vfio: Remove use of vfio_group_viable()

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>
Link: https://lore.kernel.org/r/20220418005000.897664-9-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 56e741c..8a9347f 100644 (file)
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1313,12 +1313,6 @@ unlock_out:
        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;