On Mon, Sep 29, 2025 at 03:17:49PM -0600, Alex Williamson wrote:
On Sun, 28 Sep 2025 17:50:20 +0300 Leon Romanovsky leon@kernel.org 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.
pcim_p2pdma_provider() doesn't return errors after split to _init() and _get(). The more accurate check needs to be if (!*provider) and not what is written.
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.
Doe you mean that part?
1185 static int hisi_acc_vf_qm_init(struct hisi_acc_vf_core_device *hisi_acc_vdev) 1186 { ... 1204 * Also the HiSilicon ACC VF devices supported by this driver on 1205 * HiSilicon hardware platforms are integrated end point devices 1206 * and the platform lacks the capability to perform any PCIe P2P 1207 * between these devices. 1208 */ 1209 1210 vf_qm->io_base = 1211 ioremap(pci_resource_start(vf_dev, VFIO_PCI_BAR2_REGION_INDEX), 1212 pci_resource_len(vf_dev, VFIO_PCI_BAR2_REGION_INDEX)); 1213 if (!vf_qm->io_base) 1214 return -EIO; 1215
According to the comment, it doesn't support p2p and in any case we will fail that platform in vfio_pci_dma_buf_attach() by taking "default" case:
34 switch (pci_p2pdma_map_type(priv->provider, attachment->dev)) { 35 case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: 36 break; 37 case PCI_P2PDMA_MAP_BUS_ADDR: 38 /* 39 * There is no need in IOVA at all for this flow. 40 * We rely on attachment->priv == NULL as a marker 41 * for this mode. 42 */ 43 return 0; 44 default: 45 return -EINVAL; 46 } 47
- 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
Thanks, Alex