|
| From: | Jason Wang |
| Subject: | Re: [PATCH v4 01/15] vdpa net: move iova tree creation from init to start |
| Date: | Fri, 3 Mar 2023 11:32:27 +0800 |
| User-agent: | Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 |
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() 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;
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