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=-3.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 B2378C43387 for ; Sat, 29 Dec 2018 02:29:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 722CD218FD for ; Sat, 29 Dec 2018 02:29:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546050573; bh=7ma79gBOvRlxzIEkh/eueZWE2pLUkmMSUErSOoXNWAQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=s5vkDgSAAJSMIoD5Wq9X6FcYNwcnyvAMJHZZ9PbFMzRFHm5zPbIqyVGeeoDFjHzC0 +l8ZMV59piPabTHBdXHj2CborTdhIxGvUUnWj4dfnWaGq4AS498/1/jXVMjGg1IiUX S2E6vA+6siEkr9CieHa33QoLbtfT8LSUnfb7C7pk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727240AbeL2C3c (ORCPT ); Fri, 28 Dec 2018 21:29:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:43928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727208AbeL2C3c (ORCPT ); Fri, 28 Dec 2018 21:29:32 -0500 Received: from localhost (unknown [69.71.4.100]) (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 2FDB42146F; Sat, 29 Dec 2018 02:29:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546050571; bh=7ma79gBOvRlxzIEkh/eueZWE2pLUkmMSUErSOoXNWAQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ewypNhDQHgaurMsd8QBaJupDj2Ssyyj73DEY2Da2xX6rX06J7f0oV4EyJiblP64Lc xP6/jSNkvwOj/uLvF5uu7EoYLbGxCP4CKDIb5kNLILrvDLUzHZKM4m4yjY9Qqq6aG2 1aeiSJk/cQjevHffChWDP9h2h5qVDx9zRmcbTrdY= Date: Fri, 28 Dec 2018 20:29:23 -0600 From: Bjorn Helgaas To: yu Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Logan Gunthorpe , Stephen Bates , Jonathan Cameron , Eric Wehage , Alexander Duyck Subject: Re: How to force RC to forward p2p TLPs Message-ID: <20181229022923.GA159477@google.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 [+cc Logan, Stephen, Jonathan, Eric, Alex] On Sat, Dec 22, 2018 at 12:50:19PM +0800, yu wrote: > Hi all, > > We have a PCIE card which has a PEX8732 switch on-board, and there > are two endpoint SOCs like graphic decoder behind the switch, and by > default the ACS is enabled in 8732. > > We use the p2p DMA to transfer data between these two endpoint SOCs, > and if the host server is not enable ACS in BIOS, the p2p works well, > but when ACS is enabled in BIOS, the p2p is always failed. With the > help of a protocol analyzer, we can see that the TLP is redirected to > RC, and RC just discard it. > > I tried to find how to make RC forward redirected TLP to its original > target, but nothing found, it seems this is highly related to the RC > vendors. > > In the PCIE 4.0 spec, the section of the RC behavior of the p2p > request redirect said that ''implementation-specific logic within the > RC that determines whether the request is directed towards its > original target, or blocked as an ACS Violation error. the algorithms > and specific controls for making this determination are not > architected by this spec''. > > > So is there some spec or document to describe how to set the RC? Any > suggestion is appreciated. Not that I'm aware of, but the folks I cc'd would know a lot more about this area. Bjorn