[PATCH 0/4] vfio/virtio: Fix list_lock type and modernize locking

[Alex Williamson <alex.williamson@nvidia.com>]

Jinhui Guo reported a mismatched spin_lock()/spin_unlock_irq() pair
in virtiovf_read_device_context_chunk() where spin_unlock_irq() would
unconditionally enable interrupts despite spin_lock() never having
disabled them.  On closer inspection, the list_lock spinlock with IRQ
disabling was copied from the mlx5 variant driver where a hardirq
completion callback justifies it, but the virtio driver has no
interrupt context usage of list_lock.  Patch 1 converts list_lock to
a mutex, fixing the mismatch and aligning with peer vfio-pci variant
drivers.                                                                                                                                                    
Patch 2 converts the list_lock acquisitions to guard()/scoped_guard()
where the lock scope aligns naturally with function or block scope.

Patches 3 and 4 extend the same guard() conversion to the remaining
two mutexes in the driver (migf->lock and bar_mutex).  These are
relatively independent of the list_lock fix but complete the
conversion across the driver.  Thanks,

Alex

Alex Williamson (4):
  vfio/virtio: Convert list_lock from spinlock to mutex
  vfio/virtio: Use guard() for list_lock where applicable
  vfio/virtio: Use guard() for migf->lock where applicable
  vfio/virtio: Use guard() for bar_mutex in legacy I/O

 drivers/vfio/pci/virtio/common.h    |  2 +-
 drivers/vfio/pci/virtio/legacy_io.c | 17 +++---
 drivers/vfio/pci/virtio/migrate.c   | 90 ++++++++++++-----------------
 3 files changed, 46 insertions(+), 63 deletions(-)

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2.51.0