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Revert "PCI: hv: Fix a timing issue which causes kdump to fail occasionally"

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commit a847234e24d03d01a9566d1d9dcce018cc018d67 upstream.

This reverts commit d6af2ed29c.

The statement "the hv_pci_bus_exit() call releases structures of all its
child devices" in commit d6af2ed29c 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The commit d6af2ed29c was originally made in July 2020 for RHEL 7.7,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@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Wei Hu <weh@microsoft.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230615044451.5580-5-decui@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dexuan Cui 2023-06-14 21:44:50 -07:00 committed by Greg Kroah-Hartman
parent 79ceb758e3
commit 8b74846769
1 changed files with 34 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
drivers/pci/controller/pci-hyperv.c
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@ -2842,8 +2842,10 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
struct pci_bus_d0_entry *d0_entry; struct pci_bus_d0_entry *d0_entry;
struct hv_pci_compl comp_pkt; struct hv_pci_compl comp_pkt;
struct pci_packet *pkt; struct pci_packet *pkt;
bool retry = true;
int ret; int ret;
enter_d0_retry:
/* /*
* Tell the host that the bus is ready to use, and moved into the * Tell the host that the bus is ready to use, and moved into the
* powered-on state. This includes telling the host which region * powered-on state. This includes telling the host which region
@ -2870,6 +2872,38 @@ static int hv_pci_enter_d0(struct hv_device *hdev)
if (ret) if (ret)
goto exit; 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) { if (comp_pkt.completion_status < 0) {
dev_err(&hdev->device, dev_err(&hdev->device,
"PCI Pass-through VSP failed D0 Entry with status %x\n", "PCI Pass-through VSP failed D0 Entry with status %x\n",
@ -3125,7 +3159,6 @@ static int hv_pci_probe(struct hv_device *hdev,
struct hv_pcibus_device *hbus; struct hv_pcibus_device *hbus;
u16 dom_req, dom; u16 dom_req, dom;
char *name; char *name;
bool enter_d0_retry = true;
int ret; int ret;
/* /*
@ -3246,47 +3279,11 @@ static int hv_pci_probe(struct hv_device *hdev,
if (ret) if (ret)
goto free_fwnode; goto free_fwnode;
retry:
ret = hv_pci_query_relations(hdev); ret = hv_pci_query_relations(hdev);
if (ret) if (ret)
goto free_irq_domain; goto free_irq_domain;
ret = hv_pci_enter_d0(hdev); 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) if (ret)
goto free_irq_domain; goto free_irq_domain;