[RESEND PATCH v8 08/11] vfio: Remove use of vfio_group_viable()

Lu Baolu
2022-04-18T00:53:05Z

As DMA ownership is claimed for the iommu group when a VFIO group is
added to a VFIO container, the VFIO group viability is guaranteed as long
as group->container_users > 0. Remove those unnecessary group viability
checks which are only hit when group->container_users is not zero.

The only remaining reference is in GROUP_GET_STATUS, which could be called
at any time when group fd is valid. Here we just replace the
vfio_group_viable() by directly calling IOMMU core to get viability status.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/vfio.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 56e741cbccce..8a9347f732a5 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1313,12 +1313,6 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd)
return ret;
}

-static bool vfio_group_viable(struct vfio_group *group)
-{
- return (iommu_group_for_each_dev(group->iommu_group,
- group, vfio_dev_viable) == 0);
-}
-
static int vfio_group_add_container_user(struct vfio_group *group)
{
if (!atomic_inc_not_zero(&group->container_users))
@@ -1328,7 +1322,7 @@ static int vfio_group_add_container_user(struct vfio_group *group)
atomic_dec(&group->container_users);
return -EPERM;
}
- if (!group->container->iommu_driver || !vfio_group_viable(group)) {
+ if (!group->container->iommu_driver) {
atomic_dec(&group->container_users);
return -EINVAL;
}
@@ -1346,7 +1340,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
int ret = 0;

if (0 == atomic_read(&group->container_users) ||
- !group->container->iommu_driver || !vfio_group_viable(group))
+ !group->container->iommu_driver)
return -EINVAL;

if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
@@ -1438,11 +1432,11 @@ static long vfio_group_fops_unl_ioctl(struct file *filep,

status.flags = 0;

- if (vfio_group_viable(group))
- status.flags |= VFIO_GROUP_FLAGS_VIABLE;
-
if (group->container)
- status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET;
+ status.flags |= VFIO_GROUP_FLAGS_CONTAINER_SET |
+ VFIO_GROUP_FLAGS_VIABLE;
+ else if (!iommu_group_dma_owner_claimed(group->iommu_group))
+ status.flags |= VFIO_GROUP_FLAGS_VIABLE;

if (copy_to_user((void __user *)arg, &status, minsz))
return -EFAULT;
--
2.25.1