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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FAKE_REPLY_C,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 23181C43603 for ; Tue, 10 Dec 2019 21:23:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8A4020836 for ; Tue, 10 Dec 2019 21:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576012987; bh=jgZTmZ2JHLxkkhkw15N7CWxyAqm2EjktUnApqMjONyY=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=CXnXDkB7TyjJYUBPQ5Q3z5znTzcdWfQ+BWjR02l/KKpyEKSqiOEqRnF9wzyX8ENwA qEB7Nj04+2r2wsuKD2BIQmPSzNZhXmL3jqVS4eLTg4Q+hdpUn3V5On1pRb55DGsXaB zcogO5kDlx7RZaf+9uI8g+oOqFtXwJ8NERmZtt3g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728750AbfLJVXC (ORCPT ); Tue, 10 Dec 2019 16:23:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:53090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728920AbfLJVXB (ORCPT ); Tue, 10 Dec 2019 16:23:01 -0500 Received: from localhost (mobile-166-170-223-177.mycingular.net [166.170.223.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 06E8D205C9; Tue, 10 Dec 2019 21:22:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576012980; bh=jgZTmZ2JHLxkkhkw15N7CWxyAqm2EjktUnApqMjONyY=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=X7ANq6rpHSZ3n/QITEPYW2/gTZgG9Llo1ZR//ZMXcNQPBid9RbsYMc323lO4z5Pz7 C9ubTOu/wkaH9vJlvmYEpdTUinlko+x+8gj+JBgPql729UFvy2wMvFFXWD3TmpbcFS TfLEb0jw/zhoOcGY0FlaiW1hrY4Of5SqwGzyEZOI= Date: Tue, 10 Dec 2019 15:22:58 -0600 From: Bjorn Helgaas To: Armen Baloyan Cc: logang@deltatee.com, armbaloyan@gmail.com, epilmore@gigaio.com, linux-pci@vger.kernel.org Subject: Re: [PATCH] PCI/P2PDMA: Add Intel SkyLake-E to the whitelist Message-ID: <20191210212258.GA144914@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1575669165-31697-1-git-send-email-abaloyan@gigaio.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, Dec 06, 2019 at 01:52:45PM -0800, Armen Baloyan wrote: > Intel SkyLake-E was successfully tested for p2pdma > transactions spanning over a host bridge and PCI > bridge with IOMMU on. > > Signed-off-by: Armen Baloyan Applied with Logan's reviewed-by to pci/p2pdma for v5.6, thanks! Logan, the commit log for 494d63b0d5d0 ("PCI/P2PDMA: Whitelist some Intel host bridges") says: Intel devices do not have good support for P2P requests that span different host bridges as the transactions will cross the QPI/UPI bus and this does not perform well. Therefore, enable support for these devices only if the host bridges match. Add Intel devices that have been tested and are known to work. There are likely many others out there that will need to be tested and added. That suggests it's possible that P2P DMA may actually work but with poor performance, and that you only want to add host bridges that work with good performance to the whitelist. Armen found that it *works*, but I have no idea what the performance was. Do you care about the performance, or is this a simple "works / doesn't work" test? > --- > drivers/pci/p2pdma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 79fcb8d8f1b1..9f8e9df8f4ca 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -324,6 +324,9 @@ static const struct pci_p2pdma_whitelist_entry { > /* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */ > {PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE}, > {PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE}, > + /* Intel SkyLake-E. */ > + {PCI_VENDOR_ID_INTEL, 0x2030, 0}, > + {PCI_VENDOR_ID_INTEL, 0x2020, 0}, > {} > }; > > -- > 2.16.5 >