? 2021/4/8 ??11:59, Michael S. Tsirkin ??:> On Thu, Apr 08, 2021 at 04:26:48PM +0800, Jason Wang wrote:
>> This patch mandates 1.0 for vDPA devices. The goal is to have the
>> semantic of normative statement in the virtio spec and eliminate the
>> burden of transitional device for both vDPA bus and vDPA parent.
>>
>> uAPI seems fine since all the vDPA parent mandates
>> VIRTIO_F_ACCESS_PLATFORM which implies 1.0 devices.
>>
>> For legacy guests, it can still work since Qemu will mediate when
>> necessary (e.g doing the endian conversion).
>>
>> Signed-off-by: Jason Wang <jasowang at redhat.com>
> Hmm. If we do this, don't we still have a problem with
> legacy drivers which don't ack 1.0?
Yes, but it's not something that is introduced in this commit. The
legacy driver never work ...
> Note 1.0 affects ring endianness which is not mediated in QEMU
> so QEMU can't pretend to device guest is 1.0.
Right, I plan to send patches to do mediation in the Qemu to unbreak
legacy drivers.
Thanks
>
>
>
>
>
>> ---
>> include/linux/vdpa.h | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
>> index 0fefeb976877..cfde4ec999b4 100644
>> --- a/include/linux/vdpa.h
>> +++ b/include/linux/vdpa.h
>> @@ -6,6 +6,7 @@
>> #include <linux/device.h>
>> #include <linux/interrupt.h>
>> #include <linux/vhost_iotlb.h>
>> +#include <uapi/linux/virtio_config.h>
>>
>> /**
>> * vDPA callback definition.
>> @@ -317,6 +318,11 @@ static inline int vdpa_set_features(struct
vdpa_device *vdev, u64 features)
>> {
>> const struct vdpa_config_ops *ops = vdev->config;
>>
>> + /* Mandating 1.0 to have semantics of normative statements in
>> + * the spec. */
>> + if (!(features & BIT_ULL(VIRTIO_F_VERSION_1)))
>> + return -EINVAL;
>> +
>> vdev->features_valid = true;
>> return ops->set_features(vdev, features);
>> }
>> --
>> 2.25.1