From: Brett Creeley brett.creeley@amd.com
stable inclusion from stable-v6.6.5 commit 72654bc1d404e05ab7e7c26cfbc966f5cd63288b category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8N21P
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ Upstream commit ae2667cd8a479bb5abd6e24c12fcc9ef5bc06d75 ]
The driver could possibly sleep while in atomic context resulting in the following call trace while CONFIG_DEBUG_ATOMIC_SLEEP=y is set:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2817, name: bash preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 Call Trace: <TASK> dump_stack_lvl+0x36/0x50 __might_resched+0x123/0x170 mutex_lock+0x1e/0x50 pds_vfio_put_lm_file+0x1e/0xa0 [pds_vfio_pci] pds_vfio_put_save_file+0x19/0x30 [pds_vfio_pci] pds_vfio_state_mutex_unlock+0x2e/0x80 [pds_vfio_pci] pci_reset_function+0x4b/0x70 reset_store+0x5b/0xa0 kernfs_fop_write_iter+0x137/0x1d0 vfs_write+0x2de/0x410 ksys_write+0x5d/0xd0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
This can happen if pds_vfio_put_restore_file() and/or pds_vfio_put_save_file() grab the mutex_lock(&lm_file->lock) while the spin_lock(&pds_vfio->reset_lock) is held, which can happen during while calling pds_vfio_state_mutex_unlock().
Fix this by changing the reset_lock to reset_mutex so there are no such conerns. Also, make sure to destroy the reset_mutex in the driver specific VFIO device release function.
This also fixes a spinlock bad magic BUG that was caused by not calling spinlock_init() on the reset_lock. Since, the lock is being changed to a mutex, make sure to call mutex_init() on it.
Reported-by: Dan Carpenter dan.carpenter@linaro.org Closes: https://lore.kernel.org/kvm/1f9bc27b-3de9-4891-9687-ba2820c1b390@moroto.moun... Fixes: bb500dbe2ac6 ("vfio/pds: Add VFIO live migration support") Signed-off-by: Brett Creeley brett.creeley@amd.com Reviewed-by: Shannon Nelson shannon.nelson@amd.com Link: https://lore.kernel.org/r/20231122192532.25791-3-brett.creeley@amd.com Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/vfio/pci/pds/pci_drv.c | 4 ++-- drivers/vfio/pci/pds/vfio_dev.c | 14 ++++++++------ drivers/vfio/pci/pds/vfio_dev.h | 2 +- 3 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/drivers/vfio/pci/pds/pci_drv.c b/drivers/vfio/pci/pds/pci_drv.c index ab4b5958e413..caffa1a2cf59 100644 --- a/drivers/vfio/pci/pds/pci_drv.c +++ b/drivers/vfio/pci/pds/pci_drv.c @@ -55,10 +55,10 @@ static void pds_vfio_recovery(struct pds_vfio_pci_device *pds_vfio) * VFIO_DEVICE_STATE_RUNNING. */ if (deferred_reset_needed) { - spin_lock(&pds_vfio->reset_lock); + mutex_lock(&pds_vfio->reset_mutex); pds_vfio->deferred_reset = true; pds_vfio->deferred_reset_state = VFIO_DEVICE_STATE_ERROR; - spin_unlock(&pds_vfio->reset_lock); + mutex_unlock(&pds_vfio->reset_mutex); } }
diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c index 8c9fb87b13e1..4c351c59d05a 100644 --- a/drivers/vfio/pci/pds/vfio_dev.c +++ b/drivers/vfio/pci/pds/vfio_dev.c @@ -29,7 +29,7 @@ struct pds_vfio_pci_device *pds_vfio_pci_drvdata(struct pci_dev *pdev) void pds_vfio_state_mutex_unlock(struct pds_vfio_pci_device *pds_vfio) { again: - spin_lock(&pds_vfio->reset_lock); + mutex_lock(&pds_vfio->reset_mutex); if (pds_vfio->deferred_reset) { pds_vfio->deferred_reset = false; if (pds_vfio->state == VFIO_DEVICE_STATE_ERROR) { @@ -39,23 +39,23 @@ void pds_vfio_state_mutex_unlock(struct pds_vfio_pci_device *pds_vfio) } pds_vfio->state = pds_vfio->deferred_reset_state; pds_vfio->deferred_reset_state = VFIO_DEVICE_STATE_RUNNING; - spin_unlock(&pds_vfio->reset_lock); + mutex_unlock(&pds_vfio->reset_mutex); goto again; } mutex_unlock(&pds_vfio->state_mutex); - spin_unlock(&pds_vfio->reset_lock); + mutex_unlock(&pds_vfio->reset_mutex); }
void pds_vfio_reset(struct pds_vfio_pci_device *pds_vfio) { - spin_lock(&pds_vfio->reset_lock); + mutex_lock(&pds_vfio->reset_mutex); pds_vfio->deferred_reset = true; pds_vfio->deferred_reset_state = VFIO_DEVICE_STATE_RUNNING; if (!mutex_trylock(&pds_vfio->state_mutex)) { - spin_unlock(&pds_vfio->reset_lock); + mutex_unlock(&pds_vfio->reset_mutex); return; } - spin_unlock(&pds_vfio->reset_lock); + mutex_unlock(&pds_vfio->reset_mutex); pds_vfio_state_mutex_unlock(pds_vfio); }
@@ -156,6 +156,7 @@ static int pds_vfio_init_device(struct vfio_device *vdev) pds_vfio->vf_id = vf_id;
mutex_init(&pds_vfio->state_mutex); + mutex_init(&pds_vfio->reset_mutex);
vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P; vdev->mig_ops = &pds_vfio_lm_ops; @@ -177,6 +178,7 @@ static void pds_vfio_release_device(struct vfio_device *vdev) vfio_coredev.vdev);
mutex_destroy(&pds_vfio->state_mutex); + mutex_destroy(&pds_vfio->reset_mutex); vfio_pci_core_release_dev(vdev); }
diff --git a/drivers/vfio/pci/pds/vfio_dev.h b/drivers/vfio/pci/pds/vfio_dev.h index b8f2d667608f..e7b01080a1ec 100644 --- a/drivers/vfio/pci/pds/vfio_dev.h +++ b/drivers/vfio/pci/pds/vfio_dev.h @@ -18,7 +18,7 @@ struct pds_vfio_pci_device { struct pds_vfio_dirty dirty; struct mutex state_mutex; /* protect migration state */ enum vfio_device_mig_state state; - spinlock_t reset_lock; /* protect reset_done flow */ + struct mutex reset_mutex; /* protect reset_done flow */ u8 deferred_reset; enum vfio_device_mig_state deferred_reset_state; struct notifier_block nb;