From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B539B3E5598; Wed, 5 Aug 2026 09:02:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785920567; cv=none; b=jalSjq4hsBvxmpP5XJ6ThV4ku01+WWcVZdDYNG8/GRm/evOdBeKEhRnDPJHkvs7BPXHSsesWhtr2aLaJ3P+343CFElZWmwGhqXEFH69T/QEbikpqI99qpMjgXIebWuo3gdNhE3US/q1MIzKVymPummnW1cfFDoAsGXgYtU8wqO8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785920567; c=relaxed/simple; bh=1KA8gPHKvZBs5uurLr0X4MWhBp7w/ZavaYHgWW2p3bA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gKczMsUdT9L8aoSSy4rYuEtlfgIN0aUK1ldXYiBWgUsskUI5ynU0GmaK+aTBkk89n1YwRrTpA9/h8q6gP6C2rpmshHec+7U5Ip+aCTYT/bFgBsBE95sjDpvYPz3eh2xBQdArydVEcOBd6ipHhc6iUhScyHzTo/LtQlKxwaX74Kg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lKD37hlv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lKD37hlv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A76491F00A3A; Wed, 5 Aug 2026 09:02:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785920564; bh=ToyNKMsiXdhJOroO6GPBchoHVXWBFgFS6VzMfpL4Mq8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=lKD37hlvBRSXPHrsNiklYY0huMziFqO/He9M0ZxXUzeMrW+o84iNjvf42MsjWODGs ls2K5UuVrzdasIljwY2FPBJCz+sZ5BaX7NQLEuE/+phZBFL0REGdUFNIlPTznDzyDV Ub0PDsticzVcJvsCA6+vrcZqKZn/QAAuAeVvmidvuS+1wX4tZY8F8gSfJBPlLA/s4V 6poEOdtQQ6aEQ1afvfRuxwVymQuwu5BpXtM9Gwggero7FLHBOyhJDFjCgGsTu8wV8d Kt4uBx+60CI9MS9WjYJdtJriiJiQKDwn2a3W5FyBUMTcPCk95Lfa4aZg8VVLKF5vxK wAQJX7nsc4Rhg== Date: Wed, 5 Aug 2026 12:02:39 +0300 From: Leon Romanovsky To: Logan Gunthorpe Cc: Bjorn Helgaas , Jonathan Corbet , Shuah Khan , Alex Williamson , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH 09/13] PCI/P2PDMA: Document ACS egress control handling Message-ID: <20260805090239.GB23431@unreal> References: <20260802-fix-p2p-acs-v1-0-a7c5eb64fff6@nvidia.com> <20260802-fix-p2p-acs-v1-9-a7c5eb64fff6@nvidia.com> <748b76b4-0a07-4145-87e2-9991412f0401@deltatee.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <748b76b4-0a07-4145-87e2-9991412f0401@deltatee.com> On Tue, Aug 04, 2026 at 04:01:41PM -0600, Logan Gunthorpe wrote: > > > On 2026-08-02 09:09, Leon Romanovsky wrote: > > +ACS P2P Egress Control does not by itself force a transaction upstream. A > > +clear Egress Control Vector bit for the peer port permits direct routing; a > > +set bit redirects the request upstream when P2P Request Redirect is enabled. > > +When Request Redirect is disabled, a set vector bit causes an ACS Violation > > +instead. The kernel evaluates these controls together and routes P2P DMA > > +through the host bridge when the direct path is blocked or cannot be > > +determined. > > One small nit here: I'd put commas around "by itself" to make it read a > little easier: > > "ACS P2P Egress Control does not, by itself, force a transaction..." > > Other than that: > > Reviewed-by: Logan Gunthorpe Thanks for the review. I understand the effort involved and truly appreciate it.