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PCI: Lock upstream bridge for pci_reset_function()

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Fix a long-standing locking gap for missing pci_cfg_access_lock() while
manipulating bridge reset registers and configuration during
pci_reset_bus_function().

If there is an upstream bridge, lock it before locking the device itself.
pci_dev_lock() calls pci_cfg_access_lock(), which blocks the writing of PCI
config space by user space.

Add lockdep assertion via pci_dev->cfg_access_lock to verify
pci_dev->block_cfg_access is set.

Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/20240502165851.1948523-3-dave.jiang@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Dave Jiang 2024-05-02 09:57:31 -07:00 committed by Bjorn Helgaas
parent 962f1e79e7
commit 7e89efc6e9
5 changed files with 27 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
drivers/pci/access.c
View file

@ -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);

13
drivers/pci/pci.c
View file

@ -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;
/*
* If there's no upstream bridge, no locking is needed since there is
* no upstream bridge configuration to hold consistent.
*/
bridge = pci_upstream_bridge(dev);
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);

3
drivers/pci/probe.c
View file

@ -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);

5
include/linux/lockdep.h
View file

@ -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

2
include/linux/pci.h
View file

@ -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 */