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[RFC V1 07/13] vhost-vdpa: flush workers on suspend

Steve Sistare posted 13 patches 2 years, 1 month ago
There is a newer version of this series
[RFC V1 07/13] vhost-vdpa: flush workers on suspend
Posted by Steve Sistare 2 years, 1 month ago 
To pass ownership of a live vdpa device to a new process, the user
suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
mm.  Flush workers in suspend to guarantee that no worker sees the new
mm and old VA in between.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 drivers/vhost/vdpa.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 8fe1562d24af..9673e8e20d11 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
 {
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_dev *vdev = &v->vdev;
 
 	if (!ops->suspend)
 		return -EOPNOTSUPP;
 
+	if (vdev->use_worker)
+		vhost_dev_flush(vdev);
+
 	return ops->suspend(vdpa);
 }
 
-- 
2.39.3
Re: [RFC V1 07/13] vhost-vdpa: flush workers on suspend
Posted by Jason Wang 2 years, 1 month ago 
On Thu, Jan 11, 2024 at 4:40 AM Steve Sistare <steven.sistare@oracle.com> wrote:
>
> To pass ownership of a live vdpa device to a new process, the user
> suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
> VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
> mm.  Flush workers in suspend to guarantee that no worker sees the new
> mm and old VA in between.
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  drivers/vhost/vdpa.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 8fe1562d24af..9673e8e20d11 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
>  {
>         struct vdpa_device *vdpa = v->vdpa;
>         const struct vdpa_config_ops *ops = vdpa->config;
> +       struct vhost_dev *vdev = &v->vdev;
>
>         if (!ops->suspend)
>                 return -EOPNOTSUPP;
>
> +       if (vdev->use_worker)
> +               vhost_dev_flush(vdev);

It looks to me like it's better to check use_woker in vhost_dev_flush.

Thanks


> +
>         return ops->suspend(vdpa);
>  }
>
> --
> 2.39.3
>
Re: [RFC V1 07/13] vhost-vdpa: flush workers on suspend
Posted by Mike Christie 2 years ago 
On 1/10/24 9:09 PM, Jason Wang wrote:
> On Thu, Jan 11, 2024 at 4:40 AM Steve Sistare <steven.sistare@oracle.com> wrote:
>>
>> To pass ownership of a live vdpa device to a new process, the user
>> suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
>> VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
>> mm.  Flush workers in suspend to guarantee that no worker sees the new
>> mm and old VA in between.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> ---
>>  drivers/vhost/vdpa.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>> index 8fe1562d24af..9673e8e20d11 100644
>> --- a/drivers/vhost/vdpa.c
>> +++ b/drivers/vhost/vdpa.c
>> @@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
>>  {
>>         struct vdpa_device *vdpa = v->vdpa;
>>         const struct vdpa_config_ops *ops = vdpa->config;
>> +       struct vhost_dev *vdev = &v->vdev;
>>
>>         if (!ops->suspend)
>>                 return -EOPNOTSUPP;
>>
>> +       if (vdev->use_worker)
>> +               vhost_dev_flush(vdev);
> 
> It looks to me like it's better to check use_woker in vhost_dev_flush.
> 

You can now just call vhost_dev_flush and it will do the right thing.
The xa_for_each loop will only flush workers if they have been setup,
so for vdpa it will not find/flush anything.
Re: [RFC V1 07/13] vhost-vdpa: flush workers on suspend
Posted by Jason Wang 2 years ago 
On Fri, Jan 12, 2024 at 12:18 AM Mike Christie
<michael.christie@oracle.com> wrote:
>
> On 1/10/24 9:09 PM, Jason Wang wrote:
> > On Thu, Jan 11, 2024 at 4:40 AM Steve Sistare <steven.sistare@oracle.com> wrote:
> >>
> >> To pass ownership of a live vdpa device to a new process, the user
> >> suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
> >> VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
> >> mm.  Flush workers in suspend to guarantee that no worker sees the new
> >> mm and old VA in between.
> >>
> >> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> >> ---
> >>  drivers/vhost/vdpa.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> >> index 8fe1562d24af..9673e8e20d11 100644
> >> --- a/drivers/vhost/vdpa.c
> >> +++ b/drivers/vhost/vdpa.c
> >> @@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
> >>  {
> >>         struct vdpa_device *vdpa = v->vdpa;
> >>         const struct vdpa_config_ops *ops = vdpa->config;
> >> +       struct vhost_dev *vdev = &v->vdev;
> >>
> >>         if (!ops->suspend)
> >>                 return -EOPNOTSUPP;
> >>
> >> +       if (vdev->use_worker)
> >> +               vhost_dev_flush(vdev);
> >
> > It looks to me like it's better to check use_woker in vhost_dev_flush.
> >
>
> You can now just call vhost_dev_flush and it will do the right thing.
> The xa_for_each loop will only flush workers if they have been setup,
> so for vdpa it will not find/flush anything.

Right.

Thanks

>
>
>
Re: [RFC V1 07/13] vhost-vdpa: flush workers on suspend
Posted by Steven Sistare 2 years ago 
On 1/11/2024 9:28 PM, Jason Wang wrote:
> On Fri, Jan 12, 2024 at 12:18 AM Mike Christie
> <michael.christie@oracle.com> wrote:
>>
>> On 1/10/24 9:09 PM, Jason Wang wrote:
>>> On Thu, Jan 11, 2024 at 4:40 AM Steve Sistare <steven.sistare@oracle.com> wrote:
>>>>
>>>> To pass ownership of a live vdpa device to a new process, the user
>>>> suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
>>>> VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
>>>> mm.  Flush workers in suspend to guarantee that no worker sees the new
>>>> mm and old VA in between.
>>>>
>>>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>>>> ---
>>>>  drivers/vhost/vdpa.c | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>>>> index 8fe1562d24af..9673e8e20d11 100644
>>>> --- a/drivers/vhost/vdpa.c
>>>> +++ b/drivers/vhost/vdpa.c
>>>> @@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
>>>>  {
>>>>         struct vdpa_device *vdpa = v->vdpa;
>>>>         const struct vdpa_config_ops *ops = vdpa->config;
>>>> +       struct vhost_dev *vdev = &v->vdev;
>>>>
>>>>         if (!ops->suspend)
>>>>                 return -EOPNOTSUPP;
>>>>
>>>> +       if (vdev->use_worker)
>>>> +               vhost_dev_flush(vdev);
>>>
>>> It looks to me like it's better to check use_woker in vhost_dev_flush.
>>
>> You can now just call vhost_dev_flush and it will do the right thing.
>> The xa_for_each loop will only flush workers if they have been setup,
>> so for vdpa it will not find/flush anything.

Very good, I will drop this patch.

- Steve

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