diff mbox series

[v3,vfio,3/3] pds/vfio: Fix possible sleep while in atomic context

Message ID 20231027223651.36047-4-brett.creeley@amd.com (mailing list archive)
State New, archived
Headers show
Series pds/vfio: Fixes for locking bugs | expand

Commit Message

Brett Creeley Oct. 27, 2023, 10:36 p.m. UTC 
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.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/kvm/1f9bc27b-3de9-4891-9687-ba2820c1b390@moroto.mountain/
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
---
 drivers/vfio/pci/pds/pci_drv.c  |  4 ++--
 drivers/vfio/pci/pds/vfio_dev.c | 15 ++++++++-------
 drivers/vfio/pci/pds/vfio_dev.h |  2 +-
 3 files changed, 11 insertions(+), 10 deletions(-)

Comments

Tian, Kevin Oct. 31, 2023, 6:14 a.m. UTC | #1 
> From: Brett Creeley <brett.creeley@amd.com>
> Sent: Saturday, October 28, 2023 6:37 AM
> 
> 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.
> 
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/kvm/1f9bc27b-3de9-4891-9687-
> ba2820c1b390@moroto.mountain/
> Signed-off-by: Brett Creeley <brett.creeley@amd.com>
> Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>

better change all three drivers together...
diff mbox series

Patch

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 306b1c25f016..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);
 }
 
@@ -156,7 +156,7 @@  static int pds_vfio_init_device(struct vfio_device *vdev)
 	pds_vfio->vf_id = vf_id;
 
 	mutex_init(&pds_vfio->state_mutex);
-	spin_lock_init(&pds_vfio->reset_lock);
+	mutex_init(&pds_vfio->reset_mutex);
 
 	vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P;
 	vdev->mig_ops = &pds_vfio_lm_ops;
@@ -178,6 +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;