This is a note to let you know that I've just added the patch titled
Revert "PCI: hv: Fix a timing issue which causes kdump to fail occasionally"
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
revert-pci-hv-fix-a-timing-issue-which-causes-kdump-to-fail-occasionally.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a847234e24d03d01a9566d1d9dcce018cc018d67 Mon Sep 17 00:00:00 2001
From: Dexuan Cui <decui@xxxxxxxxxxxxx>
Date: Wed, 14 Jun 2023 21:44:50 -0700
Subject: Revert "PCI: hv: Fix a timing issue which causes kdump to fail occasionally"
From: Dexuan Cui <decui@xxxxxxxxxxxxx>
commit a847234e24d03d01a9566d1d9dcce018cc018d67 upstream.
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The commit d6af2ed29c7c was originally made in July 2020 for RHEL 7.7,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@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Acked-by: Wei Hu <weh@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20230615044451.5580-5-decui@xxxxxxxxxxxxx
Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/controller/pci-hyperv.c | 71 +++++++++++++++++-------------------
1 file changed, 34 insertions(+), 37 deletions(-)
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -2842,8 +2842,10 @@ static int hv_pci_enter_d0(struct hv_dev
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
@@ -2870,6 +2872,38 @@ static int hv_pci_enter_d0(struct hv_dev
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",
@@ -3125,7 +3159,6 @@ static int hv_pci_probe(struct hv_device
struct hv_pcibus_device *hbus;
u16 dom_req, dom;
char *name;
- bool enter_d0_retry = true;
int ret;
/*
@@ -3246,47 +3279,11 @@ static int hv_pci_probe(struct hv_device
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;
Patches currently in stable-queue which might be from decui@xxxxxxxxxxxxx are
queue-5.10/pci-hv-fix-a-race-condition-in-hv_irq_unmask-that-can-cause-panic.patch
queue-5.10/revert-pci-hv-fix-a-timing-issue-which-causes-kdump-to-fail-occasionally.patch
queue-5.10/pci-hv-remove-the-useless-hv_pcichild_state-from-struct-hv_pci_dev.patch
queue-5.10/pci-hv-fix-a-race-condition-bug-in-hv_pci_query_relations.patch
