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[2001:8b0:8b6:13d4:102e:f2af:e074:5cde]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48e642f8d32sm369175e9.25.2026.05.07.09.56.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 May 2026 09:56:12 -0700 (PDT) Message-ID: <7d370a5d-3730-42f0-8656-14ad9c0da682@meta.com> Date: Thu, 7 May 2026 17:56:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/9] vfio/pci: Provide a user-facing name for BAR mappings Content-Language: en-GB To: Alex Williamson Cc: Leon Romanovsky , Jason Gunthorpe , Alex Mastro , =?UTF-8?Q?Christian_K=C3=B6nig?= , Mahmoud Adam , David Matlack , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Sumit Semwal , Kevin Tian , Ankit Agrawal , Pranjal Shrivastava , Alistair Popple , Vivek Kasireddy , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org References: <20260416131815.2729131-1-mattev@meta.com> <20260416131815.2729131-6-mattev@meta.com> <20260501164430.5d3ea683@shazbot.org> From: Matt Evans In-Reply-To: <20260501164430.5d3ea683@shazbot.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: oIGh_f093UE_fY09MmXyVu8_krwutieh X-Proofpoint-GUID: oIGh_f093UE_fY09MmXyVu8_krwutieh X-Authority-Analysis: v=2.4 cv=G+4s1dk5 c=1 sm=1 tr=0 ts=69fcc42f cx=c_pps a=Ech0Gv1thIkdqUNjVc2Ehg==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=4h92JMTCafKA-fb_NiOh:22 a=VwQbUJbxAAAA:8 a=VabnemYjAAAA:8 a=L20xLjZDwgROH_O_AugA:9 a=QEXdDO2ut3YA:10 a=cZgK7WzY9ta9U-6s7oqD:22 a=gKebqoRLp9LExxC7YDUY:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA3MDE3MCBTYWx0ZWRfX2u/U+81Cm8H9 iJjLUd2Ko3V1BIjUO+wSSit+EC2R4ZgNNIwutoq7AcJCw/m5wqi59oZTfuhAXiDPAh844grojpJ I+kxY+n+HSQAO370JzJW4lE1eVCzSbHsePtO29P2Zk1AeKnkBo7oQ6annM/Ox/K/2BN3BC5eQzS K4pjErqWQnlnMkIJ+pV7mXzZpZqljUNCUQiyumPwfvXeaoeZa4VrGpQzy2l9NyjC3aZptuJrm6a C2DOQxka7zQhIHrxTeqJSk7ELRLbU1yhmIco7L8ojFsaOsRCFgr5BV82Kz4p0envBQhbpBcDl/D gZDSCgUSslBTNbGA2Ih6Dp7chdqaKkUQdbHN2VY/8L0eh+iWN+nS+vE0loe8QmlSbEIQW+ZnrMI k+xKwChT5w8Jai9w0zqCC4QCSKR5obPYGmlDMauJdPxGqRyNZDs3jgnH/TNKHjEzz+mRGBOAIah bOLpgSntVYh0bi0R/bw== 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=2026-05-07_02,2026-05-06_01,2025-10-01_01 Hi Alex, On 01/05/2026 23:44, Alex Williamson wrote: > > On Thu, 16 Apr 2026 06:17:48 -0700 > Matt Evans wrote: > >> Since converting BAR mmap()s to using DMABUFs, we lose the original >> device path in /proc//maps, lsof, etc. Generate a debug-oriented >> synthetic 'filename' based on the cdev, plus BDF, plus resource index. >> >> This applies only to BAR mappings via the VFIO device fd, as >> explicitly-exported DMABUFs are named by userspace via the >> DMA_BUF_SET_NAME ioctl. >> >> Signed-off-by: Matt Evans >> --- >> drivers/vfio/pci/vfio_pci_dmabuf.c | 27 +++++++++++++++++++++++++-- >> 1 file changed, 25 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c >> index a12432825e5e..04c7733fe712 100644 >> --- a/drivers/vfio/pci/vfio_pci_dmabuf.c >> +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c >> @@ -4,6 +4,7 @@ >> #include >> #include >> #include >> +#include >> >> #include "vfio_pci_priv.h" >> >> @@ -467,6 +468,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, >> { >> struct vfio_pci_dma_buf *priv; >> const unsigned int nr_ranges = 1; >> + char *bufname; >> int ret; >> >> priv = kzalloc_obj(*priv); >> @@ -479,6 +481,20 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, >> goto err_free_priv; >> } >> >> + bufname = kzalloc(DMA_BUF_NAME_LEN, GFP_KERNEL); >> + if (!bufname) { >> + ret = -ENOMEM; >> + goto err_free_phys; >> + } >> + >> + /* >> + * Maximum size of the friendly debug name is >> + * vfio1234567890:ffff:ff:3f.7-9 = 30, which fits within >> + * DMA_BUF_NAME_LEN. >> + */ >> + snprintf(bufname, DMA_BUF_NAME_LEN, "%s:%s/%x", >> + dev_name(&vdev->vdev.device), pci_name(vdev->pdev), res_index); > > Comment suggests 9 is the max res_index that can be printed, but mmap > only directly supports standard BARs 0-5. Comment also uses a '-' > while the code uses a '/'. Thanks, Right you are. Fixed, but, since... https://lore.kernel.org/kvm/52162da4-e1cc-4f90-a95a-218d6089cd71@meta.com/ ...I'm keeping the resource index encoded in the vm_pgoffs and as that's in /proc//maps it doesn't need to be in the name. I.e., an example mapping of BAR 2 looks like: ffffa9330000-ffffad300000 rw-s 20000030000 00:0b 12 /dmabuf:vfio0:0000:00:03.0 Thanks, Matt