This series contains fixes for locking bugs in the recently introduced
pds-vfio-pci driver. There was an initial bug reported by Dan Carpenter
at:
https://lore.kernel.org/kvm/[email protected]/
However, more locking bugs were found when looking into the previously
mentioned issue. So, all fixes are included in this series.
Brett Creeley (3):
pds/vfio: Fix spinlock bad magic BUG
pds/vfio: Fix mutex lock->magic != lock warning
pds/vfio: Fix possible sleep while in atomic context
drivers/vfio/pci/pds/vfio_dev.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--
2.17.1
The following BUG was found when running on a kernel with
CONFIG_DEBUG_MUTEXES=y set:
[ 502.794510] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
[ 502.794519] WARNING: CPU: 16 PID: 2571 at kernel/locking/mutex.c:1085 mutex_trylock+0x10d/0x120
[ 502.794537] Modules linked in: pds_vfio_pci(OE) pds_core xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nft_compat
nf_nat_tftp nf_conntrack_tftp bridge stp llc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4
nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink
intel_rapl_msr intel_rapl_common isst_if_common nfit libnvdimm x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm
crct10dif_pclmul crc32_pclmul ghash_clmulni_intel rapl mei_me ses intel_cstate ipmi_ssif sunrpc enclosure mei nvme
intel_uncore nvme_core hpwdt hpilo ioatdma acpi_tad acpi_ipmi pcspkr lpc_ich intel_pch_thermal acpi_power_meter ipmi_si xfs
libcrc32c sd_mod t10_pi crc64_rocksoft crc64 sg mgag200 drm_kms_helper drm_shmem_helper crc32c_intel serio_raw igb smartpqi
dca drm scsi_transport_sas i2c_algo_bit ionic wmi dm_mirror dm_region_hash dm_log dm_mod ipmi_devintf ipmi_msghandler
fuse [last unloaded: pds_core]
[ 502.794673] CPU: 16 PID: 2571 Comm: bash Tainted: G S OE 6.6.0-rc1-next-20230911 #1
[ 502.794676] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 01/23/2021
[ 502.794678] RIP: 0010:mutex_trylock+0x10d/0x120
[ 502.794681] Code: ff 85 c0 0f 84 40 ff ff ff 8b 3d f2 35 eb 00 85 ff 0f 85 32 ff ff ff 48 c7 c6 47 ff d3 bc 48 c7 c7 80 69 d3 bc e8 33 c7 4a ff <0f> 0b e9 18 ff ff ff b8 01 00 00 00 e9 5c ff ff ff 66 90 90 90 90
[ 502.794684] RSP: 0018:ffffabadc750fda8 EFLAGS: 00010282
[ 502.794686] RAX: 0000000000000000 RBX: ffff930000451000 RCX: 0000000000000027
[ 502.794688] RDX: 0000000000000027 RSI: ffffabadc750fca0 RDI: ffff930f7f920948
[ 502.794690] RBP: ffff930000451708 R08: 0000000000000000 R09: c0000000ffff7fff
[ 502.794692] R10: 0000000000000001 R11: ffffabadc750fc40 R12: 0000000000000000
[ 502.794694] R13: fffffffffffffff2 R14: ffffabadc750fea0 R15: ffff92ffc85dc520
[ 502.794695] FS: 00007f3d8e322740(0000) GS:ffff930f7f900000(0000) knlGS:0000000000000000
[ 502.794697] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 502.794698] CR2: 000055cc4f6d9310 CR3: 0000000109894005 CR4: 00000000007706e0
[ 502.794700] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 502.794701] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 502.794703] PKRU: 55555554
[ 502.794704] Call Trace:
[ 502.794707] <TASK>
[ 502.794710] ? __warn+0x85/0x140
[ 502.794718] ? mutex_trylock+0x10d/0x120
[ 502.794720] ? report_bug+0xfc/0x1e0
[ 502.794727] ? handle_bug+0x3f/0x70
[ 502.794732] ? exc_invalid_op+0x17/0x70
[ 502.794735] ? asm_exc_invalid_op+0x1a/0x20
[ 502.794742] ? mutex_trylock+0x10d/0x120
[ 502.794744] ? mutex_trylock+0x10d/0x120
[ 502.794748] pds_vfio_reset+0x3a/0x60 [pds_vfio_pci]
[ 502.794756] pci_reset_function+0x4b/0x70
[ 502.794763] reset_store+0x5b/0xa0
[ 502.794770] kernfs_fop_write_iter+0x137/0x1d0
[ 502.794776] vfs_write+0x2de/0x410
[ 502.794784] ksys_write+0x5d/0xd0
[ 502.794787] do_syscall_64+0x3b/0x90
[ 502.794790] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 502.794794] RIP: 0033:0x7f3d8d51fa28
[ 502.794796] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 15 4d 2a 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55
[ 502.794799] RSP: 002b:00007ffc7b6c76f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 502.794801] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f3d8d51fa28
[ 502.794803] RDX: 0000000000000002 RSI: 000055cc4f742aa0 RDI: 0000000000000001
[ 502.794804] RBP: 000055cc4f742aa0 R08: 000000000000000a R09: 00007f3d8d57fae0
[ 502.794805] R10: 000000000000000a R11: 0000000000000246 R12: 00007f3d8d7c06e0
[ 502.794807] R13: 0000000000000002 R14: 00007f3d8d7bb860 R15: 0000000000000002
[ 502.794809] </TASK>
As shown, lock->magic != lock. This is because
mutex_init(&pds_vfio->state_mutex) is called in the VFIO open path. So,
if a reset is initiated before the VFIO device is opened the mutex will
have never been initialized. Fix this by calling
mutex_init(&pds_vfio->state_mutex) in the VFIO init path.
Signed-off-by: Brett Creeley <[email protected]>
Reviewed-by: Shannon Nelson <[email protected]>
---
drivers/vfio/pci/pds/vfio_dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
index 147a543a7c39..9db5f2c8f1ea 100644
--- a/drivers/vfio/pci/pds/vfio_dev.c
+++ b/drivers/vfio/pci/pds/vfio_dev.c
@@ -155,6 +155,7 @@ 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);
vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P;
@@ -181,7 +182,6 @@ static int pds_vfio_open_device(struct vfio_device *vdev)
if (err)
return err;
- mutex_init(&pds_vfio->state_mutex);
pds_vfio->state = VFIO_DEVICE_STATE_RUNNING;
pds_vfio->deferred_reset_state = VFIO_DEVICE_STATE_RUNNING;
--
2.17.1
The following BUG was found when running on a kernel with
CONFIG_DEBUG_SPINLOCK=y set:
[ 675.116953] BUG: spinlock bad magic on CPU#2, bash/2481
[ 675.116966] lock: 0xffff8d6052a88f50, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
[ 675.116978] CPU: 2 PID: 2481 Comm: bash Tainted: G S 6.6.0-rc1-next-20230911 #1
[ 675.116986] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 01/23/2021
[ 675.116991] Call Trace:
[ 675.116997] <TASK>
[ 675.117002] dump_stack_lvl+0x36/0x50
[ 675.117014] do_raw_spin_lock+0x79/0xc0
[ 675.117032] pds_vfio_reset+0x1d/0x60 [pds_vfio_pci]
[ 675.117049] pci_reset_function+0x4b/0x70
[ 675.117061] reset_store+0x5b/0xa0
[ 675.117074] kernfs_fop_write_iter+0x137/0x1d0
[ 675.117087] vfs_write+0x2de/0x410
[ 675.117101] ksys_write+0x5d/0xd0
[ 675.117111] do_syscall_64+0x3b/0x90
[ 675.117122] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 675.117135] RIP: 0033:0x7f9ebbd1fa28
[ 675.117141] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 15 4d 2a 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55
[ 675.117148] RSP: 002b:00007ffdff410728 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 675.117156] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f9ebbd1fa28
[ 675.117161] RDX: 0000000000000002 RSI: 000055ffc5fdf7c0 RDI: 0000000000000001
[ 675.117166] RBP: 000055ffc5fdf7c0 R08: 000000000000000a R09: 00007f9ebbd7fae0
[ 675.117170] R10: 000000000000000a R11: 0000000000000246 R12: 00007f9ebbfc06e0
[ 675.117174] R13: 0000000000000002 R14: 00007f9ebbfbb860 R15: 0000000000000002
[ 675.117180] </TASK>
As shown, the .magic: 00000000, does not match the expected value. This
is because spin_lock_init() is never called for the reset_lock. Fix
this by calling spin_lock_init(&pds_vfio->reset_lock) when initializing
the device.
Signed-off-by: Brett Creeley <[email protected]>
Reviewed-by: Shannon Nelson <[email protected]>
---
drivers/vfio/pci/pds/vfio_dev.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
index b46174f5eb09..147a543a7c39 100644
--- a/drivers/vfio/pci/pds/vfio_dev.c
+++ b/drivers/vfio/pci/pds/vfio_dev.c
@@ -155,6 +155,8 @@ static int pds_vfio_init_device(struct vfio_device *vdev)
pds_vfio->vf_id = vf_id;
+ spin_lock_init(&pds_vfio->reset_lock);
+
vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P;
vdev->mig_ops = &pds_vfio_lm_ops;
vdev->log_ops = &pds_vfio_log_ops;
--
2.17.1
The driver could possibly sleep while in atomic context resulting
in the following call trace while CONFIG_DEBUG_ATOMIC_SLEEP=y is
set:
[ 227.229806] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283
[ 227.229818] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2817, name: bash
[ 227.229824] preempt_count: 1, expected: 0
[ 227.229827] RCU nest depth: 0, expected: 0
[ 227.229832] CPU: 5 PID: 2817 Comm: bash Tainted: G S OE 6.6.0-rc1-next-20230911 #1
[ 227.229839] Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 01/23/2021
[ 227.229843] Call Trace:
[ 227.229848] <TASK>
[ 227.229853] dump_stack_lvl+0x36/0x50
[ 227.229865] __might_resched+0x123/0x170
[ 227.229877] mutex_lock+0x1e/0x50
[ 227.229891] pds_vfio_put_lm_file+0x1e/0xa0 [pds_vfio_pci]
[ 227.229909] pds_vfio_put_save_file+0x19/0x30 [pds_vfio_pci]
[ 227.229923] pds_vfio_state_mutex_unlock+0x2e/0x80 [pds_vfio_pci]
[ 227.229937] pci_reset_function+0x4b/0x70
[ 227.229948] reset_store+0x5b/0xa0
[ 227.229959] kernfs_fop_write_iter+0x137/0x1d0
[ 227.229972] vfs_write+0x2de/0x410
[ 227.229986] ksys_write+0x5d/0xd0
[ 227.229996] do_syscall_64+0x3b/0x90
[ 227.230004] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 227.230017] RIP: 0033:0x7fb202b1fa28
[ 227.230023] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 15 4d 2a 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55
[ 227.230028] RSP: 002b:00007fff6915fbd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 227.230036] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fb202b1fa28
[ 227.230040] RDX: 0000000000000002 RSI: 000055f3834d5aa0 RDI: 0000000000000001
[ 227.230044] RBP: 000055f3834d5aa0 R08: 000000000000000a R09: 00007fb202b7fae0
[ 227.230047] R10: 000000000000000a R11: 0000000000000246 R12: 00007fb202dc06e0
[ 227.230050] R13: 0000000000000002 R14: 00007fb202dbb860 R15: 0000000000000002
[ 227.230056] </TASK>
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 releasing the spin_unlock(&pds_vfio->reset_lock) before
calling pds_vfio_put_restore_file() and pds_vfio_put_save_file() and
re-acquiring spin_lock(&pds_vfio->reset_lock) after the previously
mentioned functions are called to protect setting the subsequent
state/deferred reset settings.
The only possible concerns are other threads that may call
pds_vfio_put_restore_file() and/or pds_vfio_put_save_file(). However,
those paths are already protected by the state mutex_lock().
Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/kvm/[email protected]/
Signed-off-by: Brett Creeley <[email protected]>
Reviewed-by: Shannon Nelson <[email protected]>
---
drivers/vfio/pci/pds/vfio_dev.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
index 9db5f2c8f1ea..6e664cb05dd1 100644
--- a/drivers/vfio/pci/pds/vfio_dev.c
+++ b/drivers/vfio/pci/pds/vfio_dev.c
@@ -33,8 +33,10 @@ void pds_vfio_state_mutex_unlock(struct pds_vfio_pci_device *pds_vfio)
if (pds_vfio->deferred_reset) {
pds_vfio->deferred_reset = false;
if (pds_vfio->state == VFIO_DEVICE_STATE_ERROR) {
+ spin_unlock(&pds_vfio->reset_lock);
pds_vfio_put_restore_file(pds_vfio);
pds_vfio_put_save_file(pds_vfio);
+ spin_lock(&pds_vfio->reset_lock);
pds_vfio_dirty_disable(pds_vfio, false);
}
pds_vfio->state = pds_vfio->deferred_reset_state;
--
2.17.1