+++ /dev/null
-From 85f69a1777ddc1b0f49608a99e61a6c57a5fa42f Mon Sep 17 00:00:00 2001
-From: Sasha Levin <sashal@kernel.org>
-Date: Mon, 27 Jul 2020 15:17:31 +0800
-Subject: PCI: hv: Fix a timing issue which causes kdump to fail occasionally
-
-From: Wei Hu <weh@microsoft.com>
-
-[ Upstream commit d6af2ed29c7c1c311b96dac989dcb991e90ee195 ]
-
-Kdump could fail sometime on Hyper-V guest because the retry in
-hv_pci_enter_d0() releases child device structures in hv_pci_bus_exit().
-
-Although there is a second asynchronous device relations message sending
-from the host, if this message arrives to the guest after
-hv_send_resource_allocated() is called, the retry would fail.
-
-Fix the problem by moving retry to hv_pci_probe() and start the retry
-from hv_pci_query_relations() call. This will cause a device relations
-message to arrive to the guest synchronously; the guest would then be
-able to rebuild the child device structures before calling
-hv_send_resource_allocated().
-
-Link: https://lore.kernel.org/r/20200727071731.18516-1-weh@microsoft.com
-Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
-Signed-off-by: Wei Hu <weh@microsoft.com>
-[lorenzo.pieralisi@arm.com: fixed a comment and commit log]
-Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
-Reviewed-by: Michael Kelley <mikelley@microsoft.com>
-Signed-off-by: Sasha Levin <sashal@kernel.org>
----
- drivers/pci/controller/pci-hyperv.c | 71 +++++++++++++++--------------
- 1 file changed, 37 insertions(+), 34 deletions(-)
-
-diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
-index bf40ff09c99d6..d0033ff6c1437 100644
---- a/drivers/pci/controller/pci-hyperv.c
-+++ b/drivers/pci/controller/pci-hyperv.c
-@@ -2759,10 +2759,8 @@ 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
-@@ -2789,38 +2787,6 @@ 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",
-@@ -3058,6 +3024,7 @@ 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;
-
- /*
-@@ -3178,11 +3145,47 @@ 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
-
projects / thirdparty / kernel / stable-queue.git / commitdiff
