From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) (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 32816339719; Tue, 4 Aug 2026 22:01:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=204.191.154.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785880905; cv=none; b=KWF5JkrLpKtUDlYHgN1LXEGjJhnwMfSs42+X6mviDnN0Xv31OLJUha/+nSNYbD9x3TK2lg/CmhPqNQxgGcDqlWbgnawr6ImuJPUKS5y07T8ImMBjDjxhaBW+tPFIxN+No5W+RaL3ZOjfcxZD2I4VKthtIBM1dlcSfHpW1Wi3EJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785880905; c=relaxed/simple; bh=Jw9XDHWQpOb2TGg8xY2+gVNbXYm9BqS/vElJR1qqn4I=; h=Message-ID:Date:MIME-Version:To:Cc:References:From:In-Reply-To: Content-Type:Subject; b=nt+8CXZP3D9Q6pRXMJIYASAANf6Dc4+lqqv+3SJkR9g3KnmZh3z4NjysH3cfrSmLsVZA+0ViQ3KWAKq2raLGzWtRStwA+zlGeC2L6OjZScREue50bKbbW3WCM2f2oYO10qj7XUnFA7p9VfjjH4m2TmU9U2p70iirp2BFjcznsUg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com; spf=pass smtp.mailfrom=deltatee.com; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b=l5HUxPN6; arc=none smtp.client-ip=204.191.154.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=deltatee.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b="l5HUxPN6" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=Jw9XDHWQpOb2TGg8xY2+gVNbXYm9BqS/vElJR1qqn4I=; b=l5HUxPN6LhX1A46iN9qGLgpTMr SIzs9AOTTZNHbwARQmy7R3qQ6ptEnM+xSUlj5OLZZmVnOh1Ox1AWn+Nm3aFpwG697EFyJOCht6gce NaOGvmSVVWAcudFPqanHKN1ViCCEfhhuvXAu9YmcPt/7Lkb/kh7jgIbE+CkgAB9Rcs8lI1UR2HoLo YEuwTPpDvBm9gVHPJtxlr7aN4DF4gfgSxmVUGCUC6/Y0SQRfZ4LnmQz8kzLSp17nAS87/27jqJY+U l+faw0oHp0zkgTcQTohLIDkm8mybRWo5JN5vu09MQTLRjeLTUHBUZ8sHcpvfBqc5sXSH7UDksQ8l7 /mU65JBQ==; Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.98.2) (envelope-from ) id 1wrNCg-000000002WI-0Zaj; Tue, 04 Aug 2026 16:01:42 -0600 Message-ID: <748b76b4-0a07-4145-87e2-9991412f0401@deltatee.com> Date: Tue, 4 Aug 2026 16:01:41 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Leon Romanovsky , Bjorn Helgaas , Jonathan Corbet , Shuah Khan , Alex Williamson Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org References: <20260802-fix-p2p-acs-v1-0-a7c5eb64fff6@nvidia.com> <20260802-fix-p2p-acs-v1-9-a7c5eb64fff6@nvidia.com> Content-Language: en-CA From: Logan Gunthorpe In-Reply-To: <20260802-fix-p2p-acs-v1-9-a7c5eb64fff6@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: leon@kernel.org, bhelgaas@google.com, corbet@lwn.net, skhan@linuxfoundation.org, alex@shazbot.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org X-SA-Exim-Mail-From: logang@deltatee.com X-Spam-Level: Subject: Re: [PATCH 09/13] PCI/P2PDMA: Document ACS egress control handling X-SA-Exim-Version: 4.2.1 (built Sun, 23 Feb 2025 07:57:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) 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