From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bmailout2.hostsharing.net (bmailout2.hostsharing.net [83.223.78.240]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00AC82264DD; Thu, 19 Jun 2025 12:48:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=83.223.78.240 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750337290; cv=none; b=n5+oe1sfqyk6FasUpAXEC1uLssYIwo9B0T2PedA1Yxg083ziCxEPe470WLAwcGPVNM1h01hTMpLQPzYPO5kyoD0tFZw6iQZ/azzOrMFxvpaaif8GiZf2Aex8/qVCq/k05XeJH1kky1/XH5QKWsHrPb0SZ90MhjKRv9MmaxsuB/s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750337290; c=relaxed/simple; bh=YPBcfanuB90YKI8TPFHCaI34/Yp2+h2LvdXi0kDJkeQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s/8FPnm/ckliGbMvM7ZzQ9A6/ymrNylGABFOjhzRf5aihDrss+00wAPGrxoYKuNsye745eeIrpXZuV/z/69hQf26+7n2P9N2I4olUrwlsAYjamoJattYiKx1PZ7K8vKhtssSD1levxbzcMzuLlCYL6YrQXUP88FbjRDWXgyy4mk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de; spf=none smtp.mailfrom=h08.hostsharing.net; arc=none smtp.client-ip=83.223.78.240 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=h08.hostsharing.net Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "*.hostsharing.net", Issuer "RapidSSL TLS RSA CA G1" (verified OK)) by bmailout2.hostsharing.net (Postfix) with ESMTPS id 05D142009D10; Thu, 19 Jun 2025 14:48:05 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id F28BF3A080B; Thu, 19 Jun 2025 14:48:04 +0200 (CEST) Date: Thu, 19 Jun 2025 14:48:04 +0200 From: Lukas Wunner To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= Cc: Manivannan Sadhasivam , Dan Williams , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/1] PCI: Add Extended Tag + MRRS quirk for Xeon 6 Message-ID: References: <20250610114802.7460-1-ilpo.jarvinen@linux.intel.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250610114802.7460-1-ilpo.jarvinen@linux.intel.com> On Tue, Jun 10, 2025 at 02:48:02PM +0300, Ilpo Järvinen wrote: > When bifurcated to x2, Xeon 6 Root Port performance is sensitive to the > configuration of Extended Tags, Max Read Request Size (MRRS), and 10-Bit > Tag Requester (note: there is currently no 10-Bit Tag support in the > kernel). While those can be configured to the recommended values by FW, > kernel may decide to overwrite the initial values. > > Add a quirk that disallows enabling Extended Tags and setting MRRS > larger than 128B for devices under Xeon 6 Root Ports if the Root Port > is bifurcated to x2. Use the host bridge's enable_device hook to > overwrite MRRS if it's set to >128B for the device to be enabled. > > The earlier attempts to implement this quirk polluted PCI core code > with the checks necessary to support this quirk. Using the > enable_device hook keeps the quirk well-contained, away from the PCI > core code. > > Suggested-by: Lukas Wunner > Link: https://cdrdv2.intel.com/v1/dl/getContent/837176 > Signed-off-by: Ilpo Järvinen Reviewed-by: Lukas Wunner Patch looks perfect to me and could go in either through pci or tip. For the record, link to previous attempt to solve this: https://lore.kernel.org/r/20250422130207.3124-1-ilpo.jarvinen@linux.intel.com/ Thanks, Lukas