Matthew Rosato 2b48f52f2b vfio: fix deadlock between group lock and kvm lock ... After 51cdc8bc12, we have another deadlock scenario between the kvm->lock and the vfio group_lock with two different codepaths acquiring the locks in different order. Specifically in vfio_open_device, vfio holds the vfio group_lock when issuing device->ops->open_device but some drivers (like vfio-ap) need to acquire kvm->lock during their open_device routine; Meanwhile, kvm_vfio_release will acquire the kvm->lock first before calling vfio_file_set_kvm which will acquire the vfio group_lock. To resolve this, let's remove the need for the vfio group_lock from the kvm_vfio_release codepath. This is done by introducing a new spinlock to protect modifications to the vfio group kvm pointer, and acquiring a kvm ref from within vfio while holding this spinlock, with the reference held until the last close for the device in question. Fixes: 51cdc8bc12 ("kvm/vfio: Fix potential deadlock on vfio group_lock") Reported-by: Anthony Krowiak <akrowiak@linux.ibm.com> Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> Tested-by: Tony Krowiak <akrowiak@linux.ibm.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Yi Liu <yi.l.liu@intel.com> Link: https://lore.kernel.org/r/20230203215027.151988-2-mjrosato@linux.ibm.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>		2023-02-09 11:41:25 -07:00
..
fsl-mc	vfio/fsl-mc: Use GFP_KERNEL_ACCOUNT for userspace persistent allocations	2023-01-23 11:26:30 -07:00
mdev	vfio/mdev: Use sysfs_emit() to instead of sprintf()	2023-01-30 12:16:13 -07:00
pci	vfio/mlx5: Improve the target side flow to reduce downtime	2023-01-30 12:16:15 -07:00
platform	vfio: platform: ignore missing reset if disabled at module init	2023-02-01 12:25:41 -07:00
container.c	vfio: revert "iommu driver notify callback"	2023-02-09 11:39:14 -07:00
group.c	vfio: fix deadlock between group lock and kvm lock	2023-02-09 11:41:25 -07:00
iommufd.c	vfio-iommufd: Support iommufd for emulated VFIO devices	2022-12-02 11:52:03 -04:00
iova_bitmap.c	vfio/iova_bitmap: refactor iova_bitmap_set() to better handle page boundaries	2022-12-02 10:09:25 -07:00
Kconfig	VFIO updates for v6.2-rc1	2022-12-15 13:12:15 -08:00
Makefile	VFIO updates for v6.2-rc1	2022-12-15 13:12:15 -08:00
vfio_iommu_spapr_tce.c	vfio: Move vfio_spapr_iommu_eeh_ioctl into vfio_iommu_spapr_tce.c	2022-12-05 12:04:32 -07:00
vfio_iommu_type1.c	vfio/type1: revert "implement notify callback"	2023-02-09 11:39:14 -07:00
vfio_main.c	vfio: fix deadlock between group lock and kvm lock	2023-02-09 11:41:25 -07:00
vfio.h	vfio: fix deadlock between group lock and kvm lock	2023-02-09 11:41:25 -07:00
virqfd.c	vfio: Use GFP_KERNEL_ACCOUNT for userspace persistent allocations	2023-01-23 11:26:29 -07:00