[PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Dexuan Cui]

I got the hypercall error code on Hyper-V 2008 R2 when keeping running
"rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe hv_utils"
in a Linux guest.

Without the patch, the driver can occasionally fail to load.

CC: "K. Y. Srinivasan" <kys@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 arch/x86/include/uapi/asm/hyperv.h | 1 +
 drivers/hv/connection.c            | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 90c458e..b9daffb 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -225,6 +225,7 @@
 #define HV_STATUS_INVALID_HYPERCALL_CODE	2
 #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
 #define HV_STATUS_INVALID_ALIGNMENT		4
+#define HV_STATUS_INVALID_CONNECTION_ID		18
 #define HV_STATUS_INSUFFICIENT_BUFFERS		19
 
 typedef struct _HV_REFERENCE_TSC_PAGE {
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index c4acd1c..8bd05f3 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
 		ret = hv_post_message(conn_id, 1, buffer, buflen);
 
 		switch (ret) {
+		case HV_STATUS_INVALID_CONNECTION_ID:
+			/*
+			 * We could get this if we send messages too
+			 * frequently or the host is under low resource
+			 * conditions: let's wait 1 more second before
+			 * retrying the hypercall.
+			 */
+			msleep(1000);
+			break;
 		case HV_STATUS_INSUFFICIENT_BUFFERS:
 			ret = -ENOMEM;
 		case -ENOMEM:
-- 
1.9.1

Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Vitaly Kuznetsov]

Dexuan Cui <decui@microsoft.com> writes:

> I got the hypercall error code on Hyper-V 2008 R2 when keeping running
> "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe hv_utils"
> in a Linux guest.
>
> Without the patch, the driver can occasionally fail to load.
>
> CC: "K. Y. Srinivasan" <kys@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>  arch/x86/include/uapi/asm/hyperv.h | 1 +
>  drivers/hv/connection.c            | 9 +++++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
> index 90c458e..b9daffb 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -225,6 +225,7 @@
>  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
>  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
>  #define HV_STATUS_INVALID_ALIGNMENT		4
> +#define HV_STATUS_INVALID_CONNECTION_ID		18
>  #define HV_STATUS_INSUFFICIENT_BUFFERS		19

The gap beween 4 and 18 tells me there are other codes here ;-) Are they
all 'permanent failures'?

>
>  typedef struct _HV_REFERENCE_TSC_PAGE {
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index c4acd1c..8bd05f3 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
>  		ret = hv_post_message(conn_id, 1, buffer, buflen);
>
>  		switch (ret) {
> +		case HV_STATUS_INVALID_CONNECTION_ID:
> +			/*
> +			 * We could get this if we send messages too
> +			 * frequently or the host is under low resource
> +			 * conditions: let's wait 1 more second before
> +			 * retrying the hypercall.
> +			 */
> +			msleep(1000);
> +			break;

In case it is our last try (No. 10) we will return '18' from the
function. I suggest we set ret = -ENOMEM here as well.

>  		case HV_STATUS_INSUFFICIENT_BUFFERS:
>  			ret = -ENOMEM;

Or should we treat these two equally? There is a smaller (100ms) sleep
between tries already, we can consider changing it instead.

>  		case -ENOMEM:

-- 
  Vitaly

RE: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Dexuan Cui]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Thursday, January 29, 2015 21:31 PM
> To: Dexuan Cui
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> HV_STATUS_INVALID_CONNECTION_ID
> 
> Dexuan Cui <decui@microsoft.com> writes:
> 
> > I got the hypercall error code on Hyper-V 2008 R2 when keeping running
> > "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe hv_utils"
> > in a Linux guest.
> >
> > Without the patch, the driver can occasionally fail to load.
> >
> > CC: "K. Y. Srinivasan" <kys@microsoft.com>
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > ---
> >  arch/x86/include/uapi/asm/hyperv.h | 1 +
> >  drivers/hv/connection.c            | 9 +++++++++
> >  2 files changed, 10 insertions(+)
> >
> > diff --git a/arch/x86/include/uapi/asm/hyperv.h
> b/arch/x86/include/uapi/asm/hyperv.h
> > index 90c458e..b9daffb 100644
> > --- a/arch/x86/include/uapi/asm/hyperv.h
> > +++ b/arch/x86/include/uapi/asm/hyperv.h
> > @@ -225,6 +225,7 @@
> >  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
> >  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
> >  #define HV_STATUS_INVALID_ALIGNMENT		4
> > +#define HV_STATUS_INVALID_CONNECTION_ID		18
> >  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> 
> The gap beween 4 and 18 tells me there are other codes here ;-) Are they
> all 'permanent failures'?
It looks we only need to care about these error codes here.

BTW, you can get all the hypercall error codes in the top level functional spec:
http://blogs.msdn.com/b/virtual_pc_guy/archive/2014/02/17/updated-hypervisor-top-level-functional-specification.aspx
For this hypercall (0x005c), see "14.9.7 HvPostMessage".

> >
> >  typedef struct _HV_REFERENCE_TSC_PAGE {
> > diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> > index c4acd1c..8bd05f3 100644
> > --- a/drivers/hv/connection.c
> > +++ b/drivers/hv/connection.c
> > @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
> >  		ret = hv_post_message(conn_id, 1, buffer, buflen);
> >
> >  		switch (ret) {
> > +		case HV_STATUS_INVALID_CONNECTION_ID:
> > +			/*
> > +			 * We could get this if we send messages too
> > +			 * frequently or the host is under low resource
> > +			 * conditions: let's wait 1 more second before
> > +			 * retrying the hypercall.
> > +			 */
> > +			msleep(1000);
> > +			break;
> 
> In case it is our last try (No. 10) we will return '18' from the
> function. I suggest we set ret = -ENOMEM here as well.
Thanks for the suggestion!

I think it would be better to add this to the case
HV_STATUS_INVALID_CONNECTION_ID:
 ret = -EAGAIN;
?

> >  		case HV_STATUS_INSUFFICIENT_BUFFERS:
> >  			ret = -ENOMEM;
> 
> Or should we treat these two equally? There is a smaller (100ms) sleep
> between tries already, we can consider changing it instead.
> 
> >  		case -ENOMEM:
> 
> --
>   Vitaly
In my experiments, in the HV_STATUS_INVALID_CONNECTION_ID case,
waiting 100ms is not enough sometimes, so I'd like to wait more time.
I agree with you both cases can wait 1000ms. I'll update my patch.

BTW, the " case -ENOMEM:" is not reachable(the hypervisor itself doesn't 
return -ENOMEM), I think. I can remove it.

Thanks,
-- Dexuan

Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Vitaly Kuznetsov]

Dexuan Cui <decui@microsoft.com> writes:

>> -----Original Message-----
>> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
>> Sent: Thursday, January 29, 2015 21:31 PM
>> To: Dexuan Cui
>> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
>> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
>> jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
>> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
>> HV_STATUS_INVALID_CONNECTION_ID
>> 
>> Dexuan Cui <decui@microsoft.com> writes:
>> 
>> > I got the hypercall error code on Hyper-V 2008 R2 when keeping running
>> > "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe hv_utils"
>> > in a Linux guest.
>> >
>> > Without the patch, the driver can occasionally fail to load.
>> >
>> > CC: "K. Y. Srinivasan" <kys@microsoft.com>
>> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
>> > ---
>> >  arch/x86/include/uapi/asm/hyperv.h | 1 +
>> >  drivers/hv/connection.c            | 9 +++++++++
>> >  2 files changed, 10 insertions(+)
>> >
>> > diff --git a/arch/x86/include/uapi/asm/hyperv.h
>> b/arch/x86/include/uapi/asm/hyperv.h
>> > index 90c458e..b9daffb 100644
>> > --- a/arch/x86/include/uapi/asm/hyperv.h
>> > +++ b/arch/x86/include/uapi/asm/hyperv.h
>> > @@ -225,6 +225,7 @@
>> >  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
>> >  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
>> >  #define HV_STATUS_INVALID_ALIGNMENT		4
>> > +#define HV_STATUS_INVALID_CONNECTION_ID		18
>> >  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
>> 
>> The gap beween 4 and 18 tells me there are other codes here ;-) Are they
>> all 'permanent failures'?
> It looks we only need to care about these error codes here.
>
> BTW, you can get all the hypercall error codes in the top level functional spec:
> http://blogs.msdn.com/b/virtual_pc_guy/archive/2014/02/17/updated-hypervisor-top-level-functional-specification.aspx
> For this hypercall (0x005c), see "14.9.7 HvPostMessage".

Thanks, interesting!

Btw, HV_STATUS_INSUFFICIENT_MEMORY looks suspicious, looks like we can
hit it as well...

I suggest we split all failures here in 2 classes:
1) permanent
2) worth retrying

and treat them accordingly (no big changes, just maybe group them within
hv_post_message() together as it is the only place where these codes are
being used).

>
>> >
>> >  typedef struct _HV_REFERENCE_TSC_PAGE {
>> > diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
>> > index c4acd1c..8bd05f3 100644
>> > --- a/drivers/hv/connection.c
>> > +++ b/drivers/hv/connection.c
>> > @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
>> >  		ret = hv_post_message(conn_id, 1, buffer, buflen);
>> >
>> >  		switch (ret) {
>> > +		case HV_STATUS_INVALID_CONNECTION_ID:
>> > +			/*
>> > +			 * We could get this if we send messages too
>> > +			 * frequently or the host is under low resource
>> > +			 * conditions: let's wait 1 more second before
>> > +			 * retrying the hypercall.
>> > +			 */
>> > +			msleep(1000);
>> > +			break;
>> 
>> In case it is our last try (No. 10) we will return '18' from the
>> function. I suggest we set ret = -ENOMEM here as well.
> Thanks for the suggestion!
>
> I think it would be better to add this to the case
> HV_STATUS_INVALID_CONNECTION_ID:
>  ret = -EAGAIN;
> ?

Yes, like fallthrough

>
>> >  		case HV_STATUS_INSUFFICIENT_BUFFERS:
>> >  			ret = -ENOMEM;
>> 
>> Or should we treat these two equally? There is a smaller (100ms) sleep
>> between tries already, we can consider changing it instead.
>> 
>> >  		case -ENOMEM:
>> 
>> --
>>   Vitaly
> In my experiments, in the HV_STATUS_INVALID_CONNECTION_ID case,
> waiting 100ms is not enough sometimes, so I'd like to wait more time.
> I agree with you both cases can wait 1000ms. I'll update my patch.
>
> BTW, the " case -ENOMEM:" is not reachable(the hypervisor itself doesn't 
> return -ENOMEM), I think. I can remove it.

hv_post_message() can return -EMSGSIZE or do_hypercall() return value
(which becomes u16 in hv_post_message()). So yes, I agree, -ENOMEM is
not possible.

>
> Thanks,
> -- Dexuan

-- 
  Vitaly

RE: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Dexuan Cui]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Saturday, January 31, 2015 1:29 AM
> To: Dexuan Cui
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> HV_STATUS_INVALID_CONNECTION_ID
> 
> Dexuan Cui <decui@microsoft.com> writes:
> 
> >> -----Original Message-----
> >> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> >> Sent: Thursday, January 29, 2015 21:31 PM
> >> To: Dexuan Cui
> >> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> >> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> >> jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
> >> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> >> HV_STATUS_INVALID_CONNECTION_ID
> >>
> >> Dexuan Cui <decui@microsoft.com> writes:
> >>
> >> > I got the hypercall error code on Hyper-V 2008 R2 when keeping running
> >> > "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe
> hv_utils"
> >> > in a Linux guest.
> >> >
> >> > Without the patch, the driver can occasionally fail to load.
> >> >
> >> > CC: "K. Y. Srinivasan" <kys@microsoft.com>
> >> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> >> > ---
> >> >  arch/x86/include/uapi/asm/hyperv.h | 1 +
> >> >  drivers/hv/connection.c            | 9 +++++++++
> >> >  2 files changed, 10 insertions(+)
> >> >
> >> > diff --git a/arch/x86/include/uapi/asm/hyperv.h
> >> b/arch/x86/include/uapi/asm/hyperv.h
> >> > index 90c458e..b9daffb 100644
> >> > --- a/arch/x86/include/uapi/asm/hyperv.h
> >> > +++ b/arch/x86/include/uapi/asm/hyperv.h
> >> > @@ -225,6 +225,7 @@
> >> >  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
> >> >  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
> >> >  #define HV_STATUS_INVALID_ALIGNMENT		4
> >> > +#define HV_STATUS_INVALID_CONNECTION_ID		18
> >> >  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> >>
> >> The gap beween 4 and 18 tells me there are other codes here ;-) Are they
> >> all 'permanent failures'?
> > It looks we only need to care about these error codes here.
> >
> > BTW, you can get all the hypercall error codes in the top level functional spec:
> > http://blogs.msdn.com/b/virtual_pc_guy/archive/2014/02/17/updated-
> hypervisor-top-level-functional-specification.aspx
> > For this hypercall (0x005c), see "14.9.7 HvPostMessage".
> 
> Thanks, interesting!
> 
> Btw, HV_STATUS_INSUFFICIENT_MEMORY looks suspicious, looks like we can
> hit it as well...
> 
> I suggest we split all failures here in 2 classes:
> 1) permanent
> 2) worth retrying
> 
> and treat them accordingly (no big changes, just maybe group them within
> hv_post_message() together as it is the only place where these codes are
> being used).
Thanks for the suggestion, Vitaly!
I'll send out  v2.

-- Dexuan

> >
> >> >
> >> >  typedef struct _HV_REFERENCE_TSC_PAGE {
> >> > diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> >> > index c4acd1c..8bd05f3 100644
> >> > --- a/drivers/hv/connection.c
> >> > +++ b/drivers/hv/connection.c
> >> > @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
> >> >  		ret = hv_post_message(conn_id, 1, buffer, buflen);
> >> >
> >> >  		switch (ret) {
> >> > +		case HV_STATUS_INVALID_CONNECTION_ID:
> >> > +			/*
> >> > +			 * We could get this if we send messages too
> >> > +			 * frequently or the host is under low resource
> >> > +			 * conditions: let's wait 1 more second before
> >> > +			 * retrying the hypercall.
> >> > +			 */
> >> > +			msleep(1000);
> >> > +			break;
> >>
> >> In case it is our last try (No. 10) we will return '18' from the
> >> function. I suggest we set ret = -ENOMEM here as well.
> > Thanks for the suggestion!
> >
> > I think it would be better to add this to the case
> > HV_STATUS_INVALID_CONNECTION_ID:
> >  ret = -EAGAIN;
> > ?
> 
> Yes, like fallthrough
> 
> >
> >> >  		case HV_STATUS_INSUFFICIENT_BUFFERS:
> >> >  			ret = -ENOMEM;
> >>
> >> Or should we treat these two equally? There is a smaller (100ms) sleep
> >> between tries already, we can consider changing it instead.
> >>
> >> >  		case -ENOMEM:
> >>
> >> --
> >>   Vitaly
> > In my experiments, in the HV_STATUS_INVALID_CONNECTION_ID case,
> > waiting 100ms is not enough sometimes, so I'd like to wait more time.
> > I agree with you both cases can wait 1000ms. I'll update my patch.
> >
> > BTW, the " case -ENOMEM:" is not reachable(the hypervisor itself doesn't
> > return -ENOMEM), I think. I can remove it.
> 
> hv_post_message() can return -EMSGSIZE or do_hypercall() return value
> (which becomes u16 in hv_post_message()). So yes, I agree, -ENOMEM is
> not possible.
> 
> >
> > Thanks,
> > -- Dexuan
> 
> --
>   Vitaly

RE: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[KY Srinivasan]

> -----Original Message-----
> From: Dexuan Cui
> Sent: Saturday, January 31, 2015 7:38 PM
> To: Vitaly Kuznetsov
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
> Subject: RE: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> HV_STATUS_INVALID_CONNECTION_ID
> 
> > -----Original Message-----
> > From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> > Sent: Saturday, January 31, 2015 1:29 AM
> > To: Dexuan Cui
> > Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> > driverdev- devel@linuxdriverproject.org; olaf@aepfle.de;
> > apw@canonical.com; jasowang@redhat.com; KY Srinivasan; Haiyang Zhang
> > Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> > HV_STATUS_INVALID_CONNECTION_ID
> >
> > Dexuan Cui <decui@microsoft.com> writes:
> >
> > >> -----Original Message-----
> > >> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> > >> Sent: Thursday, January 29, 2015 21:31 PM
> > >> To: Dexuan Cui
> > >> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> > >> driverdev- devel@linuxdriverproject.org; olaf@aepfle.de;
> > >> apw@canonical.com; jasowang@redhat.com; KY Srinivasan; Haiyang
> > >> Zhang
> > >> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> > >> HV_STATUS_INVALID_CONNECTION_ID
> > >>
> > >> Dexuan Cui <decui@microsoft.com> writes:
> > >>
> > >> > I got the hypercall error code on Hyper-V 2008 R2 when keeping
> > >> > running "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils;
> > >> > modprobe
> > hv_utils"
> > >> > in a Linux guest.
> > >> >
> > >> > Without the patch, the driver can occasionally fail to load.
> > >> >
> > >> > CC: "K. Y. Srinivasan" <kys@microsoft.com>
> > >> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > >> > ---
> > >> >  arch/x86/include/uapi/asm/hyperv.h | 1 +
> > >> >  drivers/hv/connection.c            | 9 +++++++++
> > >> >  2 files changed, 10 insertions(+)
> > >> >
> > >> > diff --git a/arch/x86/include/uapi/asm/hyperv.h
> > >> b/arch/x86/include/uapi/asm/hyperv.h
> > >> > index 90c458e..b9daffb 100644
> > >> > --- a/arch/x86/include/uapi/asm/hyperv.h
> > >> > +++ b/arch/x86/include/uapi/asm/hyperv.h
> > >> > @@ -225,6 +225,7 @@
> > >> >  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
> > >> >  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
> > >> >  #define HV_STATUS_INVALID_ALIGNMENT		4
> > >> > +#define HV_STATUS_INVALID_CONNECTION_ID		18
> > >> >  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> > >>
> > >> The gap beween 4 and 18 tells me there are other codes here ;-) Are
> > >> they all 'permanent failures'?
> > > It looks we only need to care about these error codes here.
> > >
> > > BTW, you can get all the hypercall error codes in the top level functional
> spec:
> > > http://blogs.msdn.com/b/virtual_pc_guy/archive/2014/02/17/updated-
> > hypervisor-top-level-functional-specification.aspx
> > > For this hypercall (0x005c), see "14.9.7 HvPostMessage".
> >
> > Thanks, interesting!
> >
> > Btw, HV_STATUS_INSUFFICIENT_MEMORY looks suspicious, looks like we
> can
> > hit it as well...
> >
> > I suggest we split all failures here in 2 classes:
> > 1) permanent
> > 2) worth retrying
> >
> > and treat them accordingly (no big changes, just maybe group them
> > within
> > hv_post_message() together as it is the only place where these codes
> > are being used).
> Thanks for the suggestion, Vitaly!
> I'll send out  v2.

Thanks Dexuan.

K. Y

Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Jason Wang]

On Thu, Jan 29, 2015 at 7:02 PM, Dexuan Cui <decui@microsoft.com> wrote:
> I got the hypercall error code on Hyper-V 2008 R2 when keeping running
> "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe 
> hv_utils"
> in a Linux guest.
> 
> Without the patch, the driver can occasionally fail to load.
> 
> CC: "K. Y. Srinivasan" <kys@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>  arch/x86/include/uapi/asm/hyperv.h | 1 +
>  drivers/hv/connection.c            | 9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/arch/x86/include/uapi/asm/hyperv.h 
> b/arch/x86/include/uapi/asm/hyperv.h
> index 90c458e..b9daffb 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -225,6 +225,7 @@
>  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
>  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
>  #define HV_STATUS_INVALID_ALIGNMENT		4
> +#define HV_STATUS_INVALID_CONNECTION_ID		18
>  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
>  
>  typedef struct _HV_REFERENCE_TSC_PAGE {
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index c4acd1c..8bd05f3 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
>  		ret = hv_post_message(conn_id, 1, buffer, buflen);
>  
>  		switch (ret) {
> +		case HV_STATUS_INVALID_CONNECTION_ID:
> +			/*
> +			 * We could get this if we send messages too
> +			 * frequently or the host is under low resource
> +			 * conditions: let's wait 1 more second before
> +			 * retrying the hypercall.
> +			 */

The name HV_STATUS_INVALID_CONNECTION_ID is really confusing in this 
case. Since it does not show any meaning of lacking resources. 
> +			msleep(1000);
> +			break;
>  		case HV_STATUS_INSUFFICIENT_BUFFERS:
>  			ret = -ENOMEM;

I thought host should return this error value when lacking resources?
> 
>  		case -ENOMEM:
> -- 
> 1.9.1
> 
> --
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RE: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on HV_STATUS_INVALID_CONNECTION_ID

[Dexuan Cui]

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> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Friday, January 30, 2015 10:47 AM
> To: Dexuan Cui
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com; KY
> Srinivasan; Haiyang Zhang
> Subject: Re: [PATCH 2/3] hv: vmbus_post_msg: retry the hypercall on
> HV_STATUS_INVALID_CONNECTION_ID
> 
> 
> 
> On Thu, Jan 29, 2015 at 7:02 PM, Dexuan Cui <decui@microsoft.com> wrote:
> > I got the hypercall error code on Hyper-V 2008 R2 when keeping running
> > "rmmod hv_netvsc; modprobe hv_netvsc; rmmod hv_utils; modprobe
> > hv_utils"
> > in a Linux guest.
> >
> > Without the patch, the driver can occasionally fail to load.
> >
> > CC: "K. Y. Srinivasan" <kys@microsoft.com>
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > ---
> >  arch/x86/include/uapi/asm/hyperv.h | 1 +
> >  drivers/hv/connection.c            | 9 +++++++++
> >  2 files changed, 10 insertions(+)
> >
> > diff --git a/arch/x86/include/uapi/asm/hyperv.h
> > b/arch/x86/include/uapi/asm/hyperv.h
> > index 90c458e..b9daffb 100644
> > --- a/arch/x86/include/uapi/asm/hyperv.h
> > +++ b/arch/x86/include/uapi/asm/hyperv.h
> > @@ -225,6 +225,7 @@
> >  #define HV_STATUS_INVALID_HYPERCALL_CODE	2
> >  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
> >  #define HV_STATUS_INVALID_ALIGNMENT		4
> > +#define HV_STATUS_INVALID_CONNECTION_ID		18
> >  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> >
> >  typedef struct _HV_REFERENCE_TSC_PAGE {
> > diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> > index c4acd1c..8bd05f3 100644
> > --- a/drivers/hv/connection.c
> > +++ b/drivers/hv/connection.c
> > @@ -440,6 +440,15 @@ int vmbus_post_msg(void *buffer, size_t buflen)
> >  		ret = hv_post_message(conn_id, 1, buffer, buflen);
> >
> >  		switch (ret) {
> > +		case HV_STATUS_INVALID_CONNECTION_ID:
> > +			/*
> > +			 * We could get this if we send messages too
> > +			 * frequently or the host is under low resource
> > +			 * conditions: let's wait 1 more second before
> > +			 * retrying the hypercall.
> > +			 */
> 
> The name HV_STATUS_INVALID_CONNECTION_ID is really confusing in this
> case. Since it does not show any meaning of lacking resources.
The description about the 'low host resource condition' might be not accurate.
I'll remove this part.

> > +			msleep(1000);
> > +			break;
> >  		case HV_STATUS_INSUFFICIENT_BUFFERS:
> >  			ret = -ENOMEM;
> 
> I thought host should return this error value when lacking resources?
This should be correct.

> >
> >  		case -ENOMEM:
> > --

Thanks,
-- Dexuan
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