Re: [PATCH v2 7/7] vdpa: Always start CVQ in SVQ mode

[Jason Wang]

在 2022/7/22 21:43, Eugenio Pérez 写道:
> Isolate control virtqueue in its own group, allowing to intercept control
> commands but letting dataplane run totally passthrough to the guest.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   hw/virtio/vhost-vdpa.c |   3 +-
>   net/vhost-vdpa.c       | 158 +++++++++++++++++++++++++++++++++++++++--
>   2 files changed, 156 insertions(+), 5 deletions(-)
>
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 79623badf2..fe1c85b086 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -668,7 +668,8 @@ static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
>   {
>       uint64_t features;
>       uint64_t f = 0x1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2 |
> -        0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH;
> +        0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH |
> +        0x1ULL << VHOST_BACKEND_F_IOTLB_ASID;
>       int r;
>   
>       if (vhost_vdpa_call(dev, VHOST_GET_BACKEND_FEATURES, &features)) {
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 6c1c64f9b1..f5075ef487 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -37,6 +37,9 @@ typedef struct VhostVDPAState {
>       /* Control commands shadow buffers */
>       void *cvq_cmd_out_buffer, *cvq_cmd_in_buffer;
>   
> +    /* Number of address spaces supported by the device */
> +    unsigned address_space_num;
> +
>       /* The device always have SVQ enabled */
>       bool always_svq;
>       bool started;
> @@ -100,6 +103,8 @@ static const uint64_t vdpa_svq_device_features =
>       BIT_ULL(VIRTIO_NET_F_RSC_EXT) |
>       BIT_ULL(VIRTIO_NET_F_STANDBY);
>   
> +#define VHOST_VDPA_NET_CVQ_ASID 1
> +
>   VHostNetState *vhost_vdpa_get_vhost_net(NetClientState *nc)
>   {
>       VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> @@ -214,6 +219,109 @@ static ssize_t vhost_vdpa_receive(NetClientState *nc, 
> const uint8_t *buf,
>       return 0;
>   }
>   
> +static int vhost_vdpa_get_vring_group(int device_fd,
> +                                      struct vhost_vring_state *state)
> +{
> +    int r = ioctl(device_fd, VHOST_VDPA_GET_VRING_GROUP, state);
> +    return r < 0 ? -errno : 0;
> +}


It would be more convenient for the caller if we can simply return 0 here.


> +
> +/**
> + * Check if all the virtqueues of the virtio device are in a different vq than
> + * the last vq. VQ group of last group passed in cvq_group.
> + */
> +static bool vhost_vdpa_cvq_group_is_independent(struct vhost_vdpa *v,
> +                                            struct vhost_vring_state cvq_group)
> +{
> +    struct vhost_dev *dev = v->dev;
> +    int ret;
> +
> +    for (int i = 0; i < (dev->vq_index_end - 1); ++i) {
> +        struct vhost_vring_state vq_group = {
> +            .index = i,
> +        };
> +
> +        ret = vhost_vdpa_get_vring_group(v->device_fd, &vq_group);
> +        if (unlikely(ret)) {
> +            goto call_err;
> +        }
> +        if (unlikely(vq_group.num == cvq_group.num)) {
> +            error_report("CVQ %u group is the same as VQ %u one (%u)",
> +                         cvq_group.index, vq_group.index, cvq_group.num);


Any reason we need error_report() here?

Btw, I'd suggest to introduce new field in vhost_vdpa, then we can get 
and store the group_id there during init.

This could be useful for the future e.g PASID virtualization.


> +            return false;
> +        }
> +    }
> +
> +    return true;
> +
> +call_err:
> +    error_report("Can't read vq group, errno=%d (%s)", -ret, g_strerror(-ret));
> +    return false;
> +}
> +
> +static int vhost_vdpa_set_address_space_id(struct vhost_vdpa *v,
> +                                           unsigned vq_group,
> +                                           unsigned asid_num)
> +{
> +    struct vhost_vring_state asid = {
> +        .index = vq_group,
> +        .num = asid_num,
> +    };
> +    int ret;
> +
> +    ret = ioctl(v->device_fd, VHOST_VDPA_SET_GROUP_ASID, &asid);
> +    if (unlikely(ret < 0)) {
> +        error_report("Can't set vq group %u asid %u, errno=%d (%s)",
> +            asid.index, asid.num, errno, g_strerror(errno));
> +    }
> +    return ret;
> +}
> +
> +static void vhost_vdpa_net_prepare(NetClientState *nc)
> +{
> +    VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> +    struct vhost_vdpa *v = &s->vhost_vdpa;
> +    struct vhost_dev *dev = v->dev;
> +    struct vhost_vring_state cvq_group = {
> +        .index = v->dev->vq_index_end - 1,
> +    };
> +    int r;
> +
> +    assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> +
> +    if (dev->nvqs != 1 || dev->vq_index + dev->nvqs != dev->vq_index_end) {
> +        /* Only interested in CVQ */
> +        return;
> +    }
> +
> +    if (s->always_svq) {
> +        /* SVQ is already enabled */
> +        return;
> +    }
> +
> +    if (s->address_space_num < 2) {
> +        v->shadow_vqs_enabled = false;
> +        return;
> +    }
> +
> +    r = vhost_vdpa_get_vring_group(v->device_fd, &cvq_group);
> +    if (unlikely(r)) {
> +        error_report("Can't read cvq group, errno=%d (%s)", r, g_strerror(-r));
> +        v->shadow_vqs_enabled = false;
> +        return;
> +    }
> +
> +    if (!vhost_vdpa_cvq_group_is_independent(v, cvq_group)) {
> +        v->shadow_vqs_enabled = false;
> +        return;
> +    }
> +
> +    r = vhost_vdpa_set_address_space_id(v, cvq_group.num,
> +                                        VHOST_VDPA_NET_CVQ_ASID);
> +    v->shadow_vqs_enabled = r == 0;
> +    s->vhost_vdpa.address_space_id = r == 0 ? 1 : 0;


I'd expect this to be done net_init_vhost_vdpa(). Or any advantage of 
initializing thing here?


> +}
> +
>   static void vhost_vdpa_cvq_unmap_buf(struct vhost_vdpa *v, void *addr)
>   {
>       VhostIOVATree *tree = v->iova_tree;
> @@ -432,6 +540,7 @@ static NetClientInfo net_vhost_vdpa_info = {
>           .type = NET_CLIENT_DRIVER_VHOST_VDPA,
>           .size = sizeof(VhostVDPAState),
>           .receive = vhost_vdpa_receive,
> +        .prepare = vhost_vdpa_net_prepare,
>           .start = vhost_vdpa_net_start,
>           .cleanup = vhost_vdpa_cleanup,
>           .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> @@ -542,12 +651,40 @@ static const VhostShadowVirtqueueOps 
> vhost_vdpa_net_svq_ops = {
>       .avail_handler = vhost_vdpa_net_handle_ctrl_avail,
>   };
>   
> +static bool vhost_vdpa_get_as_num(int vdpa_device_fd, unsigned *num_as,
> +                                  Error **errp)


Let's simply return int as the #as here.

Thanks


> +{
> +    uint64_t features;
> +    int r;
> +
> +    r = ioctl(vdpa_device_fd, VHOST_GET_BACKEND_FEATURES, &features);
> +    if (unlikely(r < 0)) {
> +        error_setg_errno(errp, errno, "Cannot get backend features");
> +        return r;
> +    }
> +
> +    if (!(features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID))) {
> +        *num_as = 1;
> +        return 0;
> +    }
> +
> +    r = ioctl(vdpa_device_fd, VHOST_VDPA_GET_AS_NUM, num_as);
> +    if (unlikely(r < 0)) {
> +        error_setg_errno(errp, errno,
> +                         "Cannot retrieve number of supported ASs");
> +        return r;
> +    }
> +
> +    return 0;
> +}
> +
>   static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
>                                              const char *device,
>                                              const char *name,
>                                              int vdpa_device_fd,
>                                              int queue_pair_index,
>                                              int nvqs,
> +                                           unsigned nas,
>                                              bool is_datapath,
>                                              bool svq,
>                                              VhostIOVATree *iova_tree)
> @@ -566,6 +703,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
> *peer,
>       snprintf(nc->info_str, sizeof(nc->info_str), TYPE_VHOST_VDPA);
>       s = DO_UPCAST(VhostVDPAState, nc, nc);
>   
> +    s->address_space_num = nas;
>       s->vhost_vdpa.device_fd = vdpa_device_fd;
>       s->vhost_vdpa.index = queue_pair_index;
>       s->always_svq = svq;
> @@ -651,6 +789,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>       g_autoptr(VhostIOVATree) iova_tree = NULL;
>       NetClientState *nc;
>       int queue_pairs, r, i, has_cvq = 0;
> +    unsigned num_as = 1;
> +    bool svq_cvq;
>   
>       assert(netdev->type == NET_CLIENT_DRIVER_VHOST_VDPA);
>       opts = &netdev->u.vhost_vdpa;
> @@ -676,7 +816,17 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>           return queue_pairs;
>       }
>   
> -    if (opts->x_svq) {
> +    svq_cvq = opts->x_svq;
> +    if (has_cvq && !opts->x_svq) {
> +        r = vhost_vdpa_get_as_num(vdpa_device_fd, &num_as, errp);
> +        if (unlikely(r < 0)) {
> +            return r;
> +        }
> +
> +        svq_cvq = num_as > 1;
> +    }
> +
> +    if (opts->x_svq || svq_cvq) {
>           struct vhost_vdpa_iova_range iova_range;
>   
>           uint64_t invalid_dev_features =
> @@ -699,15 +849,15 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char 
> *name,
>   
>       for (i = 0; i < queue_pairs; i++) {
>           ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
> -                                     vdpa_device_fd, i, 2, true, opts->x_svq,
> -                                     iova_tree);
> +                                     vdpa_device_fd, i, 2, num_as, true,
> +                                     opts->x_svq, iova_tree);
>           if (!ncs[i])
>               goto err;
>       }
>   
>       if (has_cvq) {
>           nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
> -                                 vdpa_device_fd, i, 1, false,
> +                                 vdpa_device_fd, i, 1, num_as, false,
>                                    opts->x_svq, iova_tree);
>           if (!nc)
>               goto err;