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Message-Id: <20230615044451.5580-6-decui@microsoft.com>
Date: Wed, 14 Jun 2023 21:44:51 -0700
From: Dexuan Cui <decui@...rosoft.com>
To: bhelgaas@...gle.com, davem@...emloft.net, decui@...rosoft.com,
edumazet@...gle.com, haiyangz@...rosoft.com, jakeo@...rosoft.com,
kuba@...nel.org, kw@...ux.com, kys@...rosoft.com, leon@...nel.org,
linux-pci@...r.kernel.org, lpieralisi@...nel.org,
mikelley@...rosoft.com, pabeni@...hat.com, robh@...nel.org,
saeedm@...dia.com, wei.liu@...nel.org, longli@...rosoft.com,
boqun.feng@...il.com, ssengar@...rosoft.com, helgaas@...nel.org
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
josete@...rosoft.com, simon.horman@...igine.com,
stable@...r.kernel.org
Subject: [PATCH v4 5/5] PCI: hv: Add a per-bus mutex state_lock
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@...rosoft.com>
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Acked-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: stable@...r.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(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 1a5296fad1c48..2d93d0c4f10db 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -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;
--
2.25.1
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