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Mon, 29 Sep 2025 14:17:52 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFTF4nahZRRX2gicTqxhxWdWKeUzRDCgsQQuCRfxHGJ4HNrczL75firr5hrFe4LKeaKRuPCNA== X-Received: by 2002:a05:6e02:1523:b0:425:9068:4ff with SMTP id e9e14a558f8ab-425955c8eb5mr97782155ab.1.1759180672251; Mon, 29 Sep 2025 14:17:52 -0700 (PDT) Received: from redhat.com ([38.15.36.11]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-425c05476fasm62141985ab.43.2025.09.29.14.17.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 14:17:51 -0700 (PDT) Date: Mon, 29 Sep 2025 15:17:49 -0600 From: Alex Williamson To: Leon Romanovsky Cc: Leon Romanovsky , Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , Christian =?UTF-8?B?S8O2bmln?= , 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 10/10] vfio/pci: Add dma-buf export support for MMIO regions Message-ID: <20250929151749.2007b192.alex.williamson@redhat.com> In-Reply-To: <53f3ea1947919a5e657b4f83e74ca53aa45814d4.1759070796.git.leon@kernel.org> References: <53f3ea1947919a5e657b4f83e74ca53aa45814d4.1759070796.git.leon@kernel.org> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 28 Sep 2025 17:50:20 +0300 Leon Romanovsky wrote: > +static int validate_dmabuf_input(struct vfio_pci_core_device *vdev, > + struct vfio_device_feature_dma_buf *dma_buf, > + struct vfio_region_dma_range *dma_ranges, > + struct p2pdma_provider **provider) > +{ > + struct pci_dev *pdev = vdev->pdev; > + u32 bar = dma_buf->region_index; > + resource_size_t bar_size; > + u64 sum; > + int i; > + > + if (dma_buf->flags) > + return -EINVAL; > + /* > + * For PCI the region_index is the BAR number like everything else. > + */ > + if (bar >= VFIO_PCI_ROM_REGION_INDEX) > + return -ENODEV; > + > + *provider = pcim_p2pdma_provider(pdev, bar); > + if (!provider) This needs to be IS_ERR_OR_NULL() or the function needs to settle on a consistent error return value regardless of CONFIG_PCI_P2PDMA. > + return -EINVAL; > + > + bar_size = pci_resource_len(pdev, bar); We get to this feature via vfio_pci_core_ioctl_feature(), which is used by several variant drivers, some of which mangle the BAR size exposed to the user, ex. hisi_acc. I'm afraid this might actually be giving dmabuf access to a portion of the BAR that isn't exposed otherwise. > + for (i = 0; i < dma_buf->nr_ranges; i++) { > + u64 offset = dma_ranges[i].offset; > + u64 len = dma_ranges[i].length; > + > + if (!PAGE_ALIGNED(offset) || !PAGE_ALIGNED(len)) > + return -EINVAL; > + > + if (check_add_overflow(offset, len, &sum) || sum > bar_size) > + return -EINVAL; > + } > + > + return 0; > +} > + > +int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, > + struct vfio_device_feature_dma_buf __user *arg, > + size_t argsz) > +{ > + struct vfio_device_feature_dma_buf get_dma_buf = {}; > + struct vfio_region_dma_range *dma_ranges; > + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); > + struct p2pdma_provider *provider; > + struct vfio_pci_dma_buf *priv; > + int ret; > + > + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET, > + sizeof(get_dma_buf)); > + if (ret != 1) > + return ret; > + > + if (copy_from_user(&get_dma_buf, arg, sizeof(get_dma_buf))) > + return -EFAULT; > + > + if (!get_dma_buf.nr_ranges) > + return -EINVAL; > + > + dma_ranges = memdup_array_user(&arg->dma_ranges, get_dma_buf.nr_ranges, > + sizeof(*dma_ranges)); > + if (IS_ERR(dma_ranges)) > + return PTR_ERR(dma_ranges); > + > + ret = validate_dmabuf_input(vdev, &get_dma_buf, dma_ranges, &provider); > + if (ret) > + return ret; goto err_free_ranges; Thanks, Alex