From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1768274AbcHRObS (ORCPT ); Thu, 18 Aug 2016 10:31:18 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37443 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1950490AbcHROPi (ORCPT ); Thu, 18 Aug 2016 10:15:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , dri-devel@lists.freedesktop.org, Akash Goel , Imre Deak , Daniel Vetter , Jason Ekstrand , Mika Kuoppala Subject: [PATCH 4.7 132/186] drm: Restore double clflush on the last partial cacheline Date: Thu, 18 Aug 2016 15:59:09 +0200 Message-Id: <20160818135937.901515407@linuxfoundation.org> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160818135932.219369981@linuxfoundation.org> References: <20160818135932.219369981@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson commit 396f5d62d1a5fd99421855a08ffdef8edb43c76e upstream. This effectively reverts commit afcd950cafea6e27b739fe7772cbbeed37d05b8b Author: Chris Wilson Date: Wed Jun 10 15:58:01 2015 +0100 drm: Avoid the double clflush on the last cache line in drm_clflush_virt_range() as we have observed issues with serialisation of the clflush operations on Baytrail+ Atoms with partial updates. Applying the double flush on the last cacheline forces that clflush to be ordered with respect to the previous clflush, and the mfence then protects against prefetches crossing the clflush boundary. The same issue can be demonstrated in userspace with igt/gem_exec_flush. Fixes: afcd950cafea6 (drm: Avoid the double clflush on the last cache...) Testcase: igt/gem_concurrent_blit Testcase: igt/gem_partial_pread_pwrite Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92845 Signed-off-by: Chris Wilson Cc: dri-devel@lists.freedesktop.org Cc: Akash Goel Cc: Imre Deak Cc: Daniel Vetter Cc: Jason Ekstrand Reviewed-by: Mika Kuoppala Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1467880930-23082-6-git-send-email-chris@chris-wilson.co.uk Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_cache.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/gpu/drm/drm_cache.c +++ b/drivers/gpu/drm/drm_cache.c @@ -136,6 +136,7 @@ drm_clflush_virt_range(void *addr, unsig mb(); for (; addr < end; addr += size) clflushopt(addr); + clflushopt(end - 1); /* force serialisation */ mb(); return; }