diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/pci/pci.c | 155 | ||||
| -rw-r--r-- | drivers/vfio/pci/vfio_pci.c | 29 |
2 files changed, 164 insertions, 20 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 95c97bec8018..b6d4afa8ba40 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3250,6 +3250,18 @@ static void pci_dev_lock(struct pci_dev *dev) device_lock(&dev->dev); } +/* Return 1 on successful lock, 0 on contention */ +static int pci_dev_trylock(struct pci_dev *dev) +{ + if (pci_cfg_access_trylock(dev)) { + if (device_trylock(&dev->dev)) + return 1; + pci_cfg_access_unlock(dev); + } + + return 0; +} + static void pci_dev_unlock(struct pci_dev *dev) { device_unlock(&dev->dev); @@ -3393,6 +3405,34 @@ int pci_reset_function(struct pci_dev *dev) } EXPORT_SYMBOL_GPL(pci_reset_function); +/** + * pci_try_reset_function - quiesce and reset a PCI device function + * @dev: PCI device to reset + * + * Same as above, except return -EAGAIN if unable to lock device. + */ +int pci_try_reset_function(struct pci_dev *dev) +{ + int rc; + + rc = pci_dev_reset(dev, 1); + if (rc) + return rc; + + pci_dev_save_and_disable(dev); + + if (pci_dev_trylock(dev)) { + rc = __pci_dev_reset(dev, 0); + pci_dev_unlock(dev); + } else + rc = -EAGAIN; + + pci_dev_restore(dev); + + return rc; +} +EXPORT_SYMBOL_GPL(pci_try_reset_function); + /* Lock devices from the top of the tree down */ static void pci_bus_lock(struct pci_bus *bus) { @@ -3417,6 +3457,32 @@ static void pci_bus_unlock(struct pci_bus *bus) } } +/* Return 1 on successful lock, 0 on contention */ +static int pci_bus_trylock(struct pci_bus *bus) +{ + struct pci_dev *dev; + + list_for_each_entry(dev, &bus->devices, bus_list) { + if (!pci_dev_trylock(dev)) + goto unlock; + if (dev->subordinate) { + if (!pci_bus_trylock(dev->subordinate)) { + pci_dev_unlock(dev); + goto unlock; + } + } + } + return 1; + +unlock: + list_for_each_entry_continue_reverse(dev, &bus->devices, bus_list) { + if (dev->subordinate) + pci_bus_unlock(dev->subordinate); + pci_dev_unlock(dev); + } + return 0; +} + /* Lock devices from the top of the tree down */ static void pci_slot_lock(struct pci_slot *slot) { @@ -3445,6 +3511,37 @@ static void pci_slot_unlock(struct pci_slot *slot) } } +/* Return 1 on successful lock, 0 on contention */ +static int pci_slot_trylock(struct pci_slot *slot) +{ + struct pci_dev *dev; + + list_for_each_entry(dev, &slot->bus->devices, bus_list) { + if (!dev->slot || dev->slot != slot) + continue; + if (!pci_dev_trylock(dev)) + goto unlock; + if (dev->subordinate) { + if (!pci_bus_trylock(dev->subordinate)) { + pci_dev_unlock(dev); + goto unlock; + } + } + } + return 1; + +unlock: + list_for_each_entry_continue_reverse(dev, + &slot->bus->devices, bus_list) { + if (!dev->slot || dev->slot != slot) + continue; + if (dev->subordinate) + pci_bus_unlock(dev->subordinate); + pci_dev_unlock(dev); + } + return 0; +} + /* Save and disable devices from the top of the tree down */ static void pci_bus_save_and_disable(struct pci_bus *bus) { @@ -3568,6 +3665,35 @@ int pci_reset_slot(struct pci_slot *slot) } EXPORT_SYMBOL_GPL(pci_reset_slot); +/** + * pci_try_reset_slot - Try to reset a PCI slot + * @slot: PCI slot to reset + * + * Same as above except return -EAGAIN if the slot cannot be locked + */ +int pci_try_reset_slot(struct pci_slot *slot) +{ + int rc; + + rc = pci_slot_reset(slot, 1); + if (rc) + return rc; + + pci_slot_save_and_disable(slot); + + if (pci_slot_trylock(slot)) { + might_sleep(); + rc = pci_reset_hotplug_slot(slot->hotplug, 0); + pci_slot_unlock(slot); + } else + rc = -EAGAIN; + + pci_slot_restore(slot); + + return rc; +} +EXPORT_SYMBOL_GPL(pci_try_reset_slot); + static int pci_bus_reset(struct pci_bus *bus, int probe) { if (!bus->self) @@ -3627,6 +3753,35 @@ int pci_reset_bus(struct pci_bus *bus) EXPORT_SYMBOL_GPL(pci_reset_bus); /** + * pci_try_reset_bus - Try to reset a PCI bus + * @bus: top level PCI bus to reset + * + * Same as above except return -EAGAIN if the bus cannot be locked + */ +int pci_try_reset_bus(struct pci_bus *bus) +{ + int rc; + + rc = pci_bus_reset(bus, 1); + if (rc) + return rc; + + pci_bus_save_and_disable(bus); + + if (pci_bus_trylock(bus)) { + might_sleep(); + pci_reset_bridge_secondary_bus(bus->self); + pci_bus_unlock(bus); + } else + rc = -EAGAIN; + + pci_bus_restore(bus); + + return rc; +} +EXPORT_SYMBOL_GPL(pci_try_reset_bus); + +/** * pcix_get_max_mmrbc - get PCI-X maximum designed memory read byte count * @dev: PCI device to query * diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 6ab71b9fcf8d..2319d206f630 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -139,25 +139,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE); /* - * Careful, device_lock may already be held. This is the case if - * a driver unbind is blocked. Try to get the locks ourselves to - * prevent a deadlock. + * Try to reset the device. The success of this is dependent on + * being able to lock the device, which is not always possible. */ if (vdev->reset_works) { - bool reset_done = false; - - if (pci_cfg_access_trylock(pdev)) { - if (device_trylock(&pdev->dev)) { - __pci_reset_function_locked(pdev); - reset_done = true; - device_unlock(&pdev->dev); - } - pci_cfg_access_unlock(pdev); - } - - if (!reset_done) - pr_warn("%s: Unable to acquire locks for reset of %s\n", - __func__, dev_name(&pdev->dev)); + int ret = pci_try_reset_function(pdev); + if (ret) + pr_warn("%s: Failed to reset device %s (%d)\n", + __func__, dev_name(&pdev->dev), ret); } pci_restore_state(pdev); @@ -514,7 +503,7 @@ static long vfio_pci_ioctl(void *device_data, } else if (cmd == VFIO_DEVICE_RESET) { return vdev->reset_works ? - pci_reset_function(vdev->pdev) : -EINVAL; + pci_try_reset_function(vdev->pdev) : -EINVAL; } else if (cmd == VFIO_DEVICE_GET_PCI_HOT_RESET_INFO) { struct vfio_pci_hot_reset_info hdr; @@ -684,8 +673,8 @@ reset_info_exit: &info, slot); if (!ret) /* User has access, do the reset */ - ret = slot ? pci_reset_slot(vdev->pdev->slot) : - pci_reset_bus(vdev->pdev->bus); + ret = slot ? pci_try_reset_slot(vdev->pdev->slot) : + pci_try_reset_bus(vdev->pdev->bus); hot_reset_release: for (i--; i >= 0; i--) |