From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B96E4C05027 for ; Mon, 20 Feb 2023 08:39:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EEEBF10E60B; Mon, 20 Feb 2023 08:39:19 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 738B610E602; Mon, 20 Feb 2023 08:39:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1676882357; x=1708418357; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=9IXP+XFabQzHOD20B+FIU39rW4y7pK+ccbQg35ljD2Y=; b=DLiqXb4eMjVcQ8N8Q64wjSXameOUBxcn+cJvA4Nekmu0B+9EBB+K5pXP jEWBO3F125tZL0hFYpZ0crqTT6fFveDwpJJznoj+4oBYFHFuKa91vs/eI IaGD0f37FOuKsNMumMufcGUyT4X21ThZQ1gLUCishJMPEp1Hz0yGha1uB NBfZUgOw+/FOfpk1bMeC6h15195PMXTKXL73AmzZrKvUtEU5ltcHvDr03 5Sh828jIdAZJqZzT4LV3v8iNB/28CRvOyqN3dDo9a9c3RKlrpDjQZBas/ ImjWZiO7JSFoUn5ITKexq008/Hc05Rtl8O5/gUauf2MDGwWa1NAz4HKji A==; X-IronPort-AV: E=McAfee;i="6500,9779,10626"; a="332356485" X-IronPort-AV: E=Sophos;i="5.97,311,1669104000"; d="scan'208";a="332356485" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2023 00:39:11 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10626"; a="760085739" X-IronPort-AV: E=Sophos;i="5.97,311,1669104000"; d="scan'208";a="760085739" Received: from mochoamo-mobl.ger.corp.intel.com (HELO [10.213.211.126]) ([10.213.211.126]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2023 00:39:02 -0800 Message-ID: <05e66d0e-3af1-83c9-f52a-5b5be722e573@linux.intel.com> Date: Mon, 20 Feb 2023 08:39:00 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Content-Language: en-US To: John.C.Harrison@Intel.com, Intel-GFX@Lists.FreeDesktop.Org References: <20230216011101.1909009-1-John.C.Harrison@Intel.com> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc In-Reply-To: <20230216011101.1909009-1-John.C.Harrison@Intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Intel-gfx] [PATCH v3 0/2] Don't use stolen memory or BAR mappings for ring buffers X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: DRI-Devel@Lists.FreeDesktop.Org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 16/02/2023 01:10, John.C.Harrison@Intel.com wrote: > From: John Harrison > > Instruction from hardware arch is that stolen memory and BAR mappings > are unsafe for use as ring buffers. There can be issues with cache > aliasing due to the CPU access going to memory via the BAR. So, don't > do it. > > v2: Dont use BAR mappings either. > Make conditional on LLC so as not to change platforms that don't need > to change (Daniele). > Add 'Fixes' tags (Tvrtko). > v3: Fix dumb typo. > > Signed-off-by: John Harrison > > > John Harrison (2): > drm/i915: Don't use stolen memory for ring buffers with LLC > drm/i915: Don't use BAR mappings for ring buffers with LLC > > drivers/gpu/drm/i915/gt/intel_ring.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) It is doing what it laid out as the problem statement so series looks good to me. Acked-by: Tvrtko Ursulin Regards, Tvrtko