vfio_pci_try_bus_reset() is triggering a reset of the entire_dev set if any device within it has accumulated a needs_reset. This reset can only be done once all of the drivers operating the PCI devices to be reset are in a known safe state.
Make this clearer by directly operating on the dev_set instead of the vfio_pci_device. Rename the function to vfio_pci_dev_set_try_reset().
Use the device list inside the dev_set to check that all drivers are in a safe state instead of working backwards from the pci_device.
The dev_set->lock directly prevents devices from joining/leaving the set, or changing their state, which further implies the pci_device cannot change drivers or that the vfio_device be freed, eliminating the need for get/put's.
If a pci_device to be reset is not in the dev_set then the reset cannot be used as we can't know what the state of that driver is. Directly measure this by checking that every pci_device is in the dev_set - which effectively proves that VFIO drivers are attached to everything.
Remove the odd interaction around vfio_pci_set_power_state() - have the only caller avoid its redundant vfio_pci_set_power_state() instead of avoiding it inside vfio_pci_dev_set_try_reset().
This restructuring corrects a call to pci_dev_driver() without holding the device_lock() and removes a hard wiring to &vfio_pci_driver.
Signed-off-by: Jason Gunthorpe jgg@nvidia.com --- drivers/vfio/pci/vfio_pci.c | 182 +++++++++++++++++------------------- 1 file changed, 86 insertions(+), 96 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 5d6db93d6c680f..0147f04c91b2fb 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -223,7 +223,7 @@ static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev) } }
-static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev); +static bool vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set); static void vfio_pci_disable(struct vfio_pci_device *vdev); static int vfio_pci_try_zap_and_vma_lock_cb(struct pci_dev *pdev, void *data);
@@ -404,6 +404,9 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) struct vfio_pci_ioeventfd *ioeventfd, *ioeventfd_tmp; int i, bar;
+ /* For needs_reset */ + lockdep_assert_held(&vdev->vdev.dev_set->lock); + /* Stop the device from further DMA */ pci_clear_master(pdev);
@@ -487,9 +490,7 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) out: pci_disable_device(pdev);
- vfio_pci_try_bus_reset(vdev); - - if (!disable_idle_d3) + if (!vfio_pci_dev_set_try_reset(vdev->vdev.dev_set) && !disable_idle_d3) vfio_pci_set_power_state(vdev, PCI_D3hot); }
@@ -2145,36 +2146,6 @@ static struct pci_driver vfio_pci_driver = { .err_handler = &vfio_err_handlers, };
-static int vfio_pci_get_unused_devs(struct pci_dev *pdev, void *data) -{ - struct vfio_devices *devs = data; - struct vfio_device *device; - struct vfio_pci_device *vdev; - - if (devs->cur_index == devs->max_index) - return -ENOSPC; - - device = vfio_device_get_from_dev(&pdev->dev); - if (!device) - return -EINVAL; - - if (pci_dev_driver(pdev) != &vfio_pci_driver) { - vfio_device_put(device); - return -EBUSY; - } - - vdev = container_of(device, struct vfio_pci_device, vdev); - - /* Fault if the device is not unused */ - if (device->open_count) { - vfio_device_put(device); - return -EBUSY; - } - - devs->devices[devs->cur_index++] = vdev; - return 0; -} - static int vfio_pci_try_zap_and_vma_lock_cb(struct pci_dev *pdev, void *data) { struct vfio_devices *devs = data; @@ -2208,79 +2179,98 @@ static int vfio_pci_try_zap_and_vma_lock_cb(struct pci_dev *pdev, void *data) return 0; }
+static int vfio_pci_is_device_in_set(struct pci_dev *pdev, void *data) +{ + struct vfio_device_set *dev_set = data; + struct vfio_device *cur; + + list_for_each_entry(cur, &dev_set->device_list, dev_set_list) + if (cur->dev == &pdev->dev) + return 0; + return -EBUSY; +} + /* - * If a bus or slot reset is available for the provided device and: + * vfio-core considers a group to be viable and will create a vfio_device even + * if some devices are bound to drivers like pci-stub or pcieport. Here we + * require all PCI devices to be inside our dev_set since that ensures they stay + * put and that every driver controlling the device can co-ordinate with the + * device reset. + * + * Returns the pci_dev to pass to pci_reset_bus() if every PCI device to be + * reset is inside the dev_set, and pci_reset_bus() can succeed. NULL otherwise. + */ +static struct pci_dev * +vfio_pci_dev_set_resettable(struct vfio_device_set *dev_set) +{ + struct pci_dev *pdev; + + lockdep_assert_held(&dev_set->lock); + + /* + * By definition all PCI devices in the dev_set share the same PCI + * reset, so any pci_dev will have the same outcomes for + * pci_probe_reset_*() and pci_reset_bus(). + */ + pdev = list_first_entry(&dev_set->device_list, struct vfio_pci_device, + vdev.dev_set_list)->pdev; + + /* pci_reset_bus() is supported */ + if (pci_probe_reset_slot(pdev->slot) && pci_probe_reset_bus(pdev->bus)) + return NULL; + + if (vfio_pci_for_each_slot_or_bus(pdev, vfio_pci_is_device_in_set, + dev_set, + !pci_probe_reset_slot(pdev->slot))) + return NULL; + return pdev; +} + +static bool vfio_pci_dev_set_needs_reset(struct vfio_device_set *dev_set) +{ + struct vfio_pci_device *cur; + bool needs_reset = false; + + list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list) { + /* No VFIO device in the set can have an open device FD */ + if (cur->vdev.open_count) + return false; + needs_reset |= cur->needs_reset; + } + return needs_reset; +} + +/* + * If a bus or slot reset is available for the provided dev_set and: * - All of the devices affected by that bus or slot reset are unused - * (!refcnt) * - At least one of the affected devices is marked dirty via * needs_reset (such as by lack of FLR support) - * Then attempt to perform that bus or slot reset. Callers are required - * to hold vdev->dev_set->lock, protecting the bus/slot reset group from - * concurrent opens. A vfio_device reference is acquired for each device - * to prevent unbinds during the reset operation. - * - * NB: vfio-core considers a group to be viable even if some devices are - * bound to drivers like pci-stub or pcieport. Here we require all devices - * to be bound to vfio_pci since that's the only way we can be sure they - * stay put. + * Then attempt to perform that bus or slot reset. + * Returns true if the dev_set was reset. */ -static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev) +static bool vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set) { - struct vfio_devices devs = { .cur_index = 0 }; - int i = 0, ret = -EINVAL; - bool slot = false; - struct vfio_pci_device *tmp; + struct vfio_pci_device *cur; + struct pci_dev *pdev; + int ret;
- if (!pci_probe_reset_slot(vdev->pdev->slot)) - slot = true; - else if (pci_probe_reset_bus(vdev->pdev->bus)) - return; + if (!vfio_pci_dev_set_needs_reset(dev_set)) + return false;
- if (vfio_pci_for_each_slot_or_bus(vdev->pdev, vfio_pci_count_devs, - &i, slot) || !i) - return; + pdev = vfio_pci_dev_set_resettable(dev_set); + if (!pdev) + return false;
- devs.max_index = i; - devs.devices = kcalloc(i, sizeof(struct vfio_device *), GFP_KERNEL); - if (!devs.devices) - return; + ret = pci_reset_bus(pdev); + if (ret) + return false;
- if (vfio_pci_for_each_slot_or_bus(vdev->pdev, - vfio_pci_get_unused_devs, - &devs, slot)) - goto put_devs; - - /* Does at least one need a reset? */ - for (i = 0; i < devs.cur_index; i++) { - tmp = devs.devices[i]; - if (tmp->needs_reset) { - ret = pci_reset_bus(vdev->pdev); - break; - } + list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list) { + cur->needs_reset = false; + if (!disable_idle_d3) + vfio_pci_set_power_state(cur, PCI_D3hot); } - -put_devs: - for (i = 0; i < devs.cur_index; i++) { - tmp = devs.devices[i]; - - /* - * If reset was successful, affected devices no longer need - * a reset and we should return all the collateral devices - * to low power. If not successful, we either didn't reset - * the bus or timed out waiting for it, so let's not touch - * the power state. - */ - if (!ret) { - tmp->needs_reset = false; - - if (tmp != vdev && !disable_idle_d3) - vfio_pci_set_power_state(tmp, PCI_D3hot); - } - - vfio_device_put(&tmp->vdev); - } - - kfree(devs.devices); + return true; }
static void __exit vfio_pci_cleanup(void)