Re: [PATCH v2 2/8] vhost-vdpa: use bind_mm/unbind_mm device callbacks

Stefano Garzarella
2023-03-16T08:32:41Z

On Tue, Mar 14, 2023 at 11:48:33AM +0800, Jason Wang wrote:
>On Thu, Mar 2, 2023 at 7:34 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>>
>> When the user call VHOST_SET_OWNER ioctl and the vDPA device
>> has `use_va` set to true, let's call the bind_mm callback.
>> In this way we can bind the device to the user address space
>> and directly use the user VA.
>>
>> The unbind_mm callback is called during the release after
>> stopping the device.
>>
>> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>> ---
>>
>> Notes:
>> v2:
>> - call the new unbind_mm callback during the release [Jason]
>> - avoid to call bind_mm callback after the reset, since the device
>> is not detaching it now during the reset
>>
>> drivers/vhost/vdpa.c | 30 ++++++++++++++++++++++++++++++
>> 1 file changed, 30 insertions(+)
>>
>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>> index dc12dbd5b43b..1ab89fccd825 100644
>> --- a/drivers/vhost/vdpa.c
>> +++ b/drivers/vhost/vdpa.c
>> @@ -219,6 +219,28 @@ static int vhost_vdpa_reset(struct vhost_vdpa *v)
>> return vdpa_reset(vdpa);
>> }
>>
>> +static long vhost_vdpa_bind_mm(struct vhost_vdpa *v)
>> +{
>> + struct vdpa_device *vdpa = v->vdpa;
>> + const struct vdpa_config_ops *ops = vdpa->config;
>> +
>> + if (!vdpa->use_va || !ops->bind_mm)
>> + return 0;
>> +
>> + return ops->bind_mm(vdpa, v->vdev.mm);
>> +}
>> +
>> +static void vhost_vdpa_unbind_mm(struct vhost_vdpa *v)
>> +{
>> + struct vdpa_device *vdpa = v->vdpa;
>> + const struct vdpa_config_ops *ops = vdpa->config;
>> +
>> + if (!vdpa->use_va || !ops->unbind_mm)
>> + return;
>> +
>> + ops->unbind_mm(vdpa);
>> +}
>> +
>> static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
>> {
>> struct vdpa_device *vdpa = v->vdpa;
>> @@ -711,6 +733,13 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
>> break;
>> default:
>> r = vhost_dev_ioctl(&v->vdev, cmd, argp);
>> + if (!r && cmd == VHOST_SET_OWNER) {
>> + r = vhost_vdpa_bind_mm(v);
>> + if (r) {
>> + vhost_dev_reset_owner(&v->vdev, NULL);
>> + break;
>> + }
>> + }
>
>Nit: is it better to have a new condition/switch branch instead of
>putting them under default? (as what vring_ioctl did).

Yep, I agree!

I'll change it.

Thanks,
Stefano