Messages in this thread | | | Subject | Re: [RFC PATCH] vdpa: mandate 1.0 device | From | Jason Wang <> | Date | Fri, 9 Apr 2021 12:47:55 +0800 |
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在 2021/4/8 下午11:59, Michael S. Tsirkin 写道: > 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@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
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