Commit 71791b92 authored by Yi Liu's avatar Yi Liu Committed by Alex Williamson
Browse files

vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET 



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: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Tested-by: default avatarYanting Jiang <yanting.jiang@intel.com>
Tested-by: default avatarZhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarYi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20230718105542.4138-11-yi.l.liu@intel.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent b56b7aab

drivers/vfio/pci/vfio_pci_core.c

+50 −11
Original line number Diff line number Diff line
@@ -181,7 +181,8 @@ 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
@@ -1329,8 +1330,7 @@ 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)

		return -EINVAL;



	group_fds = kcalloc(array_count, sizeof(*group_fds), GFP_KERNEL);
@@ -1379,7 +1379,7 @@ 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--)
@@ -1402,13 +1402,21 @@ static int vfio_pci_ioctl_pci_hot_reset(struct vfio_pci_core_device *vdev, 
	if (hdr.argsz < minsz || hdr.flags)

		return -EINVAL;



	/* zero-length array is only for cdev opened devices */

	if (!!hdr.count == vfio_device_cdev_opened(&vdev->vdev))

		return -EINVAL;



	/* Can we do a slot or bus reset or neither? */

	if (!pci_probe_reset_slot(vdev->pdev->slot))

		slot = true;

	else if (pci_probe_reset_bus(vdev->pdev->bus))

		return -ENODEV;



	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_device_ictx(&vdev->vdev));

}



static int vfio_pci_ioctl_ioeventfd(struct vfio_pci_core_device *vdev,
@@ -2376,13 +2384,16 @@ 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;

}
@@ -2458,7 +2469,8 @@ static int vfio_pci_dev_set_pm_runtime_get(struct vfio_device_set *dev_set) 
 * 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;
@@ -2488,11 +2500,38 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, 
		goto err_unlock;



	list_for_each_entry(cur_vma, &dev_set->device_list, vdev.dev_set_list) {

		bool owned;



		/*

		 * 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 called from a group opened device and 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 called from a cdev opened device and the user provides

		 * a zero-length array, 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 any

		 * 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 (iommufd_ctx) {

			int devid = vfio_iommufd_get_dev_id(&cur_vma->vdev,

							    iommufd_ctx);



			owned = (devid > 0 || devid == -ENOENT);

		} else {

			owned = vfio_dev_in_groups(&cur_vma->vdev, groups);

		}



		if (!owned) {

			ret = -EINVAL;

			goto err_undo;

		}

include/uapi/linux/vfio.h

+21 −0
Original line number Diff line number Diff line
@@ -717,6 +717,9 @@ enum { 
 *	  affected devices are represented in the dev_set and also owned by

 *	  the user.  This flag is available only when

 *	  flag 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.
@@ -748,6 +751,24 @@ struct vfio_pci_hot_reset_info { 
 * VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13,

 *				    struct vfio_pci_hot_reset)

 *

 * A PCI hot reset results in either a bus or slot reset which may affect

 * other devices sharing the bus/slot.  The calling user must have

 * ownership of the full set of affected devices as determined by the

 * VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl.

 *

 * When called on a device file descriptor acquired through the vfio

 * group interface, the user is required to provide proof of ownership

 * of those affected devices via the group_fds array in struct

 * vfio_pci_hot_reset.

 *

 * When called on a direct cdev opened vfio device, the flags field of

 * struct vfio_pci_hot_reset_info reports the ownership status of the

 * affected devices and this ioctl must be called with an empty group_fds

 * array.  See above INFO ioctl definition for ownership requirements.

 *

 * Mixed usage of legacy groups and cdevs across the set of affected

 * devices is not supported.

 *

 * Return: 0 on success, -errno on failure.

 */

struct vfio_pci_hot_reset {