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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 78BFACAC5B9 for ; Tue, 30 Sep 2025 07:31:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D338F8E001C; Tue, 30 Sep 2025 03:31:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CE40D8E0002; Tue, 30 Sep 2025 03:31:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BD3628E001C; Tue, 30 Sep 2025 03:31:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id AA2418E0002 for ; Tue, 30 Sep 2025 03:31:01 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 5F90544472 for ; Tue, 30 Sep 2025 07:31:01 +0000 (UTC) X-FDA: 83945095122.26.AA0AACD Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf26.hostedemail.com (Postfix) with ESMTP id B7F2B14000E for ; Tue, 30 Sep 2025 07:30:59 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=F87Yad04; spf=pass (imf26.hostedemail.com: domain of leon@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=leon@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1759217459; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=L9yqnF4M+qCDA9000pqzfMg6QdUSOLGidqM7b5HtStE=; b=cNslElxJfk+6RlMRHrGB3E7zXR+GwK65byaiP9GHNPkn1AkkzgkONUT6qkkL1/GxMMGurk BzqzzNuGEG7DjZISNkua7Zpt01jf4xlCWQowSWNo3xb4vxllHINsfMpVpT1WcDh/paOxXH I7QnubUClhrDVf3OXQyPlMq3J+5Y4Vg= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=F87Yad04; spf=pass (imf26.hostedemail.com: domain of leon@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=leon@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1759217459; a=rsa-sha256; cv=none; b=LSLDZRib4FIGe5+c78wkkml1iXKUxtYDf7XXSptUkc65bT1iIbTtgwMjdURA9a4q2U2loM uM/JELHzPGN4GMnPb+yrMGCV3Xnom+LdZt0oVELDexA1Sw8VSv37io+VKkqVfXa0LHJVyI LLYlzdmpSQx1xBgfm1if1XQasO/ry3A= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id D398A603F3; Tue, 30 Sep 2025 07:30:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B71C8C113D0; Tue, 30 Sep 2025 07:30:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759217458; bh=JQzf0lGVVh7uBp1GGrgRG3aOLt81vd3Z1vJ+MdzJaUg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F87Yad04oYGKqR0yrv700Kdv7cMA7yYANQZWxSzZfBGzhhGL/AY0n38vF/CbS1+uS xoHf7BEDW8mOIaQN7Wk/lwIKl4Yr4ZCcSIRmUMKAIta02I34naQImlmh2K8ES0+J0J 37JGfcZ5Fcjrg+XvYNzoB1zs1jcuvaeDiG8rOpUd6KE1U67TY/2JY6hYEFcEF+3s0j KRocY0sJEKrIBIPmUsJmcRcbzwrkU9tKLg/YjlOL+FaI0JgPnlof0Me1fLbHLHzT1r DpZwl2Lrtc0E2Q7+85ZBPdg92JKatMeAQHBu3PCoTknvQScfYkwgCaBKVjyqnL/Fk+ VbrIksbpXUNYQ== Date: Tue, 30 Sep 2025 10:30:53 +0300 From: Leon Romanovsky To: Alex Williamson Cc: Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , Christian =?iso-8859-1?Q?K=F6nig?= , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, Jens Axboe , Joerg Roedel , kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Logan Gunthorpe , Marek Szyprowski , Robin Murphy , Sumit Semwal , Vivek Kasireddy , Will Deacon Subject: Re: [PATCH v4 08/10] vfio/pci: Enable peer-to-peer DMA transactions by default Message-ID: <20250930073053.GE324804@unreal> References: <20250929151745.439be1ec.alex.williamson@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250929151745.439be1ec.alex.williamson@redhat.com> X-Stat-Signature: ysf7akfpw79uu5e9yr1jcixrw59p5h9f X-Rspam-User: X-Rspamd-Queue-Id: B7F2B14000E X-Rspamd-Server: rspam04 X-HE-Tag: 1759217459-736350 X-HE-Meta: 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 fD/Mr//n fwsbKOgc04t3CmCbxB5hVKPewlOsf7/US1/ptpVm1PVd90OkbrBLzvnTOrhVkLoKi9HwxrlefQKQDO3EV+FVJzIdgtDWsz3kWsdKmWizka+du4kMxO4E7VUSMpDANj2jZD9SCVF/83o54n9uYSiKi5nK3Ql91iAAl02Xr8uZ7+2a4XuYEOnxU/y77wnzwgMDm3XO7Hom0rdKllhsRc7obfTx7lVxgI8eRTQGevvi1aFWmiq4o+VI/NOqaoitKJ/CmESrrACnc4YXqrwyk6uKlGxJ3VjQMtoRKKJs/6NfLwkJvBp0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 29, 2025 at 03:17:45PM -0600, Alex Williamson wrote: > On Sun, 28 Sep 2025 17:50:18 +0300 > Leon Romanovsky wrote: > > > From: Leon Romanovsky > > > > Make sure that all VFIO PCI devices have peer-to-peer capabilities > > enables, so we would be able to export their MMIO memory through DMABUF, > > > > Signed-off-by: Leon Romanovsky > > --- > > drivers/vfio/pci/vfio_pci_core.c | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c > > index 7dcf5439dedc..608af135308e 100644 > > --- a/drivers/vfio/pci/vfio_pci_core.c > > +++ b/drivers/vfio/pci/vfio_pci_core.c > > @@ -28,6 +28,9 @@ > > #include > > #include > > #include > > +#ifdef CONFIG_VFIO_PCI_DMABUF > > +#include > > +#endif > > #if IS_ENABLED(CONFIG_EEH) > > #include > > #endif > > @@ -2085,6 +2088,7 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) > > { > > struct vfio_pci_core_device *vdev = > > container_of(core_vdev, struct vfio_pci_core_device, vdev); > > + int __maybe_unused ret; > > > > vdev->pdev = to_pci_dev(core_vdev->dev); > > vdev->irq_type = VFIO_PCI_NUM_IRQS; > > @@ -2094,6 +2098,11 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) > > INIT_LIST_HEAD(&vdev->dummy_resources_list); > > INIT_LIST_HEAD(&vdev->ioeventfds_list); > > INIT_LIST_HEAD(&vdev->sriov_pfs_item); > > +#ifdef CONFIG_VFIO_PCI_DMABUF > > + ret = pcim_p2pdma_init(vdev->pdev); > > + if (ret) > > + return ret; > > +#endif > > init_rwsem(&vdev->memory_lock); > > xa_init(&vdev->ctx); > > > > What breaks if we don't test the return value and remove all the > #ifdefs? The feature call should fail if we don't have a provider but > that seems more robust than failing to register the device. Thanks, pcim_p2pdma_init() fails if memory allocation fails, which is worth to check. Such failure will most likely cause to non-working vfio-pci module anyway, as failure in pcim_p2pdma_init() will trigger OOM. It is better to fail early and help for the system to recover from OOM, instead of delaying to the next failure while trying to load vfio-pci. CONFIG_VFIO_PCI_DMABUF is mostly for next line "INIT_LIST_HEAD(&vdev->dmabufs);" from the following patch. Because that pcim_p2pdma_init() and dmabufs list are coupled, I put CONFIG_VFIO_PCI_DMABUF on both of them. Thanks > > Alex > >