From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) (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 0AB4C3FE367; Mon, 11 May 2026 14:59:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=67.231.145.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778511545; cv=none; b=K7nYPh6k6cZP/lZ0VyCBqpvj7Ie46HV/GXay4dpSU3fgjzvgy8fPcjAHZ+OZMRdROTxO0/Rv+6P6+q+V/Hn/NYUPrakCChyr9VVoOohOXftJn1ls9z58TwBZDQDxvT3akn3t1WfhXUeQaZBnqQHWiJiM+fxxQfFlWRKsDYQgcHQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778511545; c=relaxed/simple; bh=aS/viXDpnIcjuVwxw9cSHrU+kK1uzS4ma3eXzqx5OqY=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=RhC3xMhSs1LxybsnupPpEsVJIm2+6DbZk31IyntneG7ZrCaEwTFvrDJHbfHZby5HGTOUC/q6EFZNC6KbDk3V/btcd7Psee8U7x3YuOZRt4lZZTMCpe6NoRk3FB+VvBZ/9Y/5jBPJl4W51mR+x083P3LuZuMQGhwdPvBVeWQtvi0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com; spf=pass smtp.mailfrom=meta.com; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b=rSB/XxKJ; arc=none smtp.client-ip=67.231.145.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b="rSB/XxKJ" Received: from pps.filterd (m0528009.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 64BEwA761286452; Mon, 11 May 2026 07:58:52 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=cc :content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=s2048-2025-q2; bh=Mi7OHQLoUkr4cAFXSK 75uEyuAhLn6vXF3cQZija/bpg=; b=rSB/XxKJT7dfU0sYVhTW3WUalHQxDKu2OV QgX51bR02I23iww3DlWLa2h4XUptfsSbFBR2buUc41nfgiKS9U6e/nW01bBubnGL AUQ8HI9i0CL10XMPZxEhvT3LcYQ3Cs8xNIMxx3QWoMWW6wFDO4Cm5nY48hEZ4Hwq ji23MPfMKdixoeBwBPItesoZrJtFbi+Fhf4I7xpYfAJjozwCynryPP3mXXNoYqNT Wat6MgeYd/4bI6/4loGZEueV7OqffNKNBUCPdNbDD9ziOEsU4U18JnAygJAN4vZS 90dwPF0jDH3U1Lv4lupeRkEhcFs/ba9KPIxXA4bGu6P8u9Grllpw== Received: from maileast.thefacebook.com ([163.114.135.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 4e2pp66e3k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Mon, 11 May 2026 07:58:51 -0700 (PDT) Received: from localhost (2620:10d:c0a8:fe::f072) by mail.thefacebook.com (2620:10d:c0a9:6f::237c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.37; Mon, 11 May 2026 14:58:50 +0000 From: Matt Evans To: Alex Williamson , Kevin Tian , Jason Gunthorpe , Ankit Agrawal , Alistair Popple , Leon Romanovsky , Kees Cook , Shameer Kolothum , Yishai Hadas CC: Alexey Kardashevskiy , Eric Auger , Peter Xu , Vivek Kasireddy , Zhi Wang , , , Subject: [PATCH v5 0/3] vfio/pci: Request resources and map BARs at enable time Date: Mon, 11 May 2026 07:58:22 -0700 Message-ID: <20260511145829.2993601-1-mattev@meta.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-GUID: _e8Y9XhTCvtTMnDRdkIGMMavRFCh8Ob0 X-Authority-Analysis: v=2.4 cv=IP0yzAvG c=1 sm=1 tr=0 ts=6a01eeab cx=c_pps a=MfjaFnPeirRr97d5FC5oHw==:117 a=MfjaFnPeirRr97d5FC5oHw==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=U_y8lYiYyhHBU5rMqhb2:22 a=VwQbUJbxAAAA:8 a=VabnemYjAAAA:8 a=fFA4BOaLBG0vzsxRvVMA:9 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-ORIG-GUID: _e8Y9XhTCvtTMnDRdkIGMMavRFCh8Ob0 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTExMDE2NCBTYWx0ZWRfX2MMjYr1Lfes5 yc78wfAueWNyXlld4YtG6yksecXWavh9HTg8hEF7UiOvZYyiFf3uRy2zuAGjPBRcoJYx8F1QhUg EIDCfaLi+1luoCwZezo/rXpH8RdPMTpiMIWK3+YPS+4Ro6NOf0iYd1/eQClv1CkzPZclp1UCwPo IZ3MPd2V3v4SOKCuhhRCi16HYViZxq0FnnJj9m+tz3/lPf7ATXu1tbReZOQkI/fBs6nrL+D8buw cKO76tR7Co7puvRiOVp7Mrbfs33WdBw5KRtMJEDYqvi/9We6WRXyL0kVdbs9M7GcniYsLtC/QFh KsCzebxW39LS8lgj+WgMWW0V3gQQ9TFPe0Zbgj5HlooosJlf+qW2MjYjv4oaLU4xco60H4jQkTb qQyIG6Mhg5zwxSoQKqLnldMNGdK3o765eui1J3gIjQA412hDZmUtrQ8+3YUkZEd8wwEG9zRQMYi hdWY1WR4t4uCHAwm0Xw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-11_04,2026-05-08_02,2025-10-01_01 Hi, These patches fix a potential race for concurrent calls to vfio_pci_core_setup_barmap(), and a DMABUF missing check for resource before the export. Discussion on a previous series (different, replaced by this one) is here: https://lore.kernel.org/kvm/20260415181423.1008458-1-mattev@meta.com Responses in that thread indicated there wasn't a strong historical reason to require the mapping to be performed on-demand at BAR reference time. It's much simpler to move this earlier, to vfio_pci_core_enable(), and that then avoids having to deal with concurrent requests later. The first patch requests PCI resources and pci_iomap() of the BARs from vfio_pci_core_enable(), moving this out of vfio_pci_core_setup_barmap(). Some callers rely on vfio_pci_core_setup_barmap() for its ioremap() effect, and other callers use it for its resource-acquiring effect. The function turns into a cheap error check that both these actions have occurred; that maintains the same error behaviour as before the fix. The second patch adds a call to vfio_pci_core_setup_barmap() to VFIO DMABUF export to check the resource is reserved; previously this was able to export an unrequested resource. Although patch 1 at first appears to fix this by requesting resources at enable time, code using the BAR still needs to check the resource really was acquired. (FWIW, Leon gave a R-B on v2 in https://lore.kernel.org/kvm/20260426111606.GC440345@unreal/ though this repost isn't 100% identical so I didn't propagate it.) The third patch refactors vfio_pci_core_setup_barmap() plus the various vdev->barmap[] accesses into vfio_pci_core_get_iomap() which returns either a pointer to the mapping or an ERR_PTR() describing why it doesn't exist. This is used by callers that need the mapping, but also by other callers to check that the resource/mapping step was successful. === Changes === v5: - vfio_pci_core_map_bars() releases the region if the subsequent pci_iomap() fails - vfio_pci_core_disable() correctly tests for NULL/error - For nvgrace-gpu, check the result of vfio_pci_core_get_iomap() at open time then stash the BAR base for use later on. Errors are checked up-front, and this avoids the perception that a later ..._get_iomap() might fail. v4: https://lore.kernel.org/kvm/20260505173835.2324179-1-mattev@meta.com/ - Reorder patches to put fixes at the front: First, the early BAR setup to avoid the race. Then, add DMABUF check. Then, refactor/tidy. - Adjust Fixes: of first patch to point to early VFIO PCI commit, and reduce the patch to only the fix (don't add new error checks). Use pci_dbg() instead of pci_warn() when setting up BAR resources. Add barmap[] error checking to vfio_pci_core_disable(). - Add barmap[]/BAR index error checking to vfio_pci_core_get_iomap(), and use WARN_ON_ONCE() since the conditions truly shouldn't happen. v3: https://lore.kernel.org/kvm/20260430100340.2787446-1-mattev@meta.com/ - Remove the separate tracking of the BAR mapping versus the acquiring its resource. Errors from failing iomap vs resource reservation are ERR_PTR()-elcoded into barmap[bar]. - Remove the separate test helper, and add vfio_pci_core_get_iomap(). This gets the iomap base or is used check for error/failure to acquire the resource. Added comments at call sites explaining whether they want to just ensure the resource is reserved versus actually use the mapping. v2: https://lore.kernel.org/kvm/20260423182517.2286030-1-mattev@meta.com/ - Don't fail if resources can't be requested or iomapped, even for valid BARs, as this would change the userspace-observable error behaviour. Specifically, if there was an issue with one particular BAR which happened to never be used, then userspace would never encounter an error for it. Track iomap and resource-acquisition status per BAR. - Break out the checks for resource success from those for iomap success, in the form of the two new helpers. - Third patch to add the check to VFIO DMABUF export, because init-time requests can now fail. v1: https://lore.kernel.org/kvm/20260421174143.3883579-1-mattev@meta.com/ Matt Evans (3): vfio/pci: Set up BAR resources and maps in vfio_pci_core_enable() vfio/pci: Check BAR resources before exporting a DMABUF vfio/pci: Replace vfio_pci_core_setup_barmap() with vfio_pci_core_get_iomap() drivers/vfio/pci/nvgrace-gpu/main.c | 20 +++++++----- drivers/vfio/pci/vfio_pci_core.c | 48 ++++++++++++++++++++++++----- drivers/vfio/pci/vfio_pci_dmabuf.c | 6 ++-- drivers/vfio/pci/vfio_pci_rdwr.c | 42 +++++-------------------- drivers/vfio/pci/virtio/legacy_io.c | 13 ++++---- include/linux/vfio_pci_core.h | 20 +++++++++++- 6 files changed, 91 insertions(+), 58 deletions(-) -- 2.47.3