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Re: [PATCH v4 01/15] vdpa net: move iova tree creation from init to star
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From: |
Eugenio Perez Martin |
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Subject: |
Re: [PATCH v4 01/15] vdpa net: move iova tree creation from init to start |
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Date: |
Fri, 3 Mar 2023 09:00:53 +0100 |
On Fri, Mar 3, 2023 at 4:32 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2023/3/1 15:01, Eugenio Perez Martin 写道:
> > On Mon, Feb 27, 2023 at 8:04 AM Jason Wang <jasowang@redhat.com> wrote:
> >>
> >> 在 2023/2/24 23:54, Eugenio Pérez 写道:
> >>> Only create iova_tree if and when it is needed.
> >>>
> >>> The cleanup keeps being responsible of last VQ but this change allows it
> >>> to merge both cleanup functions.
> >>>
> >>> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> >>> Acked-by: Jason Wang <jasowang@redhat.com>
> >>> ---
> >>> v4:
> >>> * Remove leak of iova_tree because double allocation
> >>> * Document better the sharing of IOVA tree between data and CVQ
> >>> ---
> >>> net/vhost-vdpa.c | 113 ++++++++++++++++++++++++++++++++++-------------
> >>> 1 file changed, 83 insertions(+), 30 deletions(-)
> >>>
> >>> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> >>> index de5ed8ff22..b89c99066a 100644
> >>> --- a/net/vhost-vdpa.c
> >>> +++ b/net/vhost-vdpa.c
> >>> @@ -178,13 +178,9 @@ err_init:
> >>> static void vhost_vdpa_cleanup(NetClientState *nc)
> >>> {
> >>> VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> >>> - struct vhost_dev *dev = &s->vhost_net->dev;
> >>>
> >>> qemu_vfree(s->cvq_cmd_out_buffer);
> >>> qemu_vfree(s->status);
> >>> - if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> >>> - g_clear_pointer(&s->vhost_vdpa.iova_tree,
> >>> vhost_iova_tree_delete);
> >>> - }
> >>> if (s->vhost_net) {
> >>> vhost_net_cleanup(s->vhost_net);
> >>> g_free(s->vhost_net);
> >>> @@ -234,10 +230,64 @@ static ssize_t vhost_vdpa_receive(NetClientState
> >>> *nc, const uint8_t *buf,
> >>> return size;
> >>> }
> >>>
> >>> +/** From any vdpa net client, get the netclient of first queue pair */
> >>> +static VhostVDPAState *vhost_vdpa_net_first_nc_vdpa(VhostVDPAState *s)
> >>> +{
> >>> + NICState *nic = qemu_get_nic(s->nc.peer);
> >>> + NetClientState *nc0 = qemu_get_peer(nic->ncs, 0);
> >>> +
> >>> + return DO_UPCAST(VhostVDPAState, nc, nc0);
> >>> +}
> >>> +
> >>> +static void vhost_vdpa_net_data_start_first(VhostVDPAState *s)
> >>> +{
> >>> + struct vhost_vdpa *v = &s->vhost_vdpa;
> >>> +
> >>> + if (v->shadow_vqs_enabled) {
> >>> + v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> >>> + v->iova_range.last);
> >>> + }
> >>> +}
> >>> +
> >>> +static int vhost_vdpa_net_data_start(NetClientState *nc)
> >>> +{
> >>> + VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> >>> + struct vhost_vdpa *v = &s->vhost_vdpa;
> >>> +
> >>> + assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> >>> +
> >>> + if (v->index == 0) {
> >>> + vhost_vdpa_net_data_start_first(s);
> >>> + return 0;
> >>> + }
> >>> +
> >>> + if (v->shadow_vqs_enabled) {
> >>> + VhostVDPAState *s0 = vhost_vdpa_net_first_nc_vdpa(s);
> >>> + v->iova_tree = s0->vhost_vdpa.iova_tree;
> >>> + }
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void vhost_vdpa_net_client_stop(NetClientState *nc)
> >>> +{
> >>> + VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> >>> + struct vhost_dev *dev;
> >>> +
> >>> + assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> >>> +
> >>> + dev = s->vhost_vdpa.dev;
> >>> + if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> >>> + g_clear_pointer(&s->vhost_vdpa.iova_tree,
> >>> vhost_iova_tree_delete);
> >>> + }
> >>> +}
> >>> +
> >>> 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,
> >>> + .stop = vhost_vdpa_net_client_stop,
> >>
> >> Looking at the implementation, it seems nothing net specific, any reason
> >> we can't simply use vhost_vdpa_dev_start()?
> >>
> > IOVA tree must be shared between (at least) all dataplane vhost_vdpa.
> > How could we move the call to vhost_vdpa_net_first_nc_vdpa to
> > vhost_vdpa_dev_start?
>
>
> Ok, I think I get it. We should really consider to implement a parent
> structure in the future for vhost_vdpa then we can avoid tricks like:
>
> vq_index_end and vhost_vdpa_net_first_nc_vdpa()
>
Sounds right. Maybe it is enough to link all of them with a QLIST?
Thanks!
> Thanks
>
>
> >
> > A possibility is to always allocate it just in case. But it seems to
> > me it is better to not start allocating resources just in case :).
> >
> >>> .cleanup = vhost_vdpa_cleanup,
> >>> .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> >>> .has_ufo = vhost_vdpa_has_ufo,
> >>> @@ -351,7 +401,7 @@ dma_map_err:
> >>>
> >>> static int vhost_vdpa_net_cvq_start(NetClientState *nc)
> >>> {
> >>> - VhostVDPAState *s;
> >>> + VhostVDPAState *s, *s0;
> >>> struct vhost_vdpa *v;
> >>> uint64_t backend_features;
> >>> int64_t cvq_group;
> >>> @@ -415,8 +465,6 @@ static int vhost_vdpa_net_cvq_start(NetClientState
> >>> *nc)
> >>> return r;
> >>> }
> >>>
> >>> - v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> >>> - v->iova_range.last);
> >>> v->shadow_vqs_enabled = true;
> >>> s->vhost_vdpa.address_space_id = VHOST_VDPA_NET_CVQ_ASID;
> >>>
> >>> @@ -425,6 +473,27 @@ out:
> >>> return 0;
> >>> }
> >>>
> >>> + s0 = vhost_vdpa_net_first_nc_vdpa(s);
> >>> + if (s0->vhost_vdpa.iova_tree) {
> >>> + /*
> >>> + * SVQ is already configured for all virtqueues. Reuse IOVA
> >>> tree for
> >>> + * simplicity, wether CVQ shares ASID with guest or not, because:
> >>
> >> Typo, should be "whether", or "regardless of whether"(not a native
> >> speaker).
> >>
> > Good catch, I can fix it in the next version.
> >
> > Thanks!
> >
> >> Other looks good.
> >>
> >> Thanks
> >>
> >>
> >>> + * - Memory listener need access to guest's memory addresses
> >>> allocated
> >>> + * in the IOVA tree.
> >>> + * - There should be plenty of IOVA address space for both ASID
> >>> not to
> >>> + * worry about collisions between them. Guest's translations
> >>> are
> >>> + * still validated with virtio virtqueue_pop so there is no
> >>> risk for
> >>> + * the guest to access memory it shouldn't.
> >>> + *
> >>> + * To allocate a iova tree per ASID is doable but it complicates
> >>> the
> >>> + * code and it is not worth for the moment.
> >>> + */
> >>> + v->iova_tree = s0->vhost_vdpa.iova_tree;
> >>> + } else {
> >>> + v->iova_tree = vhost_iova_tree_new(v->iova_range.first,
> >>> + v->iova_range.last);
> >>> + }
> >>> +
> >>> r = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer,
> >>> vhost_vdpa_net_cvq_cmd_page_len(),
> >>> false);
> >>> if (unlikely(r < 0)) {
> >>> @@ -449,15 +518,9 @@ static void vhost_vdpa_net_cvq_stop(NetClientState
> >>> *nc)
> >>> if (s->vhost_vdpa.shadow_vqs_enabled) {
> >>> vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa,
> >>> s->cvq_cmd_out_buffer);
> >>> vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->status);
> >>> - if (!s->always_svq) {
> >>> - /*
> >>> - * If only the CVQ is shadowed we can delete this safely.
> >>> - * If all the VQs are shadows this will be needed by the
> >>> time the
> >>> - * device is started again to register SVQ vrings and
> >>> similar.
> >>> - */
> >>> - g_clear_pointer(&s->vhost_vdpa.iova_tree,
> >>> vhost_iova_tree_delete);
> >>> - }
> >>> }
> >>> +
> >>> + vhost_vdpa_net_client_stop(nc);
> >>> }
> >>>
> >>> static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState *s, size_t
> >>> out_len,
> >>> @@ -667,8 +730,7 @@ static NetClientState
> >>> *net_vhost_vdpa_init(NetClientState *peer,
> >>> int nvqs,
> >>> bool is_datapath,
> >>> bool svq,
> >>> - struct vhost_vdpa_iova_range
> >>> iova_range,
> >>> - VhostIOVATree *iova_tree)
> >>> + struct vhost_vdpa_iova_range
> >>> iova_range)
> >>> {
> >>> NetClientState *nc = NULL;
> >>> VhostVDPAState *s;
> >>> @@ -690,7 +752,6 @@ static NetClientState
> >>> *net_vhost_vdpa_init(NetClientState *peer,
> >>> s->vhost_vdpa.shadow_vqs_enabled = svq;
> >>> s->vhost_vdpa.iova_range = iova_range;
> >>> s->vhost_vdpa.shadow_data = svq;
> >>> - s->vhost_vdpa.iova_tree = iova_tree;
> >>> if (!is_datapath) {
> >>> s->cvq_cmd_out_buffer =
> >>> qemu_memalign(qemu_real_host_page_size(),
> >>>
> >>> vhost_vdpa_net_cvq_cmd_page_len());
> >>> @@ -760,7 +821,6 @@ int net_init_vhost_vdpa(const Netdev *netdev, const
> >>> char *name,
> >>> uint64_t features;
> >>> int vdpa_device_fd;
> >>> g_autofree NetClientState **ncs = NULL;
> >>> - g_autoptr(VhostIOVATree) iova_tree = NULL;
> >>> struct vhost_vdpa_iova_range iova_range;
> >>> NetClientState *nc;
> >>> int queue_pairs, r, i = 0, has_cvq = 0;
> >>> @@ -812,12 +872,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const
> >>> char *name,
> >>> goto err;
> >>> }
> >>>
> >>> - if (opts->x_svq) {
> >>> - if (!vhost_vdpa_net_valid_svq_features(features, errp)) {
> >>> - goto err_svq;
> >>> - }
> >>> -
> >>> - iova_tree = vhost_iova_tree_new(iova_range.first,
> >>> iova_range.last);
> >>> + if (opts->x_svq && !vhost_vdpa_net_valid_svq_features(features,
> >>> errp)) {
> >>> + goto err;
> >>> }
> >>>
> >>> ncs = g_malloc0(sizeof(*ncs) * queue_pairs);
> >>> @@ -825,7 +881,7 @@ 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_range, iova_tree);
> >>> + iova_range);
> >>> if (!ncs[i])
> >>> goto err;
> >>> }
> >>> @@ -833,13 +889,11 @@ int net_init_vhost_vdpa(const Netdev *netdev, const
> >>> char *name,
> >>> if (has_cvq) {
> >>> nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
> >>> vdpa_device_fd, i, 1, false,
> >>> - opts->x_svq, iova_range, iova_tree);
> >>> + opts->x_svq, iova_range);
> >>> if (!nc)
> >>> goto err;
> >>> }
> >>>
> >>> - /* iova_tree ownership belongs to last NetClientState */
> >>> - g_steal_pointer(&iova_tree);
> >>> return 0;
> >>>
> >>> err:
> >>> @@ -849,7 +903,6 @@ err:
> >>> }
> >>> }
> >>>
> >>> -err_svq:
> >>> qemu_close(vdpa_device_fd);
> >>>
> >>> return -1;
>