On Wed, Sep 15, 2021 at 3:31 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Wed, Sep 15, 2021 at 11:24:53AM +0800, Wu Zongyong wrote: > > On Tue, Sep 14, 2021 at 08:58:28AM -0400, Michael S. Tsirkin wrote: > > > On Tue, Sep 14, 2021 at 08:24:51PM +0800, Wu Zongyong wrote: > > > > This new attribute advertises whether the vdpa device is legacy or not. > > > > Users can pick right virtqueue size if the vdpa device is legacy which > > > > doesn't support to change virtqueue size. > > > > > > > > Signed-off-by: Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx> > > > > > > So if we are bothering with legacy, I think there are > > > several things to do when building the interface > > > - support transitional devices, that is allow userspace > > > to tell device it's in legacy mode > > > - support reporting/setting supporting endian-ness > > > > It's true if we try to implement a general drvier for legacy. > > But this series is dedicated to implement a driver only for ENI. Is it > > necessary to implement what you said here in this series? > > To a certain degree, yes. > > I am thinking about the UAPI here. The new attribute is part of that. > E.g. userspace consuming this needs to be more or less hardware agnostic > and not depend on specifics of ENI. > > Otherwise if userspace assumes legacy==eni then it will break with > other hardware. > > One way to test how generic it all is would be adding legacy support in > the simulator. I don't get why we need to support legacy devices e.g it doesn't have ACCESS_PLATFORM support. I think we should re-consider to mandate 1.0 devices. https://lore.kernel.org/lkml/20210408082648.20145-1-jasowang@xxxxxxxxxx/ And it will complicate all of the different layers. Thanks > > > > > > > > --- > > > > drivers/vdpa/vdpa.c | 6 ++++++ > > > > drivers/virtio/virtio_vdpa.c | 7 ++++++- > > > > include/uapi/linux/vdpa.h | 1 + > > > > 3 files changed, 13 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c > > > > index 1dc121a07a93..533d7f589eee 100644 > > > > --- a/drivers/vdpa/vdpa.c > > > > +++ b/drivers/vdpa/vdpa.c > > > > @@ -12,6 +12,7 @@ > > > > #include <linux/slab.h> > > > > #include <linux/vdpa.h> > > > > #include <uapi/linux/vdpa.h> > > > > +#include <uapi/linux/virtio_config.h> > > > > #include <net/genetlink.h> > > > > #include <linux/mod_devicetable.h> > > > > > > > > @@ -494,6 +495,7 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > u16 max_vq_size; > > > > u32 device_id; > > > > u32 vendor_id; > > > > + u64 features; > > > > void *hdr; > > > > int err; > > > > > > > > @@ -508,6 +510,7 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > device_id = vdev->config->get_device_id(vdev); > > > > vendor_id = vdev->config->get_vendor_id(vdev); > > > > max_vq_size = vdev->config->get_vq_num_max(vdev); > > > > + features = vdev->config->get_features(vdev); > > > > > > > > err = -EMSGSIZE; > > > > if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev->dev))) > > > > @@ -520,6 +523,9 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq > > > > goto msg_err; > > > > if (nla_put_u16(msg, VDPA_ATTR_DEV_MAX_VQ_SIZE, max_vq_size)) > > > > goto msg_err; > > > > + if (features & BIT_ULL(VIRTIO_F_VERSION_1) && > > > > + nla_put_flag(msg, VDPA_ATTR_DEV_VERSION_1)) > > > > + goto msg_err; > > > > > > > > genlmsg_end(msg, hdr); > > > > return 0; > > > > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c > > > > index 72eaef2caeb1..1cba957c4cdc 100644 > > > > --- a/drivers/virtio/virtio_vdpa.c > > > > +++ b/drivers/virtio/virtio_vdpa.c > > > > @@ -7,6 +7,7 @@ > > > > * > > > > */ > > > > > > > > +#include "linux/virtio_config.h" > > > > #include <linux/init.h> > > > > #include <linux/module.h> > > > > #include <linux/device.h> > > > > @@ -145,6 +146,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > > /* Assume split virtqueue, switch to packed if necessary */ > > > > struct vdpa_vq_state state = {0}; > > > > unsigned long flags; > > > > + bool may_reduce_num = false; > > > > u32 align, num; > > > > int err; > > > > > > > > @@ -169,10 +171,13 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > > goto error_new_virtqueue; > > > > } > > > > > > > > + if (ops->get_features(vdpa) & BIT_ULL(VIRTIO_F_VERSION_1)) > > > > + may_reduce_num = true; > > > > + > > > > /* Create the vring */ > > > > align = ops->get_vq_align(vdpa); > > > > vq = vring_create_virtqueue(index, num, align, vdev, > > > > - true, true, ctx, > > > > + true, may_reduce_num, ctx, > > > > virtio_vdpa_notify, callback, name); > > > > if (!vq) { > > > > err = -ENOMEM; > > > > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h > > > > index 66a41e4ec163..ce0b74276a5b 100644 > > > > --- a/include/uapi/linux/vdpa.h > > > > +++ b/include/uapi/linux/vdpa.h > > > > @@ -32,6 +32,7 @@ enum vdpa_attr { > > > > VDPA_ATTR_DEV_VENDOR_ID, /* u32 */ > > > > VDPA_ATTR_DEV_MAX_VQS, /* u32 */ > > > > VDPA_ATTR_DEV_MAX_VQ_SIZE, /* u16 */ > > > > + VDPA_ATTR_DEV_VERSION_1, /* flag */ > > > > > > > > /* new attributes must be added above here */ > > > > VDPA_ATTR_MAX, > > > > -- > > > > 2.31.1 > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
