On Thu, Dec 7, 2023 at 7:50 PM Si-Wei Liu <si-wei....@oracle.com> wrote:
>
> The descriptor group for SVQ ASID allows the guest memory mapping
> to retain across SVQ switching, same as how isolated CVQ can do
> with a different ASID than the guest GPA space. Introduce an
> evaluation function to judge whether to flush or keep iotlb maps
> based on virtqueue's descriptor group and cvq isolation capability.
>
> Have to hook the evaluation function to NetClient's .poll op as
> .vhost_reset_status runs ahead of .stop, and .vhost_dev_start
> don't have access to the vhost-vdpa net's information.
>
> Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>
> ---
> net/vhost-vdpa.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 04718b2..e9b96ed 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -504,12 +504,36 @@ static int vhost_vdpa_net_load_cleanup(NetClientState
> *nc, NICState *nic)
> n->parent_obj.status &
> VIRTIO_CONFIG_S_DRIVER_OK);
> }
>
> +static void vhost_vdpa_net_data_eval_flush(NetClientState *nc, bool stop)
> +{
> + VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> + struct vhost_vdpa *v = &s->vhost_vdpa;
> +
> + if (!stop) {
> + return;
> + }
> +
> + if (s->vhost_vdpa.index == 0) {
> + if (s->always_svq) {
> + v->shared->flush_map = true;
Why do we need to reset the map in the case of always_svq?
> + } else if (!v->shared->svq_switching || v->desc_group >= 0) {
> + v->shared->flush_map = false;
> + } else {
> + v->shared->flush_map = true;
> + }
> + } else if (!s->always_svq && v->shared->svq_switching &&
> + v->desc_group < 0) {
> + v->shared->flush_map = true;
> + }
> +}
> +
I'm wondering, since we have the reference count for the memory
listener already, why not adding one refcnt if _start detect it can
keep the memory maps?
> static NetClientInfo net_vhost_vdpa_info = {
> .type = NET_CLIENT_DRIVER_VHOST_VDPA,
> .size = sizeof(VhostVDPAState),
> .receive = vhost_vdpa_receive,
> .start = vhost_vdpa_net_data_start,
> .load = vhost_vdpa_net_data_load,
> + .poll = vhost_vdpa_net_data_eval_flush,
> .stop = vhost_vdpa_net_client_stop,
> .cleanup = vhost_vdpa_cleanup,
> .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> @@ -1368,12 +1392,28 @@ static int vhost_vdpa_net_cvq_load(NetClientState *nc)
> return 0;
> }
>
> +static void vhost_vdpa_net_cvq_eval_flush(NetClientState *nc, bool stop)
> +{
> + VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> + struct vhost_vdpa *v = &s->vhost_vdpa;
> +
> + if (!stop) {
> + return;
> + }
> +
> + if (!v->shared->flush_map && !v->shared->svq_switching &&
> + !s->cvq_isolated && v->desc_group < 0) {
> + v->shared->flush_map = true;
> + }
> +}
> +
> static NetClientInfo net_vhost_vdpa_cvq_info = {
> .type = NET_CLIENT_DRIVER_VHOST_VDPA,
> .size = sizeof(VhostVDPAState),
> .receive = vhost_vdpa_receive,
> .start = vhost_vdpa_net_cvq_start,
> .load = vhost_vdpa_net_cvq_load,
> + .poll = vhost_vdpa_net_cvq_eval_flush,
> .stop = vhost_vdpa_net_cvq_stop,
> .cleanup = vhost_vdpa_cleanup,
> .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> --
> 1.8.3.1
>
