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Message-Id: <20230615044451.5580-5-decui@microsoft.com>
Date: Wed, 14 Jun 2023 21:44:50 -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 4/5] Revert "PCI: hv: Fix a timing issue which causes kdump to fail occasionally"
This reverts commit d6af2ed29c7c1c311b96dac989dcb991e90ee195.
The statement "the hv_pci_bus_exit() call releases structures of all its
child devices" in commit d6af2ed29c7c is not true: in the path
hv_pci_probe() -> hv_pci_enter_d0() -> hv_pci_bus_exit(hdev, true): the
parameter "keep_devs" is true, so hv_pci_bus_exit() does *not* release the
child "struct hv_pci_dev *hpdev" that is created earlier in
pci_devices_present_work() -> new_pcichild_device().
The commit d6af2ed29c7c was originally made in July 2020 for RHEL 7.7,
where the old version of hv_pci_bus_exit() was used; when the commit was
rebased and merged into the upstream, people didn't notice that it's
not really necessary. The commit itself doesn't cause any issue, but it
makes hv_pci_probe() more complicated. Revert it to facilitate some
upcoming changes to hv_pci_probe().
Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Acked-by: Wei Hu <weh@...rosoft.com>
Cc: stable@...r.kernel.org
---
v2:
No change to the patch body.
Added Wei Hu's Acked-by.
Added Cc:stable
v3:
Added Michael's Reviewed-by.
v4:
NO change since v3.
drivers/pci/controller/pci-hyperv.c | 71 ++++++++++++++---------------
1 file changed, 34 insertions(+), 37 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index a826b41c949a1..1a5296fad1c48 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3318,8 +3318,10 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
struct pci_bus_d0_entry *d0_entry;
struct hv_pci_compl comp_pkt;
struct pci_packet *pkt;
+ bool retry = true;
int ret;
+enter_d0_retry:
/*
* Tell the host that the bus is ready to use, and moved into the
* powered-on state. This includes telling the host which region
@@ -3346,6 +3348,38 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
if (ret)
goto exit;
+ /*
+ * In certain case (Kdump) the pci device of interest was
+ * not cleanly shut down and resource is still held on host
+ * side, the host could return invalid device status.
+ * We need to explicitly request host to release the resource
+ * and try to enter D0 again.
+ */
+ if (comp_pkt.completion_status < 0 && retry) {
+ retry = false;
+
+ dev_err(&hdev->device, "Retrying D0 Entry\n");
+
+ /*
+ * Hv_pci_bus_exit() calls hv_send_resource_released()
+ * to free up resources of its child devices.
+ * In the kdump kernel we need to set the
+ * wslot_res_allocated to 255 so it scans all child
+ * devices to release resources allocated in the
+ * normal kernel before panic happened.
+ */
+ hbus->wslot_res_allocated = 255;
+
+ ret = hv_pci_bus_exit(hdev, true);
+
+ if (ret == 0) {
+ kfree(pkt);
+ goto enter_d0_retry;
+ }
+ dev_err(&hdev->device,
+ "Retrying D0 failed with ret %d\n", ret);
+ }
+
if (comp_pkt.completion_status < 0) {
dev_err(&hdev->device,
"PCI Pass-through VSP failed D0 Entry with status %x\n",
@@ -3591,7 +3625,6 @@ static int hv_pci_probe(struct hv_device *hdev,
struct hv_pcibus_device *hbus;
u16 dom_req, dom;
char *name;
- bool enter_d0_retry = true;
int ret;
bridge = devm_pci_alloc_host_bridge(&hdev->device, 0);
@@ -3708,47 +3741,11 @@ static int hv_pci_probe(struct hv_device *hdev,
if (ret)
goto free_fwnode;
-retry:
ret = hv_pci_query_relations(hdev);
if (ret)
goto free_irq_domain;
ret = hv_pci_enter_d0(hdev);
- /*
- * In certain case (Kdump) the pci device of interest was
- * not cleanly shut down and resource is still held on host
- * side, the host could return invalid device status.
- * We need to explicitly request host to release the resource
- * and try to enter D0 again.
- * Since the hv_pci_bus_exit() call releases structures
- * of all its child devices, we need to start the retry from
- * hv_pci_query_relations() call, requesting host to send
- * the synchronous child device relations message before this
- * information is needed in hv_send_resources_allocated()
- * call later.
- */
- if (ret == -EPROTO && enter_d0_retry) {
- enter_d0_retry = false;
-
- dev_err(&hdev->device, "Retrying D0 Entry\n");
-
- /*
- * Hv_pci_bus_exit() calls hv_send_resources_released()
- * to free up resources of its child devices.
- * In the kdump kernel we need to set the
- * wslot_res_allocated to 255 so it scans all child
- * devices to release resources allocated in the
- * normal kernel before panic happened.
- */
- hbus->wslot_res_allocated = 255;
- ret = hv_pci_bus_exit(hdev, true);
-
- if (ret == 0)
- goto retry;
-
- dev_err(&hdev->device,
- "Retrying D0 failed with ret %d\n", ret);
- }
if (ret)
goto free_irq_domain;
--
2.25.1
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