@@ -489,7 +489,10 @@ struct hv_pcibus_device {
struct fwnode_handle *fwnode;
/* Protocol version negotiated with the host */
enum pci_protocol_version_t protocol_version;
+
+ struct mutex state_lock;
enum hv_pcibus_state state;
+
struct hv_device *hdev;
resource_size_t low_mmio_space;
resource_size_t high_mmio_space;
@@ -2605,6 +2608,8 @@ static void pci_devices_present_work(struct work_struct *work)
if (!dr)
return;
+ mutex_lock(&hbus->state_lock);
+
/* First, mark all existing children as reported missing. */
spin_lock_irqsave(&hbus->device_list_lock, flags);
list_for_each_entry(hpdev, &hbus->children, list_entry) {
@@ -2686,6 +2691,8 @@ static void pci_devices_present_work(struct work_struct *work)
break;
}
+ mutex_unlock(&hbus->state_lock);
+
kfree(dr);
}
@@ -2834,6 +2841,8 @@ static void hv_eject_device_work(struct work_struct *work)
hpdev = container_of(work, struct hv_pci_dev, wrk);
hbus = hpdev->hbus;
+ mutex_lock(&hbus->state_lock);
+
/*
* Ejection can come before or after the PCI bus has been set up, so
* attempt to find it and tear down the bus state, if it exists. This
@@ -2870,6 +2879,8 @@ static void hv_eject_device_work(struct work_struct *work)
put_pcichild(hpdev);
put_pcichild(hpdev);
/* hpdev has been freed. Do not use it any more. */
+
+ mutex_unlock(&hbus->state_lock);
}
/**
@@ -3636,6 +3647,7 @@ static int hv_pci_probe(struct hv_device *hdev,
return -ENOMEM;
hbus->bridge = bridge;
+ mutex_init(&hbus->state_lock);
hbus->state = hv_pcibus_init;
hbus->wslot_res_allocated = -1;
@@ -3745,9 +3757,11 @@ static int hv_pci_probe(struct hv_device *hdev,
if (ret)
goto free_irq_domain;
+ mutex_lock(&hbus->state_lock);
+
ret = hv_pci_enter_d0(hdev);
if (ret)
- goto free_irq_domain;
+ goto release_state_lock;
ret = hv_pci_allocate_bridge_windows(hbus);
if (ret)
@@ -3765,12 +3779,15 @@ static int hv_pci_probe(struct hv_device *hdev,
if (ret)
goto free_windows;
+ mutex_unlock(&hbus->state_lock);
return 0;
free_windows:
hv_pci_free_bridge_windows(hbus);
exit_d0:
(void) hv_pci_bus_exit(hdev, true);
+release_state_lock:
+ mutex_unlock(&hbus->state_lock);
free_irq_domain:
irq_domain_remove(hbus->irq_domain);
free_fwnode:
@@ -4020,20 +4037,26 @@ static int hv_pci_resume(struct hv_device *hdev)
if (ret)
goto out;
+ mutex_lock(&hbus->state_lock);
+
ret = hv_pci_enter_d0(hdev);
if (ret)
- goto out;
+ goto release_state_lock;
ret = hv_send_resources_allocated(hdev);
if (ret)
- goto out;
+ goto release_state_lock;
prepopulate_bars(hbus);
hv_pci_restore_msi_state(hbus);
hbus->state = hv_pcibus_installed;
+ mutex_unlock(&hbus->state_lock);
return 0;
+
+release_state_lock:
+ mutex_unlock(&hbus->state_lock);
out:
vmbus_close(hdev->channel);
return ret;
In the case of fast device addition/removal, it's possible that hv_eject_device_work() can start to run before create_root_hv_pci_bus() starts to run; as a result, the pci_get_domain_bus_and_slot() in hv_eject_device_work() can return a 'pdev' of NULL, and hv_eject_device_work() can remove the 'hpdev', and immediately send a message PCI_EJECTION_COMPLETE to the host, and the host immediately unassigns the PCI device from the guest; meanwhile, create_root_hv_pci_bus() and the PCI device driver can be probing the dead PCI device and reporting timeout errors. Fix the issue by adding a per-bus mutex 'state_lock' and grabbing the mutex before powering on the PCI bus in hv_pci_enter_d0(): when hv_eject_device_work() starts to run, it's able to find the 'pdev' and call pci_stop_and_remove_bus_device(pdev): if the PCI device driver has loaded, the PCI device driver's probe() function is already called in create_root_hv_pci_bus() -> pci_bus_add_devices(), and now hv_eject_device_work() -> pci_stop_and_remove_bus_device() is able to call the PCI device driver's remove() function and remove the device reliably; if the PCI device driver hasn't loaded yet, the function call hv_eject_device_work() -> pci_stop_and_remove_bus_device() is able to remove the PCI device reliably and the PCI device driver's probe() function won't be called; if the PCI device driver's probe() is already running (e.g., systemd-udev is loading the PCI device driver), it must be holding the per-device lock, and after the probe() finishes and releases the lock, hv_eject_device_work() -> pci_stop_and_remove_bus_device() is able to proceed to remove the device reliably. Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs") Signed-off-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Lorenzo Pieralisi <lpieralisi@kernel.org> Cc: stable@vger.kernel.org --- v2: Removed the "debug code". Fixed the "goto out" in hv_pci_resume() [Michael Kelley] Added Cc:stable v3: Added Michael's Reviewed-by. v4: Added Lorenzo's Acked-by. drivers/pci/controller/pci-hyperv.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-)