From patchwork Thu Jul 18 09:01:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11048671 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C16BB912 for ; Thu, 18 Jul 2019 09:02:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B18FD285D6 for ; Thu, 18 Jul 2019 09:02:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A64F328613; Thu, 18 Jul 2019 09:02:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5DCC028779 for ; Thu, 18 Jul 2019 09:02:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 163316E373; Thu, 18 Jul 2019 09:02:38 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 06D036E373 for ; Thu, 18 Jul 2019 09:02:35 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 17393252-1500050 for multiple; Thu, 18 Jul 2019 10:01:59 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Thu, 18 Jul 2019 10:01:58 +0100 Message-Id: <20190718090158.25123-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.22.0 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915: Flush all user surfaces prior to first use X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Since userspace has the ability to bypass the CPU cache from within its unpriviledged command stream, we have to flush the CPU cache to memory in order to overwrite the previous contents on creation. Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Cc: stablevger.kernel.org --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 25 +++++++---------------- 1 file changed, 7 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index d2a1158868e7..80e02bcdf678 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -498,24 +498,13 @@ i915_gem_object_create_shmem(struct drm_i915_private *i915, u64 size) obj->write_domain = I915_GEM_DOMAIN_CPU; obj->read_domains = I915_GEM_DOMAIN_CPU; - if (HAS_LLC(i915)) - /* On some devices, we can have the GPU use the LLC (the CPU - * cache) for about a 10% performance improvement - * compared to uncached. Graphics requests other than - * display scanout are coherent with the CPU in - * accessing this cache. This means in this mode we - * don't need to clflush on the CPU side, and on the - * GPU side we only need to flush internal caches to - * get data visible to the CPU. - * - * However, we maintain the display planes as UC, and so - * need to rebind when first used as such. - */ - cache_level = I915_CACHE_LLC; - else - cache_level = I915_CACHE_NONE; - - i915_gem_object_set_cache_coherency(obj, cache_level); + /* + * Note that userspace has control over cache-bypass + * via its command stream, so even on LLC architectures + * we have to flush out the CPU cache to memory to + * clear previous contents. + */ + i915_gem_object_set_cache_coherency(obj, I915_CACHE_NONE); trace_i915_gem_object_create(obj);