From 503e355465ba0eafad49c2e174995d2e234ed288 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Mon, 21 Mar 2022 15:30:37 +0000 Subject: [PATCH] virtio/vhost-user: dynamically assign VhostUserHostNotifiers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit At a couple of hundred bytes per notifier allocating one for every potential queue is very wasteful as most devices only have a few queues. Instead of having this handled statically dynamically assign them and track in a GPtrArray. [AJB: it's hard to trigger the vhost notifiers code, I assume as it requires a KVM guest with appropriate backend] Signed-off-by: Alex Bennée Message-Id: <20220321153037.3622127-14-alex.bennee@linaro.org> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/trace-events | 1 + hw/virtio/vhost-user.c | 83 +++++++++++++++++++++++++++------- include/hw/virtio/vhost-user.h | 42 ++++++++++++++++- 3 files changed, 108 insertions(+), 18 deletions(-) diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events index 65e3b704ec..ab8e095b73 100644 --- a/hw/virtio/trace-events +++ b/hw/virtio/trace-events @@ -23,6 +23,7 @@ vhost_user_postcopy_waker_found(uint64_t client_addr) "0x%"PRIx64 vhost_user_postcopy_waker_nomatch(const char *rb, uint64_t rb_offset) "%s + 0x%"PRIx64 vhost_user_read(uint32_t req, uint32_t flags) "req:%d flags:0x%"PRIx32"" vhost_user_write(uint32_t req, uint32_t flags) "req:%d flags:0x%"PRIx32"" +vhost_user_create_notifier(int idx, void *n) "idx:%d n:%p" # vhost-vdpa.c vhost_vdpa_dma_map(void *vdpa, int fd, uint32_t msg_type, uint64_t iova, uint64_t size, uint64_t uaddr, uint8_t perm, uint8_t type) "vdpa:%p fd: %d msg_type: %"PRIu32" iova: 0x%"PRIx64" size: 0x%"PRIx64" uaddr: 0x%"PRIx64" perm: 0x%"PRIx8" type: %"PRIu8 diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index b0d417651d..b040c1ad2b 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1174,14 +1174,16 @@ static void vhost_user_host_notifier_free(VhostUserHostNotifier *n) n->unmap_addr = NULL; } -static void vhost_user_host_notifier_remove(VhostUserState *user, - VirtIODevice *vdev, int queue_idx) +/* + * clean-up function for notifier, will finally free the structure + * under rcu. + */ +static void vhost_user_host_notifier_remove(VhostUserHostNotifier *n, + VirtIODevice *vdev) { - VhostUserHostNotifier *n = &user->notifier[queue_idx]; - if (n->addr) { if (vdev) { - virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false); + virtio_queue_set_host_notifier_mr(vdev, n->idx, &n->mr, false); } assert(!n->unmap_addr); n->unmap_addr = n->addr; @@ -1225,6 +1227,15 @@ static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable) return 0; } +static VhostUserHostNotifier *fetch_notifier(VhostUserState *u, + int idx) +{ + if (idx >= u->notifiers->len) { + return NULL; + } + return g_ptr_array_index(u->notifiers, idx); +} + static int vhost_user_get_vring_base(struct vhost_dev *dev, struct vhost_vring_state *ring) { @@ -1237,7 +1248,10 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev, }; struct vhost_user *u = dev->opaque; - vhost_user_host_notifier_remove(u->user, dev->vdev, ring->index); + VhostUserHostNotifier *n = fetch_notifier(u->user, ring->index); + if (n) { + vhost_user_host_notifier_remove(n, dev->vdev); + } ret = vhost_user_write(dev, &msg, NULL, 0); if (ret < 0) { @@ -1502,6 +1516,29 @@ static int vhost_user_slave_handle_config_change(struct vhost_dev *dev) return dev->config_ops->vhost_dev_config_notifier(dev); } +/* + * Fetch or create the notifier for a given idx. Newly created + * notifiers are added to the pointer array that tracks them. + */ +static VhostUserHostNotifier *fetch_or_create_notifier(VhostUserState *u, + int idx) +{ + VhostUserHostNotifier *n = NULL; + if (idx >= u->notifiers->len) { + g_ptr_array_set_size(u->notifiers, idx); + } + + n = g_ptr_array_index(u->notifiers, idx); + if (!n) { + n = g_new0(VhostUserHostNotifier, 1); + n->idx = idx; + g_ptr_array_insert(u->notifiers, idx, n); + trace_vhost_user_create_notifier(idx, n); + } + + return n; +} + static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev, VhostUserVringArea *area, int fd) @@ -1521,9 +1558,12 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev, return -EINVAL; } - n = &user->notifier[queue_idx]; - - vhost_user_host_notifier_remove(user, vdev, queue_idx); + /* + * Fetch notifier and invalidate any old data before setting up + * new mapped address. + */ + n = fetch_or_create_notifier(user, queue_idx); + vhost_user_host_notifier_remove(n, vdev); if (area->u64 & VHOST_USER_VRING_NOFD_MASK) { return 0; @@ -2526,6 +2566,20 @@ static int vhost_user_set_inflight_fd(struct vhost_dev *dev, return vhost_user_write(dev, &msg, &inflight->fd, 1); } +static void vhost_user_state_destroy(gpointer data) +{ + VhostUserHostNotifier *n = (VhostUserHostNotifier *) data; + if (n) { + vhost_user_host_notifier_remove(n, NULL); + object_unparent(OBJECT(&n->mr)); + /* + * We can't free until vhost_user_host_notifier_remove has + * done it's thing so schedule the free with RCU. + */ + g_free_rcu(n, rcu); + } +} + bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp) { if (user->chr) { @@ -2534,23 +2588,18 @@ bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp) } user->chr = chr; user->memory_slots = 0; + user->notifiers = g_ptr_array_new_full(VIRTIO_QUEUE_MAX / 4, + &vhost_user_state_destroy); return true; } void vhost_user_cleanup(VhostUserState *user) { - int i; - VhostUserHostNotifier *n; - if (!user->chr) { return; } memory_region_transaction_begin(); - for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { - n = &user->notifier[i]; - vhost_user_host_notifier_remove(user, NULL, i); - object_unparent(OBJECT(&n->mr)); - } + user->notifiers = (GPtrArray *) g_ptr_array_free(user->notifiers, true); memory_region_transaction_commit(); user->chr = NULL; } diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h index 6e0e8a71a3..c6e693cd3f 100644 --- a/include/hw/virtio/vhost-user.h +++ b/include/hw/virtio/vhost-user.h @@ -11,21 +11,61 @@ #include "chardev/char-fe.h" #include "hw/virtio/virtio.h" +/** + * VhostUserHostNotifier - notifier information for one queue + * @rcu: rcu_head for cleanup + * @mr: memory region of notifier + * @addr: current mapped address + * @unmap_addr: address to be un-mapped + * @idx: virtioqueue index + * + * The VhostUserHostNotifier entries are re-used. When an old mapping + * is to be released it is moved to @unmap_addr and @addr is replaced. + * Once the RCU process has completed the unmap @unmap_addr is + * cleared. + */ typedef struct VhostUserHostNotifier { struct rcu_head rcu; MemoryRegion mr; void *addr; void *unmap_addr; + int idx; } VhostUserHostNotifier; +/** + * VhostUserState - shared state for all vhost-user devices + * @chr: the character backend for the socket + * @notifiers: GPtrArray of @VhostUserHostnotifier + * @memory_slots: + */ typedef struct VhostUserState { CharBackend *chr; - VhostUserHostNotifier notifier[VIRTIO_QUEUE_MAX]; + GPtrArray *notifiers; int memory_slots; bool supports_config; } VhostUserState; +/** + * vhost_user_init() - initialise shared vhost_user state + * @user: allocated area for storing shared state + * @chr: the chardev for the vhost socket + * @errp: error handle + * + * User can either directly g_new() space for the state or embed + * VhostUserState in their larger device structure and just point to + * it. + * + * Return: true on success, false on error while setting errp. + */ bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp); + +/** + * vhost_user_cleanup() - cleanup state + * @user: ptr to use state + * + * Cleans up shared state and notifiers, callee is responsible for + * freeing the @VhostUserState memory itself. + */ void vhost_user_cleanup(VhostUserState *user); #endif