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 X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 535CDC433E5 for ; Thu, 23 Jul 2020 20:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A121207BB for ; Thu, 23 Jul 2020 20:11:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b="F15X1O9w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726977AbgGWULA (ORCPT ); Thu, 23 Jul 2020 16:11:00 -0400 Received: from ale.deltatee.com ([204.191.154.188]:43046 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725894AbgGWULA (ORCPT ); Thu, 23 Jul 2020 16:11:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Sender: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=v1ayK2JNh09cbcXMchXBkeJUQfzVRgEw+NVUe/9qPvM=; b=F15X1O9wGoAqnElKkbPU/X/h7P 0QrI67MnbBQtdFQ06AWBIGKgDvDuXhUWVxuFLEcaI9M8N5cKBVaUIUJYfH2pBLYQSdgebxw/GcSJD twcHe8RmiW7EF923JFIMQZhgKYkv21HvAd1feR5/W6AaC5qM/uyhKzzhJIBh42Ew8WuQldAJWRLta rm7ZCNBtUQcz5FQH80GfIpCxvkJVh21oqcVhNNVoV2tz7V4tpVte9p/dqrIbALLW2FPrwsaIQtKwv /qwlXyK1WuAEQCBuUioWRt2bppy2e6n8qCBtfQD3PGudulEZnZUfv/vHX1VlPQ8lsfTH2PoQgGgq2 GS9x3Lpg==; Received: from s01060023bee90a7d.cg.shawcable.net ([24.64.145.4] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jyhYM-0002SK-JP; Thu, 23 Jul 2020 14:10:55 -0600 To: Bjorn Helgaas , Alex Deucher Cc: LKML , Linux PCI , Bjorn Helgaas , =?UTF-8?Q?Christian_K=c3=b6nig?= , Huang Rui , Andrew Maier , "H. Peter Anvin" References: <20200723195742.GA1447143@bjorn-Precision-5520> From: Logan Gunthorpe Message-ID: <89d853d1-9e45-1ba5-5be7-4bbce79c7fb8@deltatee.com> Date: Thu, 23 Jul 2020 14:10:52 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200723195742.GA1447143@bjorn-Precision-5520> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 24.64.145.4 X-SA-Exim-Rcpt-To: hpa@zytor.com, andrew.maier@eideticom.com, ray.huang@amd.com, christian.koenig@amd.com, bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, alexdeucher@gmail.com, helgaas@kernel.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH] PCI/P2PDMA: Add AMD Zen 2 root complex to the list of allowed bridges X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-07-23 1:57 p.m., Bjorn Helgaas wrote: > [+cc Andrew, Armen, hpa] > > On Thu, Jul 23, 2020 at 02:01:17PM -0400, Alex Deucher wrote: >> On Thu, Jul 23, 2020 at 1:43 PM Logan Gunthorpe wrote: >>> >>> The AMD Zen 2 root complex (Starship/Matisse) was tested for P2PDMA >>> transactions between root ports and found to work. Therefore add it >>> to the list. >>> >>> Signed-off-by: Logan Gunthorpe >>> Cc: Bjorn Helgaas >>> Cc: Christian König >>> Cc: Huang Rui >>> Cc: Alex Deucher >> >> Starting with Zen, all AMD platforms support P2P for reads and writes. > > What's the plan for getting out of the cycle of "update this list for > every new chip"? Any new _DSMs planned, for instance? Well there was an effort to add capabilities in the PCI spec to describe this but, as far as I know, they never got anywhere, and hardware still doesn't self describe with this. > A continuous trickle of updates like this is not really appealing. So > far we have: > > 7d5b10fcb81e ("PCI/P2PDMA: Add AMD Zen Raven and Renoir Root Ports to whitelist") > 7b94b53db34f ("PCI/P2PDMA: Add Intel Sky Lake-E Root Ports B, C, D to the whitelist") > bc123a515cb7 ("PCI/P2PDMA: Add Intel SkyLake-E to the whitelist") > 494d63b0d5d0 ("PCI/P2PDMA: Whitelist some Intel host bridges") > 0f97da831026 ("PCI/P2PDMA: Allow P2P DMA between any devices under AMD ZEN Root Complex") > > And that's just from the last year, not including this patch. Yes, it's not ideal. But most of these are adding old devices as people test and care about running on those platforms -- a lot of this is bootstrapping the list. I'd expect this to slow down a bit as by now we have hopefully got a lot of the existing platforms people care about. But we'd still probably expect to be adding a new Intel and AMD devices about once a year as they produce new hardware designs. Unless, the Intel and AMD folks know of a way to detect this, or even to query if a root complex is newer than a certain generation, I'm not sure what else we can do here. Logan