[PATCH net v2 0/3] vsock/virtio: enable VQs early on probe and finish the setup before using them

[PATCH net v2 0/3] vsock/virtio: enable VQs early on probe and finish the setup before using them

[Stefano Garzarella]

The first patch fixes a virtio-spec violation. The other two patches
complete the driver configuration before using the VQs in the probe.

The patch order should simplify backporting in stable branches.

v2:
- patch 1 is not changed from v1
- added 2 patches to complete the driver configuration before using the
  VQs in the probe [MST]

v1: https://lore.kernel.org/netdev/20220322103823.83411-1-sgarzare@redhat.com/

Stefano Garzarella (3):
  vsock/virtio: enable VQs early on probe
  vsock/virtio: initialize vdev->priv before using VQs
  vsock/virtio: read the negotiated features before using VQs

 net/vmw_vsock/virtio_transport.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

-- 
2.35.1

[PATCH net v2 1/3] vsock/virtio: enable VQs early on probe

[Stefano Garzarella]

virtio spec requires drivers to set DRIVER_OK before using VQs.
This is set automatically after probe returns, but virtio-vsock
driver uses VQs in the probe function to fill rx and event VQs
with new buffers.

Let's fix this, calling virtio_device_ready() before using VQs
in the probe function.

Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 net/vmw_vsock/virtio_transport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 5afc194a58bb..b1962f8cd502 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 
+	virtio_device_ready(vdev);
+
 	mutex_lock(&vsock->tx_lock);
 	vsock->tx_run = true;
 	mutex_unlock(&vsock->tx_lock);
-- 
2.35.1

Re: [PATCH net v2 1/3] vsock/virtio: enable VQs early on probe

[Stefan Hajnoczi]

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On Wed, Mar 23, 2022 at 09:49:52AM +0100, Stefano Garzarella wrote:
> virtio spec requires drivers to set DRIVER_OK before using VQs.
> This is set automatically after probe returns, but virtio-vsock
> driver uses VQs in the probe function to fill rx and event VQs
> with new buffers.
> 
> Let's fix this, calling virtio_device_ready() before using VQs
> in the probe function.
> 
> Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko")
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  net/vmw_vsock/virtio_transport.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index 5afc194a58bb..b1962f8cd502 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>  	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
>  	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
>  
> +	virtio_device_ready(vdev);

Can rx and event virtqueue interrupts be lost if they occur before we
assign vdev->priv later in virtio_vsock_probe()?

Stefan

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Re: [PATCH net v2 1/3] vsock/virtio: enable VQs early on probe

[Stefano Garzarella]

On Wed, Mar 23, 2022 at 01:44:42PM +0000, Stefan Hajnoczi wrote:
>On Wed, Mar 23, 2022 at 09:49:52AM +0100, Stefano Garzarella wrote:
>> virtio spec requires drivers to set DRIVER_OK before using VQs.
>> This is set automatically after probe returns, but virtio-vsock
>> driver uses VQs in the probe function to fill rx and event VQs
>> with new buffers.
>>
>> Let's fix this, calling virtio_device_ready() before using VQs
>> in the probe function.
>>
>> Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko")
>> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>> ---
>>  net/vmw_vsock/virtio_transport.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>> index 5afc194a58bb..b1962f8cd502 100644
>> --- a/net/vmw_vsock/virtio_transport.c
>> +++ b/net/vmw_vsock/virtio_transport.c
>> @@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>>  	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
>>  	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
>>
>> +	virtio_device_ready(vdev);
>
>Can rx and event virtqueue interrupts be lost if they occur before we
>assign vdev->priv later in virtio_vsock_probe()?

Yep, as Michael suggested I'll fix the patch order in the next version.

Thanks,
Stefano

[PATCH net v2 2/3] vsock/virtio: initialize vdev->priv before using VQs

[Stefano Garzarella]

When we fill VQs with empty buffers and kick the host, it may send
an interrupt. `vdev->priv` must be initialized before this since it
is used in the virtqueue callback.

Fixes: 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock")
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 net/vmw_vsock/virtio_transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index b1962f8cd502..fff67ad39087 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -622,6 +622,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 
+	vdev->priv = vsock;
 	virtio_device_ready(vdev);
 
 	mutex_lock(&vsock->tx_lock);
@@ -641,7 +642,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
 		vsock->seqpacket_allow = true;
 
-	vdev->priv = vsock;
 	rcu_assign_pointer(the_virtio_vsock, vsock);
 
 	mutex_unlock(&the_virtio_vsock_mutex);
-- 
2.35.1

Re: [PATCH net v2 2/3] vsock/virtio: initialize vdev->priv before using VQs

[Stefan Hajnoczi]

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On Wed, Mar 23, 2022 at 09:49:53AM +0100, Stefano Garzarella wrote:
> When we fill VQs with empty buffers and kick the host, it may send
> an interrupt. `vdev->priv` must be initialized before this since it
> is used in the virtqueue callback.
> 
> Fixes: 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock")
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  net/vmw_vsock/virtio_transport.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index b1962f8cd502..fff67ad39087 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -622,6 +622,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>  	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
>  	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
>  
> +	vdev->priv = vsock;
>  	virtio_device_ready(vdev);

Doh, patch order got me. :)

Stefan

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[PATCH net v2 3/3] vsock/virtio: read the negotiated features before using VQs

[Stefano Garzarella]

Complete the driver configuration, reading the negotiated features,
before using the VQs and tell the device that the driver is ready in
the virtio_vsock_probe().

Fixes: 53efbba12cc7 ("virtio/vsock: enable SEQPACKET for transport")
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 net/vmw_vsock/virtio_transport.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index fff67ad39087..1244e7cf585b 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -622,6 +622,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 
+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
+		vsock->seqpacket_allow = true;
+
 	vdev->priv = vsock;
 	virtio_device_ready(vdev);
 
@@ -639,9 +642,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	vsock->event_run = true;
 	mutex_unlock(&vsock->event_lock);
 
-	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
-		vsock->seqpacket_allow = true;
-
 	rcu_assign_pointer(the_virtio_vsock, vsock);
 
 	mutex_unlock(&the_virtio_vsock_mutex);
-- 
2.35.1

Re: [PATCH net v2 3/3] vsock/virtio: read the negotiated features before using VQs

[Stefan Hajnoczi]

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On Wed, Mar 23, 2022 at 09:49:54AM +0100, Stefano Garzarella wrote:
> Complete the driver configuration, reading the negotiated features,
> before using the VQs and tell the device that the driver is ready in
> the virtio_vsock_probe().
> 
> Fixes: 53efbba12cc7 ("virtio/vsock: enable SEQPACKET for transport")
> Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  net/vmw_vsock/virtio_transport.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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Re: [PATCH net v2 0/3] vsock/virtio: enable VQs early on probe and finish the setup before using them

[Michael S. Tsirkin]

On Wed, Mar 23, 2022 at 09:49:51AM +0100, Stefano Garzarella wrote:
> The first patch fixes a virtio-spec violation. The other two patches
> complete the driver configuration before using the VQs in the probe.
> 
> The patch order should simplify backporting in stable branches.

Ok but I think the order is wrong. It should be 2-3-1,
otherwise bisect can pick just 1 and it will have
the issues previous reviw pointed out.



> v2:
> - patch 1 is not changed from v1
> - added 2 patches to complete the driver configuration before using the
>   VQs in the probe [MST]
> 
> v1: https://lore.kernel.org/netdev/20220322103823.83411-1-sgarzare@redhat.com/
> 
> Stefano Garzarella (3):
>   vsock/virtio: enable VQs early on probe
>   vsock/virtio: initialize vdev->priv before using VQs
>   vsock/virtio: read the negotiated features before using VQs
> 
>  net/vmw_vsock/virtio_transport.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> -- 
> 2.35.1

Re: [PATCH net v2 0/3] vsock/virtio: enable VQs early on probe and finish the setup before using them

[Stefano Garzarella]

On Wed, Mar 23, 2022 at 09:22:02AM -0400, Michael S. Tsirkin wrote:
>On Wed, Mar 23, 2022 at 09:49:51AM +0100, Stefano Garzarella wrote:
>> The first patch fixes a virtio-spec violation. The other two patches
>> complete the driver configuration before using the VQs in the probe.
>>
>> The patch order should simplify backporting in stable branches.
>
>Ok but I think the order is wrong. It should be 2-3-1,
>otherwise bisect can pick just 1 and it will have
>the issues previous reviw pointed out.

Right, I prioritized simplifying the backport, but obviously 
bisectability is priority!

I'll send v3 changing the order in 2-3-1

Thanks,
Stefano