[{"id":3681635,"web_url":"http://patchwork.ozlabs.org/comment/3681635/","msgid":"","list_archive_url":null,"date":"2026-04-23T19:04:25","subject":"Re: [PATCH v2] PCI/P2PDMA: Avoid returning a provider for\n non_mappable_bars","submitter":{"id":78856,"url":"http://patchwork.ozlabs.org/api/people/78856/","name":"Niklas Schnelle","email":"schnelle@linux.ibm.com"},"content":"On Thu, 2026-04-23 at 10:30 -0700, Matt Evans wrote:\n> Extend the checks in pcim_p2pdma_init() and pcim_p2pdma_provider() to\n> exclude functions that have pdev->non_mappable_bars set.\n> \n> Consumers such as VFIO were previously able to map these for access by\n> the CPU or P2P. Update the comment on non_mappable_bars to show it\n> refers to any access, not just userspace CPU access.\n> \n> Fixes: 372d6d1b8ae3c (\"PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation\")\n> Signed-off-by: Matt Evans \n> ---\n> \n> This arises from Alex Williamson's suggestion to test\n> non_mappable_bars when getting the provider, with discussion here:\n> \n> https://lore.kernel.org/kvm/20260415181623.1021090-1-mattev@meta.com/\n> \n> The goal was to prevent a hole where VFIO could export DMABUFs for\n> BARs marked non-mappable, and to fix for all users of the provider\n> rather than just VFIO. Alex observed that non_mappable_bars should be\n> taken to mean BARs weren't usable by the CPU _or_ peers and,\n> considering that, its comment about userspace access wasn't quite\n> right.\n> \n> == Changes ==\n> \n> v2:\n> - Also test non_mappable_bars in pcim_p2pdma_init(), as\n> otherwise pci_p2pdma_add_resource() will WARN_ON\n> pcim_p2pdma_provider() failing.\n> \n> Niklas and Logan, I didn't re-add your R-B from v1 as (splitting\n> hairs...) the code's changed.\n> \n\nMakes sense, now feel free to re-add ;)\n\nReviewed-by: Niklas Schnelle \n\nThanks,\nNiklas","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256\n header.s=pp1 header.b=mWit9iXd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c09:e001:a7::12fc:5321; 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charset=\"UTF-8\"","Content-Transfer-Encoding":"quoted-printable","Date":"Thu, 23 Apr 2026 21:04:25 +0200","Precedence":"bulk","X-Mailing-List":"linux-pci@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","User-Agent":"Evolution 3.58.3 (3.58.3-1.fc43) ","X-TM-AS-GCONF":"00","X-Proofpoint-Reinject":"loops=2 maxloops=12","X-Proofpoint-GUID":"4AgvFRtSjGI8rQmNSXteRbPifdrTHJvy","X-Proofpoint-Spam-Details-Enc":"AW1haW4tMjYwNDIzMDE4MyBTYWx0ZWRfX1X8fbM12GOpD\n 231eTKlsu9csx89VGXcVyZSOyOXky8tfWW0PiGJQsg66EmcNa2SCImyvzheV33ga61yusfKH/L7\n yHcpLqgM+QXTRRpXGemIe/Jcjkl6sFbdBJ4HxMQ2B/BfuwkucBTMEEGjZSCyEij4GnADFaTFL5p\n ux+8bl5vro3aLwGnnxkVGqvBsmtBmvi4Ip+MLBAB2hydKYJf6H93l8QrlznDifk9wM3WwfWko37\n vJrv1LjY51xxEda52zK6a+in6QOHJP1e1sCY/GT+DF1usgoluBEtYUa7UQrW7C6SKCmqNLY67wk\n EpJK6ekgjBHt6Ew4dpZdH2JzVssaSE82+GWxLWXTNltDzqA18wMWSRxot0Tq18d0C5YTRPM0o/M\n Oon7wovhqx3ub1+emyL6JhDunBu8LMfVldqbS/IKhEUZxubLLLJrQwDg2vFVkStMPhXCY3QFzza\n 4J1Uw8Uau1Q0pQ2TsoQ==","X-Authority-Analysis":"v=2.4 cv=a6kAM0SF c=1 sm=1 tr=0 ts=69ea6d79 cx=c_pps\n a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17\n a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22\n a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8\n a=VabnemYjAAAA:8 a=VnNF1IyMAAAA:8 a=teCjjoZnVze8JZkblVgA:9 a=QEXdDO2ut3YA:10\n a=gKebqoRLp9LExxC7YDUY:22","X-Proofpoint-ORIG-GUID":"LPm2vYsAhkVaGLjFsbCFuV1L7ANeR68m","X-Proofpoint-Virus-Version":"vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-04-23_03,2026-04-21_02,2025-10-01_01","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n malwarescore=0 suspectscore=0 spamscore=0 adultscore=0 bulkscore=0\n lowpriorityscore=0 impostorscore=0 clxscore=1015 phishscore=0\n priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc=\n route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000\n definitions=main-2604230183"}},{"id":3681654,"web_url":"http://patchwork.ozlabs.org/comment/3681654/","msgid":"<20260423134052.292e92cf@shazbot.org>","list_archive_url":null,"date":"2026-04-23T19:40:52","subject":"Re: [PATCH v2] PCI/P2PDMA: Avoid returning a provider for\n non_mappable_bars","submitter":{"id":91887,"url":"http://patchwork.ozlabs.org/api/people/91887/","name":"Alex Williamson","email":"alex@shazbot.org"},"content":"On Thu, 23 Apr 2026 10:30:51 -0700\nMatt Evans wrote:\n\n> Extend the checks in pcim_p2pdma_init() and pcim_p2pdma_provider() to\n> exclude functions that have pdev->non_mappable_bars set.\n> \n> Consumers such as VFIO were previously able to map these for access by\n> the CPU or P2P. Update the comment on non_mappable_bars to show it\n> refers to any access, not just userspace CPU access.\n> \n> Fixes: 372d6d1b8ae3c (\"PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation\")\n> Signed-off-by: Matt Evans \n> ---\n> \n> This arises from Alex Williamson's suggestion to test\n> non_mappable_bars when getting the provider, with discussion here:\n> \n> https://lore.kernel.org/kvm/20260415181623.1021090-1-mattev@meta.com/\n> \n> The goal was to prevent a hole where VFIO could export DMABUFs for\n> BARs marked non-mappable, and to fix for all users of the provider\n> rather than just VFIO. Alex observed that non_mappable_bars should be\n> taken to mean BARs weren't usable by the CPU _or_ peers and,\n> considering that, its comment about userspace access wasn't quite\n> right.\n> \n> == Changes ==\n> \n> v2:\n> - Also test non_mappable_bars in pcim_p2pdma_init(), as\n> otherwise pci_p2pdma_add_resource() will WARN_ON\n> pcim_p2pdma_provider() failing.\n> \n> Niklas and Logan, I didn't re-add your R-B from v1 as (splitting\n> hairs...) the code's changed.\n> \n> v1:\n> https://lore.kernel.org/linux-pci/20260421174351.3897842-1-mattev@meta.com/\n> \n> \n> drivers/pci/p2pdma.c | 6 +++++-\n> include/linux/pci.h | 2 +-\n> 2 files changed, 6 insertions(+), 2 deletions(-)\n> \n> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c\n> index 7c898542af8d..adb17a4f6939 100644\n> --- a/drivers/pci/p2pdma.c\n> +++ b/drivers/pci/p2pdma.c\n> @@ -262,6 +262,9 @@ int pcim_p2pdma_init(struct pci_dev *pdev)\n> \tstruct pci_p2pdma *p2p;\n> \tint i, ret;\n> \n> +\tif (pdev->non_mappable_bars)\n> +\t\treturn -EOPNOTSUPP;\n> +\n> \tp2p = rcu_dereference_protected(pdev->p2pdma, 1);\n> \tif (p2p)\n> \t\treturn 0;\n> @@ -318,7 +321,8 @@ struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar)\n> {\n> \tstruct pci_p2pdma *p2p;\n> \n> -\tif (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))\n> +\tif (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM) ||\n> +\t pdev->non_mappable_bars)\n> \t\treturn NULL;\n> \n> \tp2p = rcu_dereference_protected(pdev->p2pdma, 1);\n> diff --git a/include/linux/pci.h b/include/linux/pci.h\n> index 2c4454583c11..1e6802017d6b 100644\n> --- a/include/linux/pci.h\n> +++ b/include/linux/pci.h\n> @@ -508,7 +508,7 @@ struct pci_dev {\n> \tunsigned int\tno_command_memory:1;\t/* No PCI_COMMAND_MEMORY */\n> \tunsigned int\trom_bar_overlap:1;\t/* ROM BAR disable broken */\n> \tunsigned int\trom_attr_enabled:1;\t/* Display of ROM attribute enabled? */\n> -\tunsigned int\tnon_mappable_bars:1;\t/* BARs can't be mapped to user-space */\n> +\tunsigned int\tnon_mappable_bars:1;\t/* BARs can't be mapped by CPU or peers */\n> \tpci_dev_flags_t dev_flags;\n> \tatomic_t\tenable_cnt;\t/* pci_enable_device has been called */\n> \n\nReviewed-by: Alex Williamson \nSuggested-by: Alex Williamson \n\nThanks,\nAlex","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=shazbot.org header.i=@shazbot.org header.a=rsa-sha256\n header.s=fm1 header.b=bMhsBi1G;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=messagingengine.com header.i=@messagingengine.com\n header.a=rsa-sha256 header.s=fm2 header.b=tf9/upFY;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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x86_64-pc-linux-gnu)","Precedence":"bulk","X-Mailing-List":"linux-pci@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=US-ASCII","Content-Transfer-Encoding":"7bit"}},{"id":3682094,"web_url":"http://patchwork.ozlabs.org/comment/3682094/","msgid":"<20260424160823.GA11106@bhelgaas>","list_archive_url":null,"date":"2026-04-24T16:08:23","subject":"Re: [PATCH v2] PCI/P2PDMA: Avoid returning a provider for\n non_mappable_bars","submitter":{"id":67298,"url":"http://patchwork.ozlabs.org/api/people/67298/","name":"Bjorn Helgaas","email":"helgaas@kernel.org"},"content":"On Thu, Apr 23, 2026 at 10:30:51AM -0700, Matt Evans wrote:\n> Extend the checks in pcim_p2pdma_init() and pcim_p2pdma_provider() to\n> exclude functions that have pdev->non_mappable_bars set.\n> \n> Consumers such as VFIO were previously able to map these for access by\n> the CPU or P2P. Update the comment on non_mappable_bars to show it\n> refers to any access, not just userspace CPU access.\n> \n> Fixes: 372d6d1b8ae3c (\"PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation\")\n> Signed-off-by: Matt Evans \n\nApplied to pci/p2pdma for v7.2, thanks! Will be rebased after\nv7.1-rc1.\n\n> ---\n> \n> This arises from Alex Williamson's suggestion to test\n> non_mappable_bars when getting the provider, with discussion here:\n> \n> https://lore.kernel.org/kvm/20260415181623.1021090-1-mattev@meta.com/\n> \n> The goal was to prevent a hole where VFIO could export DMABUFs for\n> BARs marked non-mappable, and to fix for all users of the provider\n> rather than just VFIO. Alex observed that non_mappable_bars should be\n> taken to mean BARs weren't usable by the CPU _or_ peers and,\n> considering that, its comment about userspace access wasn't quite\n> right.\n> \n> == Changes ==\n> \n> v2:\n> - Also test non_mappable_bars in pcim_p2pdma_init(), as\n> otherwise pci_p2pdma_add_resource() will WARN_ON\n> pcim_p2pdma_provider() failing.\n> \n> Niklas and Logan, I didn't re-add your R-B from v1 as (splitting\n> hairs...) the code's changed.\n> \n> v1:\n> https://lore.kernel.org/linux-pci/20260421174351.3897842-1-mattev@meta.com/\n> \n> \n> drivers/pci/p2pdma.c | 6 +++++-\n> include/linux/pci.h | 2 +-\n> 2 files changed, 6 insertions(+), 2 deletions(-)\n> \n> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c\n> index 7c898542af8d..adb17a4f6939 100644\n> --- a/drivers/pci/p2pdma.c\n> +++ b/drivers/pci/p2pdma.c\n> @@ -262,6 +262,9 @@ int pcim_p2pdma_init(struct pci_dev *pdev)\n> \tstruct pci_p2pdma *p2p;\n> \tint i, ret;\n> \n> +\tif (pdev->non_mappable_bars)\n> +\t\treturn -EOPNOTSUPP;\n> +\n> \tp2p = rcu_dereference_protected(pdev->p2pdma, 1);\n> \tif (p2p)\n> \t\treturn 0;\n> @@ -318,7 +321,8 @@ struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar)\n> {\n> \tstruct pci_p2pdma *p2p;\n> \n> -\tif (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))\n> +\tif (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM) ||\n> +\t pdev->non_mappable_bars)\n> \t\treturn NULL;\n> \n> \tp2p = rcu_dereference_protected(pdev->p2pdma, 1);\n> diff --git a/include/linux/pci.h b/include/linux/pci.h\n> index 2c4454583c11..1e6802017d6b 100644\n> --- a/include/linux/pci.h\n> +++ b/include/linux/pci.h\n> @@ -508,7 +508,7 @@ struct pci_dev {\n> \tunsigned int\tno_command_memory:1;\t/* No PCI_COMMAND_MEMORY */\n> \tunsigned int\trom_bar_overlap:1;\t/* ROM BAR disable broken */\n> \tunsigned int\trom_attr_enabled:1;\t/* Display of ROM attribute enabled? */\n> -\tunsigned int\tnon_mappable_bars:1;\t/* BARs can't be mapped to user-space */\n> +\tunsigned int\tnon_mappable_bars:1;\t/* BARs can't be mapped by CPU or peers */\n> \tpci_dev_flags_t dev_flags;\n> \tatomic_t\tenable_cnt;\t/* pci_enable_device has been called */\n> \n> -- \n> 2.47.3\n>","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=hCvGPHa5;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; helo=sea.lore.kernel.org;\n envelope-from=linux-pci+bounces-53147-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=\"hCvGPHa5\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=10.30.226.201"],"Received":["from sea.lore.kernel.org (sea.lore.kernel.org [172.234.253.10])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g2Hw72kWFz1yD5\n\tfor ; Sat, 25 Apr 2026 02:09:27 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sea.lore.kernel.org (Postfix) with ESMTP id 8547830097F1\n\tfor ; Fri, 24 Apr 2026 16:08:25 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id D9A803DC4BD;\n\tFri, 24 Apr 2026 16:08:24 +0000 (UTC)","from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org\n [10.30.226.201])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id B72F53DBD57;\n\tFri, 24 Apr 2026 16:08:24 +0000 (UTC)","by smtp.kernel.org (Postfix) with ESMTPSA id 42CA8C19425;\n\tFri, 24 Apr 2026 16:08:24 +0000 (UTC)"],"ARC-Seal":"i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777046904; cv=none;\n b=noNIvHZPiX0GCG38FPJqRrYeyNFEo5ykyzGuJJZ1OondCFTkGp0cPeGMAVGpU8+VmtNWRLj9WaxAFhNT41KN17DO3s8qpMjquH++aYFnOQzwu6QdHugdP1Dj5xa+eFHmQu7EgBu/3VtI1m/63suxb0xNIRheEouhj0nAe46rpfU=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777046904; c=relaxed/simple;\n\tbh=hGC9jnHTZV5EtsFQpRo2fI3KRRoZIvzL+Z9bPIl/ziI=;\n\th=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type:\n\t Content-Disposition:In-Reply-To;\n b=TboDOU4cjv/WYgudDczIdaL+hLBtehj2ByZIIP7xBGt7bAD0iJO/QjreYpFXeMgssMjP/NGhI2gmJBmZU5/Ld8tvWXqMeD/yeHzMmIvljyKhx9U411lXSPXnXAyxsJiUp5Roo7oZrPCbWM1iSeYeLuKBpxOJjUjEGciFF5gWPQE=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=hCvGPHa5; arc=none smtp.client-ip=10.30.226.201","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777046904;\n\tbh=hGC9jnHTZV5EtsFQpRo2fI3KRRoZIvzL+Z9bPIl/ziI=;\n\th=Date:From:To:Cc:Subject:In-Reply-To:From;\n\tb=hCvGPHa5RcLZR9Zd3hpo0lZutgG3asKWUUJvamKu41u/Fjo4LbsrmW7UoHwRiDHu+\n\t hzFxLRZmfgyPkd83sux0ZbVwlh4LCIsrOb03UzLJ53B4xvrtD3svOB9RUh0z8aYLdY\n\t hx5OC0/J6ZsF9xhIA7vOoTENcGmtyU6t3UtMeB6s/9RnYLhRgmL6Wu9YNZZsmc6Dsw\n\t of2PZtPnjCO6c5cCbASofpSZlR2kQ5OXOV/tIaMoBz0qiHISJnssAWACJ228pNvHl1\n\t K+ZPYNQiHETg7GHsz6vlHilobXpQmTvzcaoH78HfFJ3qcOwqla9HCDoVljUXKS9QPg\n\t psseq8vPM7IYw==","Date":"Fri, 24 Apr 2026 11:08:23 -0500","From":"Bjorn Helgaas ","To":"Matt Evans ","Cc":"Bjorn Helgaas ,\n\tLogan Gunthorpe ,\n\tAnkit Agrawal ,\n\tLeon Romanovsky ,\n\tAlex Williamson ,\n\tNiklas Schnelle , linux-pci@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org","Subject":"Re: [PATCH v2] PCI/P2PDMA: Avoid returning a provider for\n non_mappable_bars","Message-ID":"<20260424160823.GA11106@bhelgaas>","Precedence":"bulk","X-Mailing-List":"linux-pci@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260423173051.1999679-1-mattev@meta.com>"}}]