This is the way user to invoke hot-reset for the devices opened by cdev interface. User should check the flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID_OWNED in the output of VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl before doing hot-reset for cdev devices.
Suggested-by: Jason Gunthorpe <[email protected]> Signed-off-by: Jason Gunthorpe <[email protected]> Reviewed-by: Jason Gunthorpe <[email protected]> Tested-by: Yanting Jiang <[email protected]> Signed-off-by: Yi Liu <[email protected]> --- drivers/vfio/pci/vfio_pci_core.c | 68 ++++++++++++++++++++++++++------ include/uapi/linux/vfio.h | 14 +++++++ 2 files changed, 71 insertions(+), 11 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 57586be770af..7fa3f54eb855 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -185,7 +185,8 @@ static void vfio_pci_probe_mmaps(struct vfio_pci_core_device *vdev) struct vfio_pci_group_info; static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set); static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, - struct vfio_pci_group_info *groups); + struct vfio_pci_group_info *groups, + struct iommufd_ctx *iommufd_ctx); /* * INTx masking requires the ability to disable INTx signaling via PCI_COMMAND @@ -1323,8 +1324,7 @@ vfio_pci_ioctl_pci_hot_reset_groups(struct vfio_pci_core_device *vdev, if (ret) return ret; - /* Somewhere between 1 and count is OK */ - if (!array_count || array_count > count) + if (array_count > count || vfio_device_cdev_opened(&vdev->vdev)) return -EINVAL; group_fds = kcalloc(array_count, sizeof(*group_fds), GFP_KERNEL); @@ -1373,7 +1373,7 @@ vfio_pci_ioctl_pci_hot_reset_groups(struct vfio_pci_core_device *vdev, info.count = array_count; info.files = files; - ret = vfio_pci_dev_set_hot_reset(vdev->vdev.dev_set, &info); + ret = vfio_pci_dev_set_hot_reset(vdev->vdev.dev_set, &info, NULL); hot_reset_release: for (file_idx--; file_idx >= 0; file_idx--) @@ -1402,7 +1402,11 @@ static int vfio_pci_ioctl_pci_hot_reset(struct vfio_pci_core_device *vdev, else if (pci_probe_reset_bus(vdev->pdev->bus)) return -ENODEV; - return vfio_pci_ioctl_pci_hot_reset_groups(vdev, hdr.count, slot, arg); + if (hdr.count) + return vfio_pci_ioctl_pci_hot_reset_groups(vdev, hdr.count, slot, arg); + + return vfio_pci_dev_set_hot_reset(vdev->vdev.dev_set, NULL, + vfio_iommufd_physical_ictx(&vdev->vdev)); } static int vfio_pci_ioctl_ioeventfd(struct vfio_pci_core_device *vdev, @@ -2369,13 +2373,16 @@ const struct pci_error_handlers vfio_pci_core_err_handlers = { }; EXPORT_SYMBOL_GPL(vfio_pci_core_err_handlers); -static bool vfio_dev_in_groups(struct vfio_pci_core_device *vdev, +static bool vfio_dev_in_groups(struct vfio_device *vdev, struct vfio_pci_group_info *groups) { unsigned int i; + if (!groups) + return false; + for (i = 0; i < groups->count; i++) - if (vfio_file_has_dev(groups->files[i], &vdev->vdev)) + if (vfio_file_has_dev(groups->files[i], vdev)) return true; return false; } @@ -2447,13 +2454,37 @@ static int vfio_pci_dev_set_pm_runtime_get(struct vfio_device_set *dev_set) return ret; } +static bool vfio_device_owned(struct vfio_device *vdev, + struct vfio_pci_group_info *groups, + struct iommufd_ctx *iommufd_ctx) +{ + struct iommu_group *group; + + WARN_ON(!!groups == !!iommufd_ctx); + + if (groups) + return vfio_dev_in_groups(vdev, groups); + + if (vfio_iommufd_physical_ictx(vdev) == iommufd_ctx) + return true; + + group = iommu_group_get(vdev->dev); + if (!group) + return false; + + iommu_group_put(group); + + return iommufd_ctx_has_group(iommufd_ctx, group); +} + /* * We need to get memory_lock for each device, but devices can share mmap_lock, * therefore we need to zap and hold the vma_lock for each device, and only then * get each memory_lock. */ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, - struct vfio_pci_group_info *groups) + struct vfio_pci_group_info *groups, + struct iommufd_ctx *iommufd_ctx) { struct vfio_pci_core_device *cur_mem; struct vfio_pci_core_device *cur_vma; @@ -2484,10 +2515,25 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, list_for_each_entry(cur_vma, &dev_set->device_list, vdev.dev_set_list) { /* - * Test whether all the affected devices are contained by the - * set of groups provided by the user. + * Test whether all the affected devices can be reset by the + * user. + * + * If the user provides a set of groups, all the devices + * in the dev_set should be contained by the set of groups + * provided by the user. + * + * If the user provides a zero-length group fd array, then + * all the devices in the dev_set must be bound to the same + * iommufd_ctx as the input iommufd_ctx. If there is any + * device that has not been bound to iommufd_ctx yet, check + * if its iommu_group has any device bound to the input + * iommufd_ctx Such devices can be considered owned by + * the input iommufd_ctx as the device cannot be owned + * by another iommufd_ctx when its iommu_group is owned. + * + * Otherwise, reset is not allowed. */ - if (!vfio_dev_in_groups(cur_vma, groups)) { + if (!vfio_device_owned(&cur_vma->vdev, groups, iommufd_ctx)) { ret = -EINVAL; goto err_undo; } diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 01203215251a..24858b650562 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -686,6 +686,9 @@ enum { * Flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID_OWNED would be set when all the * affected devices are owned by the user. This flag is available only * when VFIO_PCI_HOT_RESET_FLAG_DEV_ID is set, otherwise reserved. + * When set, user could invoke VFIO_DEVICE_PCI_HOT_RESET with a zero + * length fd array on the calling device as the ownership is validated + * by iommufd_ctx. * * Return: 0 on success, -errno on failure: * -enospc = insufficient buffer, -enodev = unsupported for device. @@ -717,6 +720,17 @@ struct vfio_pci_hot_reset_info { * VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13, * struct vfio_pci_hot_reset) * + * Userspace requests hot reset for the devices it operates. Due to the + * underlying topology, multiple devices can be affected in the reset + * while some might be opened by another user. To avoid interference + * the calling user must ensure all affected devices are owned by itself. + * + * As the ownership described by VFIO_DEVICE_GET_PCI_HOT_RESET_INFO, the + * cdev opened devices must exclusively provide a zero-length fd array and + * the group opened devices must exclusively use an array of group fds for + * proof of ownership. Mixed access to devices between cdev and legacy + * groups are not supported by this interface. + * * Return: 0 on success, -errno on failure. */ struct vfio_pci_hot_reset { -- 2.34.1
