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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 7C7CDCC6B0E for ; Tue, 13 Oct 2026 14:44:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 93D0B10E083; Tue, 13 Oct 2026 14:44:46 +0000 (UTC) Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9255E10E083 for ; Tue, 13 Oct 2026 14:44:39 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id B59D8602C3; Tue, 13 Oct 2026 14:44:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 155CC1F000FF; Tue, 13 Oct 2026 14:44:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791902678; bh=S5XZjEefQh4EdB8bPyGtES7lAp11auEruiseyw9G5YA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=G67LPayEaPri6jX7U5aHSF1SoPf+InmeNCiNXfrvN6JmLfx/cThKUlw47VO475TOm 5AujQBlSTAePAMTMZF7yiBJF633Y6PyePVnEcLi/EEBMB8T5ptdGj/0HhhELA7XoB3 d6txSnyju2ccA6ICBkVPOs9xwrFub1e4Z5dwygC2S4dePYWGtal9bWQOxsO39e6FsY 8vEFBFKZuy7hSw9YImsrCi+qmqlkI4emnqAUbQDAx/TgZlXjx8z9GbG5rYQv7AJ/Nq 90AjfRnX2WMX4spgriJFjhOkwcoDakw1F00ny8fM7/caqQFEicyDIJopG1yqNxDtGu um6rpmKSMRaCg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v11 01/19] PCI/P2PDMA: Honor device-specific ACS redirection To: "Leon Romanovsky" Cc: linux-pci@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, kvm@vger.kernel.org, media-ci@linuxtv.org In-Reply-To: <20261013-fix-p2p-acs-v4-0-v11-1-72cf8c96e617@nvidia.com> References: <20261013-fix-p2p-acs-v4-0-v11-0-72cf8c96e617@nvidia.com> <20261013-fix-p2p-acs-v4-0-v11-1-72cf8c96e617@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 13 Oct 2026 14:44:37 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] pci/p2pdma: deadlock in calc_map_type_and_dist() calling xa_store(= ) from softirq -- commit 6120f97b22446453f3e4fa09135e1a44135ecfe8 Author: Leon Romanovsky PCI/P2PDMA: Honor device-specific ACS redirection This commit updates PCI P2PDMA to respect device-specific ACS redirection quirks for switches and ports that redirect peer-to-peer traffic without a standard ACS capability. It queries quirks to set Request and Completion Redirect flags and modifies how affected ports are warned about. > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 45260423dfb09..ba94b0f339285 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c [ ... ] > @@ -782,15 +867,8 @@ calc_map_type_and_dist(struct pci_dev *provider, str= uct pci_dev *client, > goto done; > } > =20 > - if (verbose) { > - /* Drop the final semicolon; the list is not empty here */ > - if (!seq_buf_has_overflowed(&acs_list)) > - acs_list.buffer[acs_list.len - 1] =3D '\0'; > - pci_warn(client, "ACS redirect is set between the client and provider = (%s)\n", > - pci_name(provider)); > - pci_warn(client, "to disable ACS redirect for this path, add the kerne= l parameter: pci=3Ddisable_acs_redir=3D%s\n", > - seq_buf_str(&acs_list)); > - } > + if (verbose) > + pci_p2pdma_warn_redir(client, provider, &acs_list, &quirk_list); > =20 > map_through_host_bridge: > if (!cpu_supports_p2pdma() && [Severity: High] Does calling xa_store() further down in this function risk a deadlock? The map_types xarray is initialized with a plain xa_init() (without XA_FLAGS_LOCK_IRQ) in pcim_p2pdma_init(). This means its internal lock operates as a simple process-context spin_lock. Since calc_map_type_and_dist() can be called from softirq/hardirq context during P2P DMA mapping (e.g., via dma_map_sg()), and xa_store() takes the xarray lock without disabling interrupts, a process-context thread interrup= ted by a DMA mapping on the same CPU could cause a deadlock if they both try to access this xarray: drivers/pci/p2pdma.c:calc_map_type_and_dist() { ... done: rcu_read_lock(); p2pdma =3D rcu_dereference(provider->p2pdma); if (p2pdma) xa_store(&p2pdma->map_types, map_types_idx(client), xa_mk_value(map_type), GFP_ATOMIC); rcu_read_unlock(); return map_type; } --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261013-fix-p2p-ac= s-v4-0-v11-0-72cf8c96e617@nvidia.com?part=3D1