[PATCH] vdpa: conditionally fill max max queue pair for stats

[PATCH] vdpa: conditionally fill max max queue pair for stats

[Jason Wang]

For the device without multiqueue feature, we will read 0 as
max_virtqueue_pairs from the config. So if we fill
VDPA_ATTR_DEV_NET_CFG_MAX_VQP with the value we read from the config
we will confuse the user.

Fixing this by only filling the value when multiqueue is offered by
the device so userspace can assume 1 when the attr is not provided.

Fixes: 13b00b135665c("vdpa: Add support for querying vendor statistics")
Cc: Eli Cohen <elic@nvidia.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vdpa/vdpa.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index c06c02704461..bc328197263f 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -894,7 +894,6 @@ static int vdpa_fill_stats_rec(struct vdpa_device *vdev, struct sk_buff *msg,
 {
 	struct virtio_net_config config = {};
 	u64 features;
-	u16 max_vqp;
 	u8 status;
 	int err;
 
@@ -905,15 +904,15 @@ static int vdpa_fill_stats_rec(struct vdpa_device *vdev, struct sk_buff *msg,
 	}
 	vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
 
-	max_vqp = __virtio16_to_cpu(true, config.max_virtqueue_pairs);
-	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP, max_vqp))
-		return -EMSGSIZE;
-
 	features = vdev->config->get_driver_features(vdev);
 	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES,
 			      features, VDPA_ATTR_PAD))
 		return -EMSGSIZE;
 
+	err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
+	if (err)
+		return err;
+
 	if (nla_put_u32(msg, VDPA_ATTR_DEV_QUEUE_INDEX, index))
 		return -EMSGSIZE;
 
-- 
2.25.1

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Re: [PATCH] vdpa: conditionally fill max max queue pair for stats

[Jason Wang]

On Wed, Sep 7, 2022 at 2:11 PM Eli Cohen <elic@nvidia.com> wrote:
>
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Wednesday, 7 September 2022 9:01
> > To: mst@redhat.com; jasowang@redhat.com; Eli Cohen <elic@nvidia.com>;
> > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org
> > Subject: [PATCH] vdpa: conditionally fill max max queue pair for stats
> >
> > For the device without multiqueue feature, we will read 0 as
> > max_virtqueue_pairs from the config.
> If this is the case for other vdpa vendor drivers, shouldn't we fix it there? After all,
> config->max_virtqueue_pairs should always show valid values.

Not for the case when the device doesn't offer MQ. According to the
spec, the max_virtqueue_pairs doesn't exist in this case.

>
> > So if we fill
> > VDPA_ATTR_DEV_NET_CFG_MAX_VQP with the value we read from the
> > config
> > we will confuse the user.
> >
> > Fixing this by only filling the value when multiqueue is offered by
> > the device so userspace can assume 1 when the attr is not provided.
> >
> > Fixes: 13b00b135665c("vdpa: Add support for querying vendor statistics")
> > Cc: Eli Cohen <elic@nvidia.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > ---
> >  drivers/vdpa/vdpa.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > index c06c02704461..bc328197263f 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -894,7 +894,6 @@ static int vdpa_fill_stats_rec(struct vdpa_device
> > *vdev, struct sk_buff *msg,
> >  {
> >       struct virtio_net_config config = {};
> >       u64 features;
> > -     u16 max_vqp;
> >       u8 status;
> >       int err;
> >
> > @@ -905,15 +904,15 @@ static int vdpa_fill_stats_rec(struct vdpa_device
> > *vdev, struct sk_buff *msg,
> >       }
> >       vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
> >
> > -     max_vqp = __virtio16_to_cpu(true, config.max_virtqueue_pairs);
> > -     if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> > max_vqp))
> > -             return -EMSGSIZE;
> > -
> >       features = vdev->config->get_driver_features(vdev);
> >       if (nla_put_u64_64bit(msg,
> > VDPA_ATTR_DEV_NEGOTIATED_FEATURES,
> >                             features, VDPA_ATTR_PAD))
> >               return -EMSGSIZE;
> >
> > +     err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> > +     if (err)
> > +             return err;
> > +
>
> So that means that you can't read statistics when MQ is not supported. Is this worth sacrificing?

vdpa_dev_net_mq_config_fill() will return 0 in the case of !MQ, so it
should still work.

Thanks


>
> >       if (nla_put_u32(msg, VDPA_ATTR_DEV_QUEUE_INDEX, index))
> >               return -EMSGSIZE;
> >
> > --
> > 2.25.1
>

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Re: [PATCH] vdpa: conditionally fill max max queue pair for stats

[Jason Wang]

On Wed, Sep 7, 2022 at 4:11 PM Eli Cohen <elic@nvidia.com> wrote:
>
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Wednesday, 7 September 2022 9:53
> > To: Eli Cohen <elic@nvidia.com>
> > Cc: mst@redhat.com; virtualization@lists.linux-foundation.org; linux-
> > kernel@vger.kernel.org
> > Subject: Re: [PATCH] vdpa: conditionally fill max max queue pair for stats
> >
> > On Wed, Sep 7, 2022 at 2:11 PM Eli Cohen <elic@nvidia.com> wrote:
> > >
> > > > From: Jason Wang <jasowang@redhat.com>
> > > > Sent: Wednesday, 7 September 2022 9:01
> > > > To: mst@redhat.com; jasowang@redhat.com; Eli Cohen
> > <elic@nvidia.com>;
> > > > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org
> > > > Subject: [PATCH] vdpa: conditionally fill max max queue pair for stats
> > > >
> > > > For the device without multiqueue feature, we will read 0 as
> > > > max_virtqueue_pairs from the config.
> > > If this is the case for other vdpa vendor drivers, shouldn't we fix it there?
> > After all,
> > > config->max_virtqueue_pairs should always show valid values.
> >
> > Not for the case when the device doesn't offer MQ. According to the
> > spec, the max_virtqueue_pairs doesn't exist in this case.
> >
> I see, thanks.
>
> > >
> > > > So if we fill
> > > > VDPA_ATTR_DEV_NET_CFG_MAX_VQP with the value we read from the
> > > > config
> > > > we will confuse the user.
> > > >
> > > > Fixing this by only filling the value when multiqueue is offered by
> > > > the device so userspace can assume 1 when the attr is not provided.
> > > >
> > > > Fixes: 13b00b135665c("vdpa: Add support for querying vendor
> > statistics")
> > > > Cc: Eli Cohen <elic@nvidia.com>
> > > > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > > > ---
> > > >  drivers/vdpa/vdpa.c | 9 ++++-----
> > > >  1 file changed, 4 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > > > index c06c02704461..bc328197263f 100644
> > > > --- a/drivers/vdpa/vdpa.c
> > > > +++ b/drivers/vdpa/vdpa.c
> > > > @@ -894,7 +894,6 @@ static int vdpa_fill_stats_rec(struct vdpa_device
> > > > *vdev, struct sk_buff *msg,
> > > >  {
> > > >       struct virtio_net_config config = {};
> > > >       u64 features;
> > > > -     u16 max_vqp;
> > > >       u8 status;
> > > >       int err;
> > > >
> > > > @@ -905,15 +904,15 @@ static int vdpa_fill_stats_rec(struct
> > vdpa_device
> > > > *vdev, struct sk_buff *msg,
> > > >       }
> > > >       vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
> > > >
> > > > -     max_vqp = __virtio16_to_cpu(true, config.max_virtqueue_pairs);
> > > > -     if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> > > > max_vqp))
> > > > -             return -EMSGSIZE;
> > > > -
> > > >       features = vdev->config->get_driver_features(vdev);
> > > >       if (nla_put_u64_64bit(msg,
> > > > VDPA_ATTR_DEV_NEGOTIATED_FEATURES,
> > > >                             features, VDPA_ATTR_PAD))
> > > >               return -EMSGSIZE;
> > > >
> > > > +     err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> > > > +     if (err)
> > > > +             return err;
> > > > +
> > >
> > > So that means that you can't read statistics when MQ is not supported. Is
> > this worth sacrificing?
> >
> > vdpa_dev_net_mq_config_fill() will return 0 in the case of !MQ, so it
> > should still work.
>
> Right, missed that.
>
> Reviewed-by: Eli Cohen <elic@nvidia.com>

Michael, I don't see this is merged.

Any comments for this patch?

Thanks


>
> >
> > Thanks
> >
> >
> > >
> > > >       if (nla_put_u32(msg, VDPA_ATTR_DEV_QUEUE_INDEX, index))
> > > >               return -EMSGSIZE;
> > > >
> > > > --
> > > > 2.25.1
> > >
>

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Re: [PATCH] vdpa: conditionally fill max max queue pair for stats

[Michael S. Tsirkin]

On Tue, Dec 13, 2022 at 03:12:23PM +0800, Jason Wang wrote:
> On Wed, Sep 7, 2022 at 4:11 PM Eli Cohen <elic@nvidia.com> wrote:
> >
> > > From: Jason Wang <jasowang@redhat.com>
> > > Sent: Wednesday, 7 September 2022 9:53
> > > To: Eli Cohen <elic@nvidia.com>
> > > Cc: mst@redhat.com; virtualization@lists.linux-foundation.org; linux-
> > > kernel@vger.kernel.org
> > > Subject: Re: [PATCH] vdpa: conditionally fill max max queue pair for stats
> > >
> > > On Wed, Sep 7, 2022 at 2:11 PM Eli Cohen <elic@nvidia.com> wrote:
> > > >
> > > > > From: Jason Wang <jasowang@redhat.com>
> > > > > Sent: Wednesday, 7 September 2022 9:01
> > > > > To: mst@redhat.com; jasowang@redhat.com; Eli Cohen
> > > <elic@nvidia.com>;
> > > > > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org
> > > > > Subject: [PATCH] vdpa: conditionally fill max max queue pair for stats
> > > > >
> > > > > For the device without multiqueue feature, we will read 0 as
> > > > > max_virtqueue_pairs from the config.
> > > > If this is the case for other vdpa vendor drivers, shouldn't we fix it there?
> > > After all,
> > > > config->max_virtqueue_pairs should always show valid values.
> > >
> > > Not for the case when the device doesn't offer MQ. According to the
> > > spec, the max_virtqueue_pairs doesn't exist in this case.
> > >
> > I see, thanks.
> >
> > > >
> > > > > So if we fill
> > > > > VDPA_ATTR_DEV_NET_CFG_MAX_VQP with the value we read from the
> > > > > config
> > > > > we will confuse the user.
> > > > >
> > > > > Fixing this by only filling the value when multiqueue is offered by
> > > > > the device so userspace can assume 1 when the attr is not provided.
> > > > >
> > > > > Fixes: 13b00b135665c("vdpa: Add support for querying vendor
> > > statistics")
> > > > > Cc: Eli Cohen <elic@nvidia.com>
> > > > > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > > > > ---
> > > > >  drivers/vdpa/vdpa.c | 9 ++++-----
> > > > >  1 file changed, 4 insertions(+), 5 deletions(-)
> > > > >
> > > > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > > > > index c06c02704461..bc328197263f 100644
> > > > > --- a/drivers/vdpa/vdpa.c
> > > > > +++ b/drivers/vdpa/vdpa.c
> > > > > @@ -894,7 +894,6 @@ static int vdpa_fill_stats_rec(struct vdpa_device
> > > > > *vdev, struct sk_buff *msg,
> > > > >  {
> > > > >       struct virtio_net_config config = {};
> > > > >       u64 features;
> > > > > -     u16 max_vqp;
> > > > >       u8 status;
> > > > >       int err;
> > > > >
> > > > > @@ -905,15 +904,15 @@ static int vdpa_fill_stats_rec(struct
> > > vdpa_device
> > > > > *vdev, struct sk_buff *msg,
> > > > >       }
> > > > >       vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
> > > > >
> > > > > -     max_vqp = __virtio16_to_cpu(true, config.max_virtqueue_pairs);
> > > > > -     if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> > > > > max_vqp))
> > > > > -             return -EMSGSIZE;
> > > > > -
> > > > >       features = vdev->config->get_driver_features(vdev);
> > > > >       if (nla_put_u64_64bit(msg,
> > > > > VDPA_ATTR_DEV_NEGOTIATED_FEATURES,
> > > > >                             features, VDPA_ATTR_PAD))
> > > > >               return -EMSGSIZE;
> > > > >
> > > > > +     err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> > > > > +     if (err)
> > > > > +             return err;
> > > > > +
> > > >
> > > > So that means that you can't read statistics when MQ is not supported. Is
> > > this worth sacrificing?
> > >
> > > vdpa_dev_net_mq_config_fill() will return 0 in the case of !MQ, so it
> > > should still work.
> >
> > Right, missed that.
> >
> > Reviewed-by: Eli Cohen <elic@nvidia.com>
> 
> Michael, I don't see this is merged.
> 
> Any comments for this patch?
> 
> Thanks
> 

Will be in the pull. Working on it now, it's pretty big.

> >
> > >
> > > Thanks
> > >
> > >
> > > >
> > > > >       if (nla_put_u32(msg, VDPA_ATTR_DEV_QUEUE_INDEX, index))
> > > > >               return -EMSGSIZE;
> > > > >
> > > > > --
> > > > > 2.25.1
> > > >
> >

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