diff mbox

[RFC,v2,8/8] virtio: guest driver reload for vhost-net

Message ID 1528225683-11413-9-git-send-email-wexu@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Wei Xu June 5, 2018, 7:08 p.m. UTC 
From: Wei Xu <wexu@redhat.com>

last_avail, avail_wrap_count, used_idx and used_wrap_count are
needed to support vhost-net backend, all these are either 16 or
bool variables, since state.num is 64bit wide, so here it is
possible to put them to the 'num' without introducing a new case
while handling ioctl.

Unload/Reload test has been done successfully with a patch in vhost kernel.

Signed-off-by: Wei Xu <wexu@redhat.com>
---
 hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

Comments

Jason Wang June 6, 2018, 3:48 a.m. UTC | #1 
On 2018年06月06日 03:08, wexu@redhat.com wrote:
> From: Wei Xu <wexu@redhat.com>
>
> last_avail, avail_wrap_count, used_idx and used_wrap_count are
> needed to support vhost-net backend, all these are either 16 or
> bool variables, since state.num is 64bit wide, so here it is
> possible to put them to the 'num' without introducing a new case
> while handling ioctl.
>
> Unload/Reload test has been done successfully with a patch in vhost kernel.

You need a patch to enable vhost.

And I think you can only do it for vhost-kenrel now since vhost-user 
protocol needs some extension I believe.

>
> Signed-off-by: Wei Xu <wexu@redhat.com>
> ---
>   hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
>   1 file changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 4543974..153f6d7 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2862,33 +2862,59 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
>       }
>   }
>   
> -uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
> +uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>   {
> -    return vdev->vq[n].last_avail_idx;
> +    uint64_t num;
> +
> +    num = vdev->vq[n].last_avail_idx;
> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> +        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
> +        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
> +        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;

So s.num is 32bit, I don't think this can even work.

Thanks

> +    }
> +
> +    return num;
>   }
>   
> -void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
> +void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint64_t num)
>   {
> -    vdev->vq[n].last_avail_idx = idx;
> -    vdev->vq[n].shadow_avail_idx = idx;
> +    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx = (uint16_t)(num);
> +
> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> +        vdev->vq[n].avail_wrap_counter = (uint16_t)(num >> 16);
> +        vdev->vq[n].used_idx = (uint16_t)(num >> 32);
> +        vdev->vq[n].used_wrap_counter = (uint16_t)(num >> 48);
> +    }
>   }
>   
>   void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
>   {
>       rcu_read_lock();
> -    if (vdev->vq[n].vring.desc) {
> +    if (!vdev->vq[n].vring.desc) {
> +        goto out;
> +    }
> +
> +    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>           vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]);
> -        vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
>       }
> +    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
> +
> +out:
>       rcu_read_unlock();
>   }
>   
>   void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
>   {
>       rcu_read_lock();
> -    if (vdev->vq[n].vring.desc) {
> +    if (!vdev->vq[n].vring.desc) {
> +        goto out;
> +    }
> +
> +    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>           vdev->vq[n].used_idx = vring_used_idx(&vdev->vq[n]);
>       }
> +
> +out:
>       rcu_read_unlock();
>   }
>
Wei Xu June 19, 2018, 7:53 a.m. UTC | #2 
On Wed, Jun 06, 2018 at 11:48:19AM +0800, Jason Wang wrote:
> 
> 
> On 2018年06月06日 03:08, wexu@redhat.com wrote:
> >From: Wei Xu <wexu@redhat.com>
> >
> >last_avail, avail_wrap_count, used_idx and used_wrap_count are
> >needed to support vhost-net backend, all these are either 16 or
> >bool variables, since state.num is 64bit wide, so here it is
> >possible to put them to the 'num' without introducing a new case
> >while handling ioctl.
> >
> >Unload/Reload test has been done successfully with a patch in vhost kernel.
> 
> You need a patch to enable vhost.
> 
> And I think you can only do it for vhost-kenrel now since vhost-user
> protocol needs some extension I believe.

OK.

> 
> >
> >Signed-off-by: Wei Xu <wexu@redhat.com>
> >---
> >  hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
> >  1 file changed, 34 insertions(+), 8 deletions(-)
> >
> >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >index 4543974..153f6d7 100644
> >--- a/hw/virtio/virtio.c
> >+++ b/hw/virtio/virtio.c
> >@@ -2862,33 +2862,59 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
> >      }
> >  }
> >-uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
> >+uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
> >  {
> >-    return vdev->vq[n].last_avail_idx;
> >+    uint64_t num;
> >+
> >+    num = vdev->vq[n].last_avail_idx;
> >+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >+        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
> >+        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
> >+        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
> 
> So s.num is 32bit, I don't think this can even work.

I mistakenly checked out s.num is 64bit, will add a new case in next version.

Wei

> 
> Thanks
> 
> >+    }
> >+
> >+    return num;
> >  }
> >-void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
> >+void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint64_t num)
> >  {
> >-    vdev->vq[n].last_avail_idx = idx;
> >-    vdev->vq[n].shadow_avail_idx = idx;
> >+    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx = (uint16_t)(num);
> >+
> >+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >+        vdev->vq[n].avail_wrap_counter = (uint16_t)(num >> 16);
> >+        vdev->vq[n].used_idx = (uint16_t)(num >> 32);
> >+        vdev->vq[n].used_wrap_counter = (uint16_t)(num >> 48);
> >+    }
> >  }
> >  void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
> >  {
> >      rcu_read_lock();
> >-    if (vdev->vq[n].vring.desc) {
> >+    if (!vdev->vq[n].vring.desc) {
> >+        goto out;
> >+    }
> >+
> >+    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >          vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]);
> >-        vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
> >      }
> >+    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
> >+
> >+out:
> >      rcu_read_unlock();
> >  }
> >  void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
> >  {
> >      rcu_read_lock();
> >-    if (vdev->vq[n].vring.desc) {
> >+    if (!vdev->vq[n].vring.desc) {
> >+        goto out;
> >+    }
> >+
> >+    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> >          vdev->vq[n].used_idx = vring_used_idx(&vdev->vq[n]);
> >      }
> >+
> >+out:
> >      rcu_read_unlock();
> >  }
>
Maxime Coquelin Sept. 20, 2018, 8:39 p.m. UTC | #3 
Hi Wei, Jason,

On 06/19/2018 09:53 AM, Wei Xu wrote:
> On Wed, Jun 06, 2018 at 11:48:19AM +0800, Jason Wang wrote:
>>
>>
>> On 2018年06月06日 03:08, wexu@redhat.com wrote:
>>> From: Wei Xu <wexu@redhat.com>
>>>
>>> last_avail, avail_wrap_count, used_idx and used_wrap_count are
>>> needed to support vhost-net backend, all these are either 16 or
>>> bool variables, since state.num is 64bit wide, so here it is
>>> possible to put them to the 'num' without introducing a new case
>>> while handling ioctl.
>>>
>>> Unload/Reload test has been done successfully with a patch in vhost kernel.
>>
>> You need a patch to enable vhost.
>>
>> And I think you can only do it for vhost-kenrel now since vhost-user
>> protocol needs some extension I believe.
> 
> OK.
> 
>>
>>>
>>> Signed-off-by: Wei Xu <wexu@redhat.com>
>>> ---
>>>   hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
>>>   1 file changed, 34 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>> index 4543974..153f6d7 100644
>>> --- a/hw/virtio/virtio.c
>>> +++ b/hw/virtio/virtio.c
>>> @@ -2862,33 +2862,59 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
>>>       }
>>>   }
>>> -uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>> +uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>>   {
>>> -    return vdev->vq[n].last_avail_idx;
>>> +    uint64_t num;
>>> +
>>> +    num = vdev->vq[n].last_avail_idx;
>>> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>> +        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
>>> +        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
>>> +        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
>>
>> So s.num is 32bit, I don't think this can even work.
> 
> I mistakenly checked out s.num is 64bit, will add a new case in next version.

Wouldn't be enough to just get/set avail_wrap_counter?
Something like this so that it fits into 32 bits:
     if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
         num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 31;
     }


Regards,
Maxime

> 
> Wei
> 
>>
>> Thanks
>>
>>> +    }
>>> +
>>> +    return num;
>>>   }
>>> -void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
>>> +void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint64_t num)
>>>   {
>>> -    vdev->vq[n].last_avail_idx = idx;
>>> -    vdev->vq[n].shadow_avail_idx = idx;
>>> +    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx = (uint16_t)(num);
>>> +
>>> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>> +        vdev->vq[n].avail_wrap_counter = (uint16_t)(num >> 16);
>>> +        vdev->vq[n].used_idx = (uint16_t)(num >> 32);
>>> +        vdev->vq[n].used_wrap_counter = (uint16_t)(num >> 48);
>>> +    }
>>>   }
>>>   void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
>>>   {
>>>       rcu_read_lock();
>>> -    if (vdev->vq[n].vring.desc) {
>>> +    if (!vdev->vq[n].vring.desc) {
>>> +        goto out;
>>> +    }
>>> +
>>> +    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>>           vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]);
>>> -        vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
>>>       }
>>> +    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
>>> +
>>> +out:
>>>       rcu_read_unlock();
>>>   }
>>>   void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
>>>   {
>>>       rcu_read_lock();
>>> -    if (vdev->vq[n].vring.desc) {
>>> +    if (!vdev->vq[n].vring.desc) {
>>> +        goto out;
>>> +    }
>>> +
>>> +    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>>           vdev->vq[n].used_idx = vring_used_idx(&vdev->vq[n]);
>>>       }
>>> +
>>> +out:
>>>       rcu_read_unlock();
>>>   }
>>
>
Jason Wang Sept. 21, 2018, 2:33 a.m. UTC | #4 
On 2018年09月21日 04:39, Maxime Coquelin wrote:
> Hi Wei, Jason,
>
> On 06/19/2018 09:53 AM, Wei Xu wrote:
>> On Wed, Jun 06, 2018 at 11:48:19AM +0800, Jason Wang wrote:
>>>
>>>
>>> On 2018年06月06日 03:08, wexu@redhat.com wrote:
>>>> From: Wei Xu <wexu@redhat.com>
>>>>
>>>> last_avail, avail_wrap_count, used_idx and used_wrap_count are
>>>> needed to support vhost-net backend, all these are either 16 or
>>>> bool variables, since state.num is 64bit wide, so here it is
>>>> possible to put them to the 'num' without introducing a new case
>>>> while handling ioctl.
>>>>
>>>> Unload/Reload test has been done successfully with a patch in vhost 
>>>> kernel.
>>>
>>> You need a patch to enable vhost.
>>>
>>> And I think you can only do it for vhost-kenrel now since vhost-user
>>> protocol needs some extension I believe.
>>
>> OK.
>>
>>>
>>>>
>>>> Signed-off-by: Wei Xu <wexu@redhat.com>
>>>> ---
>>>>   hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
>>>>   1 file changed, 34 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>>> index 4543974..153f6d7 100644
>>>> --- a/hw/virtio/virtio.c
>>>> +++ b/hw/virtio/virtio.c
>>>> @@ -2862,33 +2862,59 @@ hwaddr 
>>>> virtio_queue_get_used_size(VirtIODevice *vdev, int n)
>>>>       }
>>>>   }
>>>> -uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>>> +uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>>>   {
>>>> -    return vdev->vq[n].last_avail_idx;
>>>> +    uint64_t num;
>>>> +
>>>> +    num = vdev->vq[n].last_avail_idx;
>>>> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>>> +        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
>>>> +        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
>>>> +        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
>>>
>>> So s.num is 32bit, I don't think this can even work.
>>
>> I mistakenly checked out s.num is 64bit, will add a new case in next 
>> version.
>
> Wouldn't be enough to just get/set avail_wrap_counter?
> Something like this so that it fits into 32 bits:
>     if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>         num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 31;
>     }
>
>
> Regards,
> Maxime

Yes, actually, that's what I did for vhost kernel 
(https://github.com/jasowang/net/blob/packed-host/drivers/vhost/vhost.c#L1418)

Thanks
Maxime Coquelin Sept. 21, 2018, 7:30 a.m. UTC | #5 
On 09/21/2018 04:33 AM, Jason Wang wrote:
> 
> 
> On 2018年09月21日 04:39, Maxime Coquelin wrote:
>> Hi Wei, Jason,
>>
>> On 06/19/2018 09:53 AM, Wei Xu wrote:
>>> On Wed, Jun 06, 2018 at 11:48:19AM +0800, Jason Wang wrote:
>>>>
>>>>
>>>> On 2018年06月06日 03:08, wexu@redhat.com wrote:
>>>>> From: Wei Xu <wexu@redhat.com>
>>>>>
>>>>> last_avail, avail_wrap_count, used_idx and used_wrap_count are
>>>>> needed to support vhost-net backend, all these are either 16 or
>>>>> bool variables, since state.num is 64bit wide, so here it is
>>>>> possible to put them to the 'num' without introducing a new case
>>>>> while handling ioctl.
>>>>>
>>>>> Unload/Reload test has been done successfully with a patch in vhost 
>>>>> kernel.
>>>>
>>>> You need a patch to enable vhost.
>>>>
>>>> And I think you can only do it for vhost-kenrel now since vhost-user
>>>> protocol needs some extension I believe.
>>>
>>> OK.
>>>
>>>>
>>>>>
>>>>> Signed-off-by: Wei Xu <wexu@redhat.com>
>>>>> ---
>>>>>   hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
>>>>>   1 file changed, 34 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>>>> index 4543974..153f6d7 100644
>>>>> --- a/hw/virtio/virtio.c
>>>>> +++ b/hw/virtio/virtio.c
>>>>> @@ -2862,33 +2862,59 @@ hwaddr 
>>>>> virtio_queue_get_used_size(VirtIODevice *vdev, int n)
>>>>>       }
>>>>>   }
>>>>> -uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>>>> +uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
>>>>>   {
>>>>> -    return vdev->vq[n].last_avail_idx;
>>>>> +    uint64_t num;
>>>>> +
>>>>> +    num = vdev->vq[n].last_avail_idx;
>>>>> +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>>>> +        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
>>>>> +        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
>>>>> +        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
>>>>
>>>> So s.num is 32bit, I don't think this can even work.
>>>
>>> I mistakenly checked out s.num is 64bit, will add a new case in next 
>>> version.
>>
>> Wouldn't be enough to just get/set avail_wrap_counter?
>> Something like this so that it fits into 32 bits:
>>     if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
>>         num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 31;
>>     }
>>
>>
>> Regards,
>> Maxime
> 
> Yes, actually, that's what I did for vhost kernel 
> (https://github.com/jasowang/net/blob/packed-host/drivers/vhost/vhost.c#L1418) 

Oh yes, I forgot on what I based my implementation on.
Wei, Michael, do you agree with this? I will need to merge the Vhost
patch in DPDK in the coming two weeks.

Regards,
Maxime

> 
> Thanks
Michael S. Tsirkin Sept. 21, 2018, 6:23 p.m. UTC | #6 
On Fri, Sep 21, 2018 at 09:30:26AM +0200, Maxime Coquelin wrote:
> 
> 
> On 09/21/2018 04:33 AM, Jason Wang wrote:
> > 
> > 
> > On 2018年09月21日 04:39, Maxime Coquelin wrote:
> > > Hi Wei, Jason,
> > > 
> > > On 06/19/2018 09:53 AM, Wei Xu wrote:
> > > > On Wed, Jun 06, 2018 at 11:48:19AM +0800, Jason Wang wrote:
> > > > > 
> > > > > 
> > > > > On 2018年06月06日 03:08, wexu@redhat.com wrote:
> > > > > > From: Wei Xu <wexu@redhat.com>
> > > > > > 
> > > > > > last_avail, avail_wrap_count, used_idx and used_wrap_count are
> > > > > > needed to support vhost-net backend, all these are either 16 or
> > > > > > bool variables, since state.num is 64bit wide, so here it is
> > > > > > possible to put them to the 'num' without introducing a new case
> > > > > > while handling ioctl.
> > > > > > 
> > > > > > Unload/Reload test has been done successfully with a
> > > > > > patch in vhost kernel.
> > > > > 
> > > > > You need a patch to enable vhost.
> > > > > 
> > > > > And I think you can only do it for vhost-kenrel now since vhost-user
> > > > > protocol needs some extension I believe.
> > > > 
> > > > OK.
> > > > 
> > > > > 
> > > > > > 
> > > > > > Signed-off-by: Wei Xu <wexu@redhat.com>
> > > > > > ---
> > > > > >   hw/virtio/virtio.c | 42 ++++++++++++++++++++++++++++++++++--------
> > > > > >   1 file changed, 34 insertions(+), 8 deletions(-)
> > > > > > 
> > > > > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > > > > > index 4543974..153f6d7 100644
> > > > > > --- a/hw/virtio/virtio.c
> > > > > > +++ b/hw/virtio/virtio.c
> > > > > > @@ -2862,33 +2862,59 @@ hwaddr
> > > > > > virtio_queue_get_used_size(VirtIODevice *vdev, int n)
> > > > > >       }
> > > > > >   }
> > > > > > -uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
> > > > > > +uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
> > > > > >   {
> > > > > > -    return vdev->vq[n].last_avail_idx;
> > > > > > +    uint64_t num;
> > > > > > +
> > > > > > +    num = vdev->vq[n].last_avail_idx;
> > > > > > +    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> > > > > > +        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
> > > > > > +        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
> > > > > > +        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
> > > > > 
> > > > > So s.num is 32bit, I don't think this can even work.
> > > > 
> > > > I mistakenly checked out s.num is 64bit, will add a new case in
> > > > next version.
> > > 
> > > Wouldn't be enough to just get/set avail_wrap_counter?
> > > Something like this so that it fits into 32 bits:
> > >     if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> > >         num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 31;
> > >     }
> > > 
> > > 
> > > Regards,
> > > Maxime
> > 
> > Yes, actually, that's what I did for vhost kernel (https://github.com/jasowang/net/blob/packed-host/drivers/vhost/vhost.c#L1418)
> 
> Oh yes, I forgot on what I based my implementation on.
> Wei, Michael, do you agree with this? I will need to merge the Vhost
> patch in DPDK in the coming two weeks.
> 
> Regards,
> Maxime

It looks reasonable to me.

> > 
> > Thanks
diff mbox

Patch

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 4543974..153f6d7 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2862,33 +2862,59 @@  hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n)
     }
 }
 
-uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
+uint64_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n)
 {
-    return vdev->vq[n].last_avail_idx;
+    uint64_t num;
+
+    num = vdev->vq[n].last_avail_idx;
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        num |= ((uint64_t)vdev->vq[n].avail_wrap_counter) << 16;
+        num |= ((uint64_t)vdev->vq[n].used_idx) << 32;
+        num |= ((uint64_t)vdev->vq[n].used_wrap_counter) << 48;
+    }
+
+    return num;
 }
 
-void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
+void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint64_t num)
 {
-    vdev->vq[n].last_avail_idx = idx;
-    vdev->vq[n].shadow_avail_idx = idx;
+    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx = (uint16_t)(num);
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
+        vdev->vq[n].avail_wrap_counter = (uint16_t)(num >> 16);
+        vdev->vq[n].used_idx = (uint16_t)(num >> 32);
+        vdev->vq[n].used_wrap_counter = (uint16_t)(num >> 48);
+    }
 }
 
 void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n)
 {
     rcu_read_lock();
-    if (vdev->vq[n].vring.desc) {
+    if (!vdev->vq[n].vring.desc) {
+        goto out;
+    }
+
+    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
         vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]);
-        vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
     }
+    vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx;
+
+out:
     rcu_read_unlock();
 }
 
 void virtio_queue_update_used_idx(VirtIODevice *vdev, int n)
 {
     rcu_read_lock();
-    if (vdev->vq[n].vring.desc) {
+    if (!vdev->vq[n].vring.desc) {
+        goto out;
+    }
+
+    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
         vdev->vq[n].used_idx = vring_used_idx(&vdev->vq[n]);
     }
+
+out:
     rcu_read_unlock();
 }