Fix a long standing locking gap for missing pci_cfg_access_lock() while
manipulating bridge reset registers and configuration during
pci_reset_bus_function(). Add calling of pci_dev_lock() against the
bridge device before locking the device. The locking is conditional
depending on whether the trigger device has an upstream bridge. If
the device is a root port then there would be no upstream bridge and
thus the locking of the bridge is unnecessary. As part of calling
pci_dev_lock(), pci_cfg_access_lock() happens and blocks the writing
of PCI config space by user space.
Add lockdep assertion via pci_dev->cfg_access_lock in order to verify
pci_dev->block_cfg_access is set.
Co-developed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
drivers/pci/access.c | 4 ++++
drivers/pci/pci.c | 13 +++++++++++++
drivers/pci/probe.c | 3 +++
include/linux/lockdep.h | 5 +++++
include/linux/pci.h | 2 ++
5 files changed, 27 insertions(+)
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 6449056b57dd..36f10c7f9ef5 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -275,6 +275,8 @@ void pci_cfg_access_lock(struct pci_dev *dev)
{
might_sleep();
+ lock_map_acquire(&dev->cfg_access_lock);
+
raw_spin_lock_irq(&pci_lock);
if (dev->block_cfg_access)
pci_wait_cfg(dev);
@@ -329,6 +331,8 @@ void pci_cfg_access_unlock(struct pci_dev *dev)
raw_spin_unlock_irqrestore(&pci_lock, flags);
wake_up_all(&pci_cfg_wait);
+
+ lock_map_release(&dev->cfg_access_lock);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e5f243dd4288..482372f5d268 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4879,6 +4879,7 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
*/
int pci_bridge_secondary_bus_reset(struct pci_dev *dev)
{
+ lock_map_assert_held(&dev->cfg_access_lock);
pcibios_reset_secondary_bus(dev);
return pci_bridge_wait_for_secondary_bus(dev, "bus reset");
@@ -5245,11 +5246,20 @@ void pci_init_reset_methods(struct pci_dev *dev)
*/
int pci_reset_function(struct pci_dev *dev)
{
+ struct pci_dev *bridge;
int rc;
if (!pci_reset_supported(dev))
return -ENOTTY;
+ bridge = pci_upstream_bridge(dev);
+ /*
+ * If there's no upstream bridge, then no locking is needed since there is no
+ * upstream bridge configuration to hold consistent.
+ */
+ if (bridge)
+ pci_dev_lock(bridge);
+
pci_dev_lock(dev);
pci_dev_save_and_disable(dev);
@@ -5258,6 +5268,9 @@ int pci_reset_function(struct pci_dev *dev)
pci_dev_restore(dev);
pci_dev_unlock(dev);
+ if (bridge)
+ pci_dev_unlock(bridge);
+
return rc;
}
EXPORT_SYMBOL_GPL(pci_reset_function);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1325fbae2f28..a3da776bf986 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2543,6 +2543,9 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
dev->dev.dma_mask = &dev->dma_mask;
dev->dev.dma_parms = &dev->dma_parms;
dev->dev.coherent_dma_mask = 0xffffffffull;
+ lockdep_register_key(&dev->cfg_access_key);
+ lockdep_init_map(&dev->cfg_access_lock, dev_name(&dev->dev),
+ &dev->cfg_access_key, 0);
dma_set_max_seg_size(&dev->dev, 65536);
dma_set_seg_boundary(&dev->dev, 0xffffffff);
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 08b0d1d9d78b..5e51b0de4c4b 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -297,6 +297,9 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
.wait_type_inner = _wait_type, \
.lock_type = LD_LOCK_WAIT_OVERRIDE, }
+#define lock_map_assert_held(l) \
+ lockdep_assert(lock_is_held(l) != LOCK_STATE_NOT_HELD)
+
#else /* !CONFIG_LOCKDEP */
static inline void lockdep_init_task(struct task_struct *task)
@@ -388,6 +391,8 @@ extern int lockdep_is_held(const void *);
#define DEFINE_WAIT_OVERRIDE_MAP(_name, _wait_type) \
struct lockdep_map __maybe_unused _name = {}
+#define lock_map_assert_held(l) do { (void)(l); } while (0)
+
#endif /* !LOCKDEP */
#ifdef CONFIG_PROVE_LOCKING
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 16493426a04f..e4e7b175af54 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -413,6 +413,8 @@ struct pci_dev {
struct resource driver_exclusive_resource; /* driver exclusive resource ranges */
bool match_driver; /* Skip attaching driver */
+ struct lock_class_key cfg_access_key;
+ struct lockdep_map cfg_access_lock;
unsigned int transparent:1; /* Subtractive decode bridge */
unsigned int io_window:1; /* Bridge has I/O window */
--
2.44.0
