Commit bc4fba77 authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio-pci: Attempt bus/slot reset on release



Each time a device is released, mark whether a local reset was
successful or whether a bus/slot reset is needed.  If a reset is
needed and all of the affected devices are bound to vfio-pci and
unused, allow the reset.  This is most useful when the userspace
driver is killed and releases all the devices in an unclean state,
such as when a QEMU VM quits.
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 61d79256
......@@ -39,6 +39,8 @@ MODULE_PARM_DESC(nointxmask,
static DEFINE_MUTEX(driver_lock);
static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
static int vfio_pci_enable(struct vfio_pci_device *vdev)
{
struct pci_dev *pdev = vdev->pdev;
......@@ -123,6 +125,8 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
vdev->barmap[bar] = NULL;
}
vdev->needs_reset = true;
/*
* If we have saved state, restore it. If we can reset the device,
* even better. Resetting with current state seems better than
......@@ -154,11 +158,15 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
if (ret)
pr_warn("%s: Failed to reset device %s (%d)\n",
__func__, dev_name(&pdev->dev), ret);
else
vdev->needs_reset = false;
}
pci_restore_state(pdev);
out:
pci_disable_device(pdev);
vfio_pci_try_bus_reset(vdev);
}
static void vfio_pci_release(void *device_data)
......@@ -923,6 +931,110 @@ static struct pci_driver vfio_pci_driver = {
.err_handler = &vfio_err_handlers,
};
/*
* Test whether a reset is necessary and possible. We mark devices as
* needs_reset when they are released, but don't have a function-local reset
* available. If any of these exist in the affected devices, we want to do
* a bus/slot reset. We also need all of the affected devices to be unused,
* so we abort if any device has a non-zero refcnt. driver_lock prevents a
* device from being opened during the scan or unbound from vfio-pci.
*/
static int vfio_pci_test_bus_reset(struct pci_dev *pdev, void *data)
{
bool *needs_reset = data;
struct pci_driver *pci_drv = ACCESS_ONCE(pdev->driver);
int ret = -EBUSY;
if (pci_drv == &vfio_pci_driver) {
struct vfio_device *device;
struct vfio_pci_device *vdev;
device = vfio_device_get_from_dev(&pdev->dev);
if (!device)
return ret;
vdev = vfio_device_data(device);
if (vdev) {
if (vdev->needs_reset)
*needs_reset = true;
if (!vdev->refcnt)
ret = 0;
}
vfio_device_put(device);
}
/*
* TODO: vfio-core considers groups to be viable even if some devices
* are attached to known drivers, like pci-stub or pcieport. We can't
* freeze devices from being unbound to those drivers like we can
* here though, so it would be racy to test for them. We also can't
* use device_lock() to prevent changes as that would interfere with
* PCI-core taking device_lock during bus reset. For now, we require
* devices to be bound to vfio-pci to get a bus/slot reset on release.
*/
return ret;
}
/* Clear needs_reset on all affected devices after successful bus/slot reset */
static int vfio_pci_clear_needs_reset(struct pci_dev *pdev, void *data)
{
struct pci_driver *pci_drv = ACCESS_ONCE(pdev->driver);
if (pci_drv == &vfio_pci_driver) {
struct vfio_device *device;
struct vfio_pci_device *vdev;
device = vfio_device_get_from_dev(&pdev->dev);
if (!device)
return 0;
vdev = vfio_device_data(device);
if (vdev)
vdev->needs_reset = false;
vfio_device_put(device);
}
return 0;
}
/*
* Attempt to do a bus/slot reset if there are devices affected by a reset for
* this device that are needs_reset and all of the affected devices are unused
* (!refcnt). Callers of this function are required to hold driver_lock such
* that devices can not be unbound from vfio-pci or opened by a user while we
* test for and perform a bus/slot reset.
*/
static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev)
{
bool needs_reset = false, slot = false;
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_for_each_slot_or_bus(vdev->pdev,
vfio_pci_test_bus_reset,
&needs_reset, slot) || !needs_reset)
return;
if (slot)
ret = pci_try_reset_slot(vdev->pdev->slot);
else
ret = pci_try_reset_bus(vdev->pdev->bus);
if (ret)
return;
vfio_pci_for_each_slot_or_bus(vdev->pdev,
vfio_pci_clear_needs_reset, NULL, slot);
}
static void __exit vfio_pci_cleanup(void)
{
pci_unregister_driver(&vfio_pci_driver);
......
......@@ -54,6 +54,7 @@ struct vfio_pci_device {
bool extended_caps;
bool bardirty;
bool has_vga;
bool needs_reset;
struct pci_saved_state *pci_saved_state;
int refcnt;
struct eventfd_ctx *err_trigger;
......
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