Jason Wang
2023-Mar-03 03:32 UTC
[PATCH v4 01/15] vdpa net: move iova tree creation from init to start
? 2023/3/1 15:01, Eugenio Perez Martin ??:> On Mon, Feb 27, 2023 at 8:04 AM Jason Wang <jasowang at redhat.com> wrote: >> >> ? 2023/2/24 23:54, Eugenio P?rez ??: >>> 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 P?rez <eperezma at redhat.com> >>> Acked-by: Jason Wang <jasowang at 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() 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;