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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5D90AC71136 for ; Wed, 11 Jun 2025 22:18:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mp3tpEUI/np35pt2H813TEIBhYFlhsTXQ2G6rjrZ/Pc=; b=2iPFjvpUGMn3jZgNV1cOwKRJ8c 6yIq39O4yCBKJw9nmN73SxQF/GRN/UI2VFnXom+wpWRi/Q4Hg9UXKFDEiAC0ZshC+7tWcSmhqagLB mH2mjQFl0Sa4PqcicP9F3BubazRmZ/QVuAbtHFQ3FXOqINzldthh3mW/2bgj5BwP37b3xGopcc7dV fdqObxaYiZ7eghQzD2zlvv3ltZWSKRurQavK1TE09+v6sGJHc0KR0C5N+gOKEdc6ZFQdVNM7v4GJn ZKzx3GoTbVeMi5HnVxxRr04ml3VK7/LhdxbXH2S/Sll/s/xdOkv+bXDzFZ6VwZ3Z8u0c4q1DyIOpA uL/7Q7TA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPTma-0000000BS8Q-0Gzg; Wed, 11 Jun 2025 22:18:56 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPRd3-0000000B7AS-1mDX for linux-nvme@bombadil.infradead.org; Wed, 11 Jun 2025 20:00:57 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=mp3tpEUI/np35pt2H813TEIBhYFlhsTXQ2G6rjrZ/Pc=; b=XHwGJnexCrJuLZkl8kphL+eRjC +GJAF7lhEmduQmErej+X25C8gT2qYV4WT6CP0mjDLWoW0C9XvfkYULMD+TUvLSZ4YrGlBW4Jr4Igy GTf4POlgtrptw8A9V8vyc0XvoyWk7GB5qKev+Xdj22yObK2JFmAta5vIeKq1CyaveUK3dZ0fZtDfl YnIfxg7zbI4xSpllrg71FOteik7GXwYMgKYHIJNwOwQkK4y1ynNiLiDbTxVzssovAJg922qMkq1uq dpBZJNiMbNvW/SaeYn4nU7NOFZJQXctLK0lrTwA1+Qg/CPJm11KdsfVgtG7vnZTY4zZs+kUvoufyo PjHairBg==; Received: from nyc.source.kernel.org ([147.75.193.91]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uPRcL-00000002VBI-49o7 for linux-nvme@lists.infradead.org; Wed, 11 Jun 2025 20:00:18 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 72159A51A42; Wed, 11 Jun 2025 20:00:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65EA0C4CEE3; Wed, 11 Jun 2025 20:00:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749672007; bh=ooKf35t5Mm4QWKAgMc0QQBD+koQKDB4/2gFAGm9zMdc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ck+I2qQ7CfveRuzjoUygtQAbhUev9wTDtalXJBJYaeFI1NWp1p3T8m9Lo+XSW51sx nL6rQT3JKRp/VjpxsW4Xovk+m+1lCN9eF3RB5dcERSzYSKyruti4+i7HTNjMEE5DWv EtkciBllqF5lL3Q/T69Iy0fa2e1V9BYWz4RbLaTa0nHDMDfAB4GqJiFvYJ3nSbb2/i aj8ic5bG7WCNsUnVcFHoHSKqvQpXnClUPcVsLxFDnNNgUEgy9o9KlX6jnRQVzw5tAf u3kuNNzbY2dCkq/R3+gpxQ3n7rWvnTWuMmwJl3WcvVXUuaRcj7UzchCXqdWuSg4fio cUZ7k8GC32Y0g== Date: Wed, 11 Jun 2025 14:00:04 -0600 From: Keith Busch To: Logan Gunthorpe Cc: Christoph Hellwig , Jens Axboe , Sagi Grimberg , Chaitanya Kulkarni , Kanchan Joshi , Leon Romanovsky , Nitesh Shetty , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH 1/9] block: don't merge different kinds of P2P transfers in a single bio Message-ID: References: <20250610050713.2046316-1-hch@lst.de> <20250610050713.2046316-2-hch@lst.de> <20250611034316.GA2869@lst.de> <5cddbda3-02bd-4dc1-9f7f-197279da6279@deltatee.com> <88fe6154-6086-409d-a180-665d62d72d47@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <88fe6154-6086-409d-a180-665d62d72d47@deltatee.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250611_210016_813218_BC26CA17 X-CRM114-Status: GOOD ( 12.82 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jun 11, 2025 at 01:41:54PM -0600, Logan Gunthorpe wrote: > On 2025-06-11 10:41, Keith Busch wrote: > > Is there some other mechansim that ensures a host memory mapped IOVA > > doesn't collide with a PCI bus address then? > > Yes, in the absence of a switch with ACS protection this can be a problem. > > I haven't looked at this in a long time, but the iommu drivers reserve > regions where the PCI addresses are valid so no iova will be allocated > with a similar bus address. After a quick search, I believe today, this > is handled by iova_reserve_pci_windows(). Excellent, I think that was the piece I was missing. Thanks!