Kdump could fail sometime on Hyper-V guest over Accelerated Network
interface. This is because the retry in hv_pci_enter_d0() releases
child device strurctures in hv_pci_bus_exit(). Although there is
a second asynchronous device relations message sending from the host,
if this message arrives guest after hv_send_resource_allocated() is
called, the retry would fail.
Fix the problem by moving retry to hv_pci_probe() and starting retry
from hv_pci_query_relations() call. This will cause a device relations
message to arrive guest synchronously. The guest would be able to
rebuild the child device structures before calling
hv_send_resource_allocated().
This problem only happens on Accelerated Network or SRIOV devices as
only such devices currently are attached under vmbus PCI bridge.
Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
Signed-off-by: Wei Hu <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
---
v2: Adding Fixes tag according to Michael Kelley's review comment.
v3: Fix couple typos and reword commit message to make it clearer.
Thanks the comments from Bjorn Helgaas.
v4: Adding more problem descritpions in the commit message
and code upon request from Lorenze Pieralisi.
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 bf40ff09c99d..d1758986fbc9 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;
--
2.20.1
On Mon, Jul 27, 2020 at 03:17:31PM +0800, Wei Hu wrote:
> Kdump could fail sometime on Hyper-V guest over Accelerated Network
> interface. This is because the retry in hv_pci_enter_d0() releases
> child device strurctures in hv_pci_bus_exit(). Although there is
> a second asynchronous device relations message sending from the host,
> if this message arrives guest after hv_send_resource_allocated() is
> called, the retry would fail.
>
> Fix the problem by moving retry to hv_pci_probe() and starting retry
> from hv_pci_query_relations() call. This will cause a device relations
> message to arrive guest synchronously. The guest would be able to
> rebuild the child device structures before calling
> hv_send_resource_allocated().
>
> This problem only happens on Accelerated Network or SRIOV devices as
> only such devices currently are attached under vmbus PCI bridge.
>
> Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
> Signed-off-by: Wei Hu <[email protected]>
> Reviewed-by: Michael Kelley <[email protected]>
> ---
> v2: Adding Fixes tag according to Michael Kelley's review comment.
> v3: Fix couple typos and reword commit message to make it clearer.
> Thanks the comments from Bjorn Helgaas.
> v4: Adding more problem descritpions in the commit message
> and code upon request from Lorenze Pieralisi.
>
> 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
I edited commit log and a comment in the code to fix a typo and pushed
out to pci/hv.
Thanks,
Lorenzo
> index bf40ff09c99d..d1758986fbc9 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;
>
> --
> 2.20.1
>
> -----Original Message-----
> From: Lorenzo Pieralisi <[email protected]>
> Sent: Monday, July 27, 2020 7:19 PM
> To: Wei Hu <[email protected]>
> Cc: KY Srinivasan <[email protected]>; Haiyang Zhang
> <[email protected]>; Stephen Hemminger <[email protected]>;
> [email protected]; [email protected]; [email protected]; linux-
> [email protected]; [email protected]; linux-
> [email protected]; Dexuan Cui <[email protected]>; Michael Kelley
> <[email protected]>
> Subject: Re: [PATCH v4] PCI: hv: Fix a timing issue which causes kdump to fail
> occasionally
>
> On Mon, Jul 27, 2020 at 03:17:31PM +0800, Wei Hu wrote:
> > Kdump could fail sometime on Hyper-V guest over Accelerated Network
> > interface. This is because the retry in hv_pci_enter_d0() releases
> > child device strurctures in hv_pci_bus_exit(). Although there is a
> > second asynchronous device relations message sending from the host, if
> > this message arrives guest after hv_send_resource_allocated() is
> > called, the retry would fail.
> >
> > Fix the problem by moving retry to hv_pci_probe() and starting retry
> > from hv_pci_query_relations() call. This will cause a device
> > relations message to arrive guest synchronously. The guest would be
> > able to rebuild the child device structures before calling
> > hv_send_resource_allocated().
> >
> > This problem only happens on Accelerated Network or SRIOV devices as
> > only such devices currently are attached under vmbus PCI bridge.
> >
> > Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid
> > device state")
> > Signed-off-by: Wei Hu <[email protected]>
> > Reviewed-by: Michael Kelley <[email protected]>
> > ---
> > v2: Adding Fixes tag according to Michael Kelley's review comment.
> > v3: Fix couple typos and reword commit message to make it clearer.
> > Thanks the comments from Bjorn Helgaas.
> > v4: Adding more problem descritpions in the commit message
> > and code upon request from Lorenze Pieralisi.
> >
> > 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
>
> I edited commit log and a comment in the code to fix a typo and pushed out to
> pci/hv.
>
> Thanks,
> Lorenzo
>
Thanks Lorenzo. Appreciate your helps!
Wei