From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751488AbdBBMLe (ORCPT ); Thu, 2 Feb 2017 07:11:34 -0500 Received: from mga03.intel.com ([134.134.136.65]:46143 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970AbdBBMLd (ORCPT ); Thu, 2 Feb 2017 07:11:33 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,324,1477983600"; d="scan'208";a="1121144996" Subject: Re: [Intel-gfx] [PATCH] drm/i915: fix i915 running as dom0 under Xen To: Juergen Gross , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org References: <20170202094711.939-1-jgross@suse.com> Cc: airlied@linux.ie, daniel.vetter@intel.com, konrad.wilk@oracle.com From: Tvrtko Ursulin Message-ID: <23599992-d008-af02-493d-9c2d207f39af@linux.intel.com> Date: Thu, 2 Feb 2017 12:11:29 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170202094711.939-1-jgross@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/02/2017 09:47, Juergen Gross wrote: > Commit 920cf4194954ec ("drm/i915: Introduce an internal allocator for > disposable private objects") introduced a regression for the kernel > running as Xen dom0: when switching to graphics mode a GPU HANG > occurred. > > Reason seems to be a missing adaption similar to that done in > commit 7453c549f5f648 ("swiotlb: Export swiotlb_max_segment to users") > to i915_gem_object_get_pages_internal(). > > So limit the maximum page order to be used according to the maximum > swiotlb segment size instead to the complete swiotlb size. > > Signed-off-by: Juergen Gross > --- > Please consider for 4.10 as otherwise 4.10 will be unusable as Xen dom0 > with i915 graphics. > --- > drivers/gpu/drm/i915/i915_gem_internal.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_internal.c b/drivers/gpu/drm/i915/i915_gem_internal.c > index 4b3ff3e..d09c749 100644 > --- a/drivers/gpu/drm/i915/i915_gem_internal.c > +++ b/drivers/gpu/drm/i915/i915_gem_internal.c > @@ -66,8 +66,16 @@ i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) > > max_order = MAX_ORDER; > #ifdef CONFIG_SWIOTLB > - if (swiotlb_nr_tbl()) /* minimum max swiotlb size is IO_TLB_SEGSIZE */ > - max_order = min(max_order, ilog2(IO_TLB_SEGPAGES)); > + if (swiotlb_nr_tbl()) { > + unsigned int max_segment; > + > + max_segment = swiotlb_max_segment(); > + if (max_segment) { > + max_segment = max_t(unsigned int, max_segment, > + PAGE_SIZE) >> PAGE_SHIFT; > + max_order = min(max_order, ilog2(max_segment)); > + } > + } > #endif > > gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE; > Looks OK to me. We could bikeshed it to only use swiotlb_max_segment() which I think was the intention when that API was added but can leave that for the future. Reviewed-by: Tvrtko Ursulin Regards, Tvrtko