vfio-ccw: Release any channel program when releasing/removing vfio-ccw mdev

When releasing the vfio-ccw mdev, we currently do not release
any existing channel program and its pinned pages. This can
lead to the following warning:

[1038876.561565] WARNING: CPU: 2 PID: 144727 at drivers/vfio/vfio_iommu_type1.c:1494 vfio_sanity_check_pfn_list+0x40/0x70 [vfio_iommu_type1]

....

1038876.561921] Call Trace:
[1038876.561935] ([<00000009897fb870>] 0x9897fb870)
[1038876.561949]  [<000003ff8013bf62>] vfio_iommu_type1_detach_group+0xda/0x2f0 [vfio_iommu_type1]
[1038876.561965]  [<000003ff8007b634>] __vfio_group_unset_container+0x64/0x190 [vfio]
[1038876.561978]  [<000003ff8007b87e>] vfio_group_put_external_user+0x26/0x38 [vfio]
[1038876.562024]  [<000003ff806fc608>] kvm_vfio_group_put_external_user+0x40/0x60 [kvm]
[1038876.562045]  [<000003ff806fcb9e>] kvm_vfio_destroy+0x5e/0xd0 [kvm]
[1038876.562065]  [<000003ff806f63fc>] kvm_put_kvm+0x2a4/0x3d0 [kvm]
[1038876.562083]  [<000003ff806f655e>] kvm_vm_release+0x36/0x48 [kvm]
[1038876.562098]  [<00000000003c2dc4>] __fput+0x144/0x228
[1038876.562113]  [<000000000016ee82>] task_work_run+0x8a/0xd8
[1038876.562125]  [<000000000014c7a8>] do_exit+0x5d8/0xd90
[1038876.562140]  [<000000000014d084>] do_group_exit+0xc4/0xc8
[1038876.562155]  [<000000000015c046>] get_signal+0x9ae/0xa68
[1038876.562169]  [<0000000000108d66>] do_signal+0x66/0x768
[1038876.562185]  [<0000000000b9e37e>] system_call+0x1ea/0x2d8
[1038876.562195] 2 locks held by qemu-system-s39/144727:
[1038876.562205]  #0: 00000000537abaf9 (&container->group_lock){++++}, at: __vfio_group_unset_container+0x3c/0x190 [vfio]
[1038876.562230]  #1: 00000000670008b5 (&iommu->lock){+.+.}, at: vfio_iommu_type1_detach_group+0x36/0x2f0 [vfio_iommu_type1]
[1038876.562250] Last Breaking-Event-Address:
[1038876.562262]  [<000003ff8013aa24>] vfio_sanity_check_pfn_list+0x3c/0x70 [vfio_iommu_type1]
[1038876.562272] irq event stamp: 4236481
[1038876.562287] hardirqs last  enabled at (4236489): [<00000000001cee7a>] console_unlock+0x6d2/0x740
[1038876.562299] hardirqs last disabled at (4236496): [<00000000001ce87e>] console_unlock+0xd6/0x740
[1038876.562311] softirqs last  enabled at (4234162): [<0000000000b9fa1e>] __do_softirq+0x556/0x598
[1038876.562325] softirqs last disabled at (4234153): [<000000000014e4cc>] irq_exit+0xac/0x108
[1038876.562337] ---[ end trace 6c96d467b1c3ca06 ]---

Similarly we do not free the channel program when we are removing
the vfio-ccw device. Let's fix this by resetting the device and freeing
the channel program and pinned pages in the release path. For the remove
path we can just quiesce the device, since in the remove path the mediated
device is going away for good and so we don't need to do a full reset.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <ae9f20dc8873f2027f7b3c5d2aaa0bdfe06850b8.1554756534.git.alifm@linux.ibm.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 3e2802a4a43db8c71c489ceb765a783a6c6a7f31..5eb61116ca6fb2252d99ce2cc1c7ce006ea6aeb8 100644 (file)
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -134,11 +134,12 @@ static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
 
        if ((private->state != VFIO_CCW_STATE_NOT_OPER) &&
            (private->state != VFIO_CCW_STATE_STANDBY)) {
-               if (!vfio_ccw_mdev_reset(mdev))
+               if (!vfio_ccw_sch_quiesce(private->sch))
                        private->state = VFIO_CCW_STATE_STANDBY;
                /* The state will be NOT_OPER on error. */
        }
 
+       cp_free(&private->cp);
        private->mdev = NULL;
        atomic_inc(&private->avail);
 
@@ -172,6 +173,14 @@ static void vfio_ccw_mdev_release(struct mdev_device *mdev)
                dev_get_drvdata(mdev_parent_dev(mdev));
        int i;
 
+       if ((private->state != VFIO_CCW_STATE_NOT_OPER) &&
+           (private->state != VFIO_CCW_STATE_STANDBY)) {
+               if (!vfio_ccw_mdev_reset(mdev))
+                       private->state = VFIO_CCW_STATE_STANDBY;
+               /* The state will be NOT_OPER on error. */
+       }
+
+       cp_free(&private->cp);
        vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
                                 &private->nb);