Re: [RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012 hosts

[Stephen Hemminger]

On Tue, 23 Jan 2018 10:34:03 +0100
Mohammed Gamal  wrote:

> Commit 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split") introduced
> a regression that caused VMs not to shutdown after netvsc_device_remove() is
> called. This is caused by GPADL teardown sequence change, and while that was 
> necessary to fix issues with Win2016 hosts, it did introduce a regression for
> earlier versions.
> 
> Prior to commit 0cf737808 the call sequence in netvsc_device_remove() was as 
> follows (as implemented in netvsc_destroy_buf()):
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Teardown receive buffer GPADL
> 3- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 4- Teardown send buffer GPADL
> 5- Close vmbus
> 
> This didn't work for WS2016 hosts. Commit 0cf737808 split netvsc_destroy_buf()
> into two functions and rearranged the order as follows
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 3- Close vmbus
> 4- Teardown receive buffer GPADL
> 5- Teardown send buffer GPADL
> 
> That worked well for WS2016 hosts, but for WS2012 hosts it prevented VMs from
> shutting down. 
> 
> This patch series works around this problem. The first patch splits
> netvsc_revoke_buf() and netvsc_teardown_gpadl() into two finer grained
> functions for tearing down send and receive buffers individally. The second 
> patch
> uses the finer grained functions to implement the teardown sequence according 
> to
> the host's version. We keep the behavior introduced in 0cf737808ae7 for 
> Windows
> 2016 hosts, while we re-introduce the old sequence for earlier verions.
> 
> Mohammed Gamal (2):
>   hv_netvsc: Split netvsc_revoke_buf() and netvsc_teardown_gpadl()
>   hv_netvsc: Change GPADL teardown order according to Hyper-V version
> 
>  drivers/net/hyperv/netvsc.c | 50 
> +
>  1 file changed, 42 insertions(+), 8 deletions(-)
> 

What I am experimenting with is sending an NDIS_RESET (instead of setting 
packet filter)
as part of the close processing. This seems more like what the description of 
what Windows
driver does and matches my reading of the public RNDIS specification.
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Re: [RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012 hosts

[Stephen Hemminger]

On Tue, 23 Jan 2018 10:34:03 +0100
Mohammed Gamal  wrote:

> Commit 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split") introduced
> a regression that caused VMs not to shutdown after netvsc_device_remove() is
> called. This is caused by GPADL teardown sequence change, and while that was 
> necessary to fix issues with Win2016 hosts, it did introduce a regression for
> earlier versions.
> 
> Prior to commit 0cf737808 the call sequence in netvsc_device_remove() was as 
> follows (as implemented in netvsc_destroy_buf()):
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Teardown receive buffer GPADL
> 3- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 4- Teardown send buffer GPADL
> 5- Close vmbus
> 
> This didn't work for WS2016 hosts. Commit 0cf737808 split netvsc_destroy_buf()
> into two functions and rearranged the order as follows
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 3- Close vmbus
> 4- Teardown receive buffer GPADL
> 5- Teardown send buffer GPADL
> 
> That worked well for WS2016 hosts, but for WS2012 hosts it prevented VMs from
> shutting down. 
> 
> This patch series works around this problem. The first patch splits
> netvsc_revoke_buf() and netvsc_teardown_gpadl() into two finer grained
> functions for tearing down send and receive buffers individally. The second 
> patch
> uses the finer grained functions to implement the teardown sequence according 
> to
> the host's version. We keep the behavior introduced in 0cf737808ae7 for 
> Windows
> 2016 hosts, while we re-introduce the old sequence for earlier verions.
> 
> Mohammed Gamal (2):
>   hv_netvsc: Split netvsc_revoke_buf() and netvsc_teardown_gpadl()
>   hv_netvsc: Change GPADL teardown order according to Hyper-V version
> 
>  drivers/net/hyperv/netvsc.c | 50 
> +
>  1 file changed, 42 insertions(+), 8 deletions(-)
> 

The problem the original commit was trying to solve was actions in flight
in the receive buffer on shutdown. Having different ordering for each version 
of Hyper-V
seems unnecessary. There should be a way to get a stable sequence here.

Let me see if I can shake more information out of the Windows team to see what
the handshake on the other side is. Let's not apply this until then.
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RE: [RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012 hosts

[Haiyang Zhang]

> -Original Message-
> From: Mohammed Gamal [mailto:mga...@redhat.com]
> Sent: Tuesday, January 23, 2018 4:34 AM
> To: net...@vger.kernel.org
> Cc: linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; KY
> Srinivasan <k...@microsoft.com>; Haiyang Zhang <haiya...@microsoft.com>;
> Stephen Hemminger <sthem...@microsoft.com>; vkuzn...@redhat.com;
> cav...@redhat.com; ot...@redhat.com; Mohammed Gamal
> <mga...@redhat.com>
> Subject: [RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012
> hosts
> 
> Commit 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split")
> introduced a regression that caused VMs not to shutdown after
> netvsc_device_remove() is called. This is caused by GPADL teardown
> sequence change, and while that was necessary to fix issues with Win2016
> hosts, it did introduce a regression for earlier versions.
> 
> Prior to commit 0cf737808 the call sequence in netvsc_device_remove() was
> as follows (as implemented in netvsc_destroy_buf()):
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Teardown receive buffer GPADL
> 3- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 4- Teardown send buffer GPADL
> 5- Close vmbus
> 
> This didn't work for WS2016 hosts. Commit 0cf737808 split
> netvsc_destroy_buf() into two functions and rearranged the order as follows
> 1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
> 2- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
> 3- Close vmbus
> 4- Teardown receive buffer GPADL
> 5- Teardown send buffer GPADL
> 
> That worked well for WS2016 hosts, but for WS2012 hosts it prevented VMs
> from shutting down.
> 
> This patch series works around this problem. The first patch splits
> netvsc_revoke_buf() and netvsc_teardown_gpadl() into two finer grained
> functions for tearing down send and receive buffers individally. The second
> patch uses the finer grained functions to implement the teardown sequence
> according to the host's version. We keep the behavior introduced in
> 0cf737808ae7 for Windows
> 2016 hosts, while we re-introduce the old sequence for earlier verions.
> 
> Mohammed Gamal (2):
>   hv_netvsc: Split netvsc_revoke_buf() and netvsc_teardown_gpadl()
>   hv_netvsc: Change GPADL teardown order according to Hyper-V version
> 
>  drivers/net/hyperv/netvsc.c | 50
> +
>  1 file changed, 42 insertions(+), 8 deletions(-)

Thank you for the patches. We are testing them internally.

- Haiyang
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[RFC PATCH 0/2] hv_netvsc: Fix shutdown regression on Win2012 hosts

[Mohammed Gamal]

Commit 0cf737808ae7 ("hv_netvsc: netvsc_teardown_gpadl() split") introduced
a regression that caused VMs not to shutdown after netvsc_device_remove() is
called. This is caused by GPADL teardown sequence change, and while that was 
necessary to fix issues with Win2016 hosts, it did introduce a regression for
earlier versions.

Prior to commit 0cf737808 the call sequence in netvsc_device_remove() was as 
follows (as implemented in netvsc_destroy_buf()):
1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
2- Teardown receive buffer GPADL
3- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
4- Teardown send buffer GPADL
5- Close vmbus

This didn't work for WS2016 hosts. Commit 0cf737808 split netvsc_destroy_buf()
into two functions and rearranged the order as follows
1- Send NVSP_MSG1_TYPE_REVOKE_RECV_BUF message
2- Send NVSP_MSG1_TYPE_REVOKE_SEND_BUF message
3- Close vmbus
4- Teardown receive buffer GPADL
5- Teardown send buffer GPADL

That worked well for WS2016 hosts, but for WS2012 hosts it prevented VMs from
shutting down. 

This patch series works around this problem. The first patch splits
netvsc_revoke_buf() and netvsc_teardown_gpadl() into two finer grained
functions for tearing down send and receive buffers individally. The second 
patch
uses the finer grained functions to implement the teardown sequence according to
the host's version. We keep the behavior introduced in 0cf737808ae7 for Windows
2016 hosts, while we re-introduce the old sequence for earlier verions.

Mohammed Gamal (2):
  hv_netvsc: Split netvsc_revoke_buf() and netvsc_teardown_gpadl()
  hv_netvsc: Change GPADL teardown order according to Hyper-V version

 drivers/net/hyperv/netvsc.c | 50 +
 1 file changed, 42 insertions(+), 8 deletions(-)

-- 
1.8.3.1

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