: Re: [PATCH V6] drm/i915: Disable stolen memory when i915 runs in guest vm Date: Fri, 05 May 2017 12:21:12 +0300 Message-ID: <1493976072.3551.19.camel@linux.intel.com> References: <1493116501-29327-1-git-send-email-xiong.y.zhang@intel.com> <1493122003.3731.27.camel@linux.intel.com> <8082FF9BCB2B054996454E47167FF4EC1C4D0CAA@SHSMSX104.ccr.corp.intel.com> <8082FF9BCB2B054996454E47167FF4EC1C4D77EC@SHSMSX104.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <8082FF9BCB2B054996454E47167FF4EC1C4D77EC@SHSMSX104.ccr.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: "Zhang, Xiong Y" , "Tian, Kevin" , "Vetter, Daniel" , "zhenyuw@linux.intel.com" , "jani.nikula@linux.intel.com" , "alex.williamson@redhat.com" , David Woodhouse , "Bloomfield, Jon" Cc: "intel-gfx@lists.freedesktop.org" , "intel-gvt-dev@lists.freedesktop.org" , "stable@vger.kernel.org" List-Id: intel-gfx@lists.freedesktop.org T24ga2UsIDIwMTctMDUtMDMgYXQgMDk6MjIgKzAwMDAsIFpoYW5nLCBYaW9uZyBZIHdyb3RlOgo+ ID4gCj4gPiA+IAo+ID4gPiArIERhdmlkIGFuZCBKb24KPiA+ID4gCj4gPiA+IE9uIHRpLCAyMDE3 LTA0LTI1IGF0IDE4OjM0ICswODAwLCBYaW9uZyBaaGFuZyB3cm90ZToKPiA+ID4gCj4gPiA+IFRo ZSBibG9ja2luZyBpc3N1ZSBJIHNlZSBpcyB0aGF0IGJpc2VjdGluZyBpcyBzdGlsbCBub3QgcG9p bnRpbmcgYXQKPiA+ID4gcmVsZXZhbnQgY29tbWl0cy4gQm90aCBiaXNlY3RlZCBjb21taXRzIGZy b20gQnVnemlsbGEgYXJlIG5vdCByZWxhdGVkCj4gPiA+IHRvIGNoYW5nZXMgaW4gc3RvbGVuIG1l bW9yeSB1c2FnZSBiZWhhdmlvci4gSSdkIGFzc3VtZSBhIHN1Y2Nlc3NmdWwKPiA+ID4gYmlzZWN0 IHRvIGxhbmQgYXQgdGhlIHBhdGNoZXMgd2hlcmUgd2Ugc3RhcnQgY3JlYXRpbmcga2VybmVsIGlu dGVybmFsCj4gPiA+IG9iamVjdHMgZnJvbSBzdG9sZW4gbWVtb3J5LiBPdGhlcndpc2Ugd2UgY291 bGQgYmUgaWdub3JpbmcgYSBidWcKPiA+ID4gZWxzZXdoZXJlLiBJZiBpdCBjb25zaXN0ZW50bHkg 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CldoaWxlIGRvaW5nIHRoYXQsIHBsZWFzZSB1cGRhdGUgdGhlIGZyZWVkZXNrdG9wLm9yZyBidWdz LgoKUmVnYXJkcywgSm9vbmFzCi0tIApKb29uYXMgTGFodGluZW4KT3BlbiBTb3VyY2UgVGVjaG5v bG9neSBDZW50ZXIKSW50ZWwgQ29ycG9yYXRpb24KX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX18KSW50ZWwtZ2Z4IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlz dHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4v bGlzdGluZm8vaW50ZWwtZ2Z4Cg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com ([192.55.52.93]:34467 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752281AbdEEJVR (ORCPT ); Fri, 5 May 2017 05:21:17 -0400 Message-ID: <1493976072.3551.19.camel@linux.intel.com> Subject: Re: [PATCH V6] drm/i915: Disable stolen memory when i915 runs in guest vm From: Joonas Lahtinen To: "Zhang, Xiong Y" , "Tian, Kevin" , "Vetter, Daniel" , "zhenyuw@linux.intel.com" , "jani.nikula@linux.intel.com" , "alex.williamson@redhat.com" , David Woodhouse , "Bloomfield, Jon" Cc: "intel-gfx@lists.freedesktop.org" , "intel-gvt-dev@lists.freedesktop.org" , "stable@vger.kernel.org" Date: Fri, 05 May 2017 12:21:12 +0300 In-Reply-To: <8082FF9BCB2B054996454E47167FF4EC1C4D77EC@SHSMSX104.ccr.corp.intel.com> References: <1493116501-29327-1-git-send-email-xiong.y.zhang@intel.com> <1493122003.3731.27.camel@linux.intel.com> <8082FF9BCB2B054996454E47167FF4EC1C4D0CAA@SHSMSX104.ccr.corp.intel.com> <8082FF9BCB2B054996454E47167FF4EC1C4D77EC@SHSMSX104.ccr.corp.intel.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: On ke, 2017-05-03 at 09:22 +0000, Zhang, Xiong Y wrote: > > > > > > > > + David and Jon > > > > > > On ti, 2017-04-25 at 18:34 +0800, Xiong Zhang wrote: > > > > > > The blocking issue I see is that bisecting is still not pointing at > > > relevant commits. Both bisected commits from Bugzilla are not related > > > to changes in stolen memory usage behavior. I'd assume a successful > > > bisect to land at the patches where we start creating kernel internal > > > objects from stolen memory. Otherwise we could be ignoring a bug > > > elsewhere. If it consistently lands on those patches, then there might > > > be something wrong with them, in addition to stolen memory problems. > > [Zhang, Xiong Y] I only try kernel 4.8 and 4.9 above, as the bugzilla descripted, > > guest 4.8 kernel doesn't see gpu hang in guest dmesg, 4.9 kernel has gpu hang > > in guest dmesg. From this point, we could do git bisect. > > But tons of IOMMU DMA R/W exception to stolen memory exist in host dmesg > > when guest kernel is 4.8 and 4.9. This means guest domain iommu table > > doesn't > > have mapping for stolen memory and IGD fail in accessing stolen memory > > from guest kernel 4.8 and 4.9. From this point, this issue isn't a regression and > > shouldn't go git bisect. You could check this host error message from the > > bugzilla > > attachment. And this should be fixed first. > > Anyway, I will try my best to get the ideal commit through git bisect, but I'm > > afraid > > the result is the same as past because we don't have a stable good point to > > start git > > bisect. > [Zhang, Xiong Y] hi, Joonas: > As you said, the gpu hang exist because i915 create ring buffer from stolen memory. > I did git bisect again, and the following commit is the first bad commit: > commit c58b735fc762e891481e92af7124b85cb0a51fce > Author: Chris Wilson > Date:   Thu Aug 18 17:16:57 2016 +0100 > >     drm/i915: Allocate rings from stolen > >     If we have stolen available, make use of it for ringbuffer allocation. >     Previously this was restricted to !llc platforms, as writing to stolen >     requires a GGTT mapping - but now that we have partial mappable support, >     the mappable aperture isn't quite so precious so we can use it more >     freely and ringbuffers are a good user for the otherwise wasted stolen. > > After reverting this patch from drm-intel-nightly, I didn't see gpu hang during guest boot process. > So what's our next step ? An appropriate next step would be to evaluate how much work it is to support the RMRR passthrough David mentioned about in his commit. I'd also go talk with the IGD team, why they refuse to load the driver when stolen memory is correctly reported as zero, and insist on being lied to. While doing that, please update the freedesktop.org bugs. Regards, Joonas -- Joonas Lahtinen Open Source Technology Center Intel Corporation