On 5/20/22 9:56 AM, Tony Krowiak wrote:
On 5/19/22 2:33 PM, Matthew Rosato wrote:
Rather than relying on a notifier for associating the KVM with
the group, let's assume that the association has already been
made prior to device_open. The first time a device is opened
associate the group KVM with the device.
This fixes a user-triggerable oops in GVT.
Reviewed-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gvt/gtt.c | 4 +-
drivers/gpu/drm/i915/gvt/gvt.h | 3 -
drivers/gpu/drm/i915/gvt/kvmgt.c | 82 ++++++--------------------
drivers/s390/crypto/vfio_ap_ops.c | 35 ++---------
drivers/s390/crypto/vfio_ap_private.h | 3 -
drivers/vfio/vfio.c | 83 ++++++++++-----------------
include/linux/vfio.h | 6 +-
7 files changed, 57 insertions(+), 159 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c
b/drivers/s390/crypto/vfio_ap_ops.c
index e8914024f5b1..a7d2a95796d3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1284,25 +1284,6 @@ static void vfio_ap_mdev_unset_kvm(struct
ap_matrix_mdev *matrix_mdev)
}
}
-static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
- unsigned long action, void *data)
-{
- int notify_rc = NOTIFY_OK;
- struct ap_matrix_mdev *matrix_mdev;
-
- if (action != VFIO_GROUP_NOTIFY_SET_KVM)
- return NOTIFY_OK;
-
- matrix_mdev = container_of(nb, struct ap_matrix_mdev,
group_notifier);
-
- if (!data)
- vfio_ap_mdev_unset_kvm(matrix_mdev);
- else if (vfio_ap_mdev_set_kvm(matrix_mdev, data))
- notify_rc = NOTIFY_DONE;
-
- return notify_rc;
-}
-
static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
{
struct device *dev;
@@ -1402,11 +1383,10 @@ static int vfio_ap_mdev_open_device(struct
vfio_device *vdev)
unsigned long events;
int ret;
- matrix_mdev->group_notifier.notifier_call =
vfio_ap_mdev_group_notifier;
- events = VFIO_GROUP_NOTIFY_SET_KVM;
+ if (!vdev->kvm)
+ return -EINVAL;
- ret = vfio_register_notifier(vdev, VFIO_GROUP_NOTIFY, &events,
- &matrix_mdev->group_notifier);
+ ret = vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm);
if (ret)
return ret;
I'm sorry I didn't see this with my last review, but maybe move the call
to vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm) after the successful
registration of the IOMMU notifier? This way you won't be plugging AP
queues
into the guest only to remove them if the registration fails.
This is a pretty edge error case, and the
vfio_ap_mdev_unset_kvm(matrix_mdev) call at err_kvm should do the proper
cleanup, right? I guess I'm wondering if it's really any different than
the prior code which would have registered the VFIO_GROUP_NOTIFY_SET_KVM
first, which would have immediately triggered the notifier since the KVM
was already registered to the group, meaning it would haved called
vfio_ap_mdev_group_notifier->vfio_ap_mdev_set_kvm anyway (see
vfio_register_group_notifier, the "The attaching of kvm and vfio_group
might already happen..." comment)
@@ -1415,12 +1395,11 @@ static int vfio_ap_mdev_open_device(struct
vfio_device *vdev)
ret = vfio_register_notifier(vdev, VFIO_IOMMU_NOTIFY, &events,
&matrix_mdev->iommu_notifier);
if (ret)
- goto out_unregister_group;
+ goto err_kvm;
return 0;
-out_unregister_group:
- vfio_unregister_notifier(vdev, VFIO_GROUP_NOTIFY,
- &matrix_mdev->group_notifier);
+err_kvm:
+ vfio_ap_mdev_unset_kvm(matrix_mdev);
return ret;
}
