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Re: [PATCH 1/2] vhost-user: add a write-read lock
|
From: |
Michael S. Tsirkin |
|
Subject: |
Re: [PATCH 1/2] vhost-user: add a write-read lock |
|
Date: |
Sat, 20 Jul 2024 15:41:08 -0400 |
On Thu, Jul 11, 2024 at 06:44:23PM +0530, Prasad Pandit wrote:
> From: Prasad Pandit <pjp@fedoraproject.org>
>
> QEMU threads use vhost_user_write/read calls to send
> and receive messages from a vhost-user device. When multiple
> threads communicate with the same vhost-user device, they can
> receive each other's messages, resulting in an erroneous state.
>
> vhost_user_read_header:
> 700871,700871: Failed to read msg header. Flags 0x0 instead of 0x5.
> vhost_device_iotlb_miss:
> 700871,700871: Fail to update device iotlb
> vhost_user_postcopy_end:
> 700871,700900: Failed to receive reply to postcopy_end
> vhost_user_read_header:
> 700871,700871: Failed to read msg header. Flags 0x0 instead of 0x5.
>
> Here fault thread seems to end the postcopy migration while
> another thread is starting the vhost-user device.
>
> Add a rw lock to hold for one vhost_user_write/read cycle
> and avoid such race conditions.
>
> Suggested-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Prasad Pandit <pjp@fedoraproject.org>
> ---
> hw/virtio/vhost-user.c | 423 +++++++++++++++++++--------------
> include/hw/virtio/vhost-user.h | 3 +
> 2 files changed, 254 insertions(+), 172 deletions(-)
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 00561daa06..99881c487f 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -24,6 +24,7 @@
> #include "qemu/main-loop.h"
> #include "qemu/uuid.h"
> #include "qemu/sockets.h"
> +#include "qemu/lockable.h"
> #include "sysemu/runstate.h"
> #include "sysemu/cryptodev.h"
> #include "migration/postcopy-ram.h"
> @@ -433,6 +434,8 @@ int vhost_user_gpu_set_socket(struct vhost_dev *dev, int
> fd)
> static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
> struct vhost_log *log)
> {
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> int fds[VHOST_USER_MAX_RAM_SLOTS];
> size_t fd_num = 0;
> bool shmfd = virtio_has_feature(dev->protocol_features,
> @@ -455,23 +458,25 @@ static int vhost_user_set_log_base(struct vhost_dev
> *dev, uint64_t base,
> fds[fd_num++] = log->fd;
> }
>
> - ret = vhost_user_write(dev, &msg, fds, fd_num);
> - if (ret < 0) {
> - return ret;
> - }
> -
> - if (shmfd) {
> - msg.hdr.size = 0;
> - ret = vhost_user_read(dev, &msg);
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, fds, fd_num);
> if (ret < 0) {
> return ret;
> }
>
> - if (msg.hdr.request != VHOST_USER_SET_LOG_BASE) {
> - error_report("Received unexpected msg type. "
> - "Expected %d received %d",
> - VHOST_USER_SET_LOG_BASE, msg.hdr.request);
> - return -EPROTO;
> + if (shmfd) {
> + msg.hdr.size = 0;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + if (msg.hdr.request != VHOST_USER_SET_LOG_BASE) {
> + error_report("Received unexpected msg type. "
> + "Expected %d received %d",
> + VHOST_USER_SET_LOG_BASE, msg.hdr.request);
> + return -EPROTO;
> + }
> }
> }
>
> @@ -664,6 +669,7 @@ static int send_remove_regions(struct vhost_dev *dev,
> bool reply_supported)
> {
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> struct vhost_memory_region *shadow_reg;
> int i, fd, shadow_reg_idx, ret;
> ram_addr_t offset;
> @@ -685,16 +691,18 @@ static int send_remove_regions(struct vhost_dev *dev,
> vhost_user_fill_msg_region(®ion_buffer, shadow_reg, 0);
> msg->payload.mem_reg.region = region_buffer;
>
> - ret = vhost_user_write(dev, msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> -
> - if (reply_supported) {
> - ret = process_message_reply(dev, msg);
> - if (ret) {
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, msg, NULL, 0);
> + if (ret < 0) {
> return ret;
> }
> +
> + if (reply_supported) {
> + ret = process_message_reply(dev, msg);
> + if (ret) {
> + return ret;
> + }
> + }
> }
> }
>
> @@ -725,6 +733,9 @@ static int send_add_regions(struct vhost_dev *dev,
> VhostUserMsg msg_reply;
> VhostUserMemoryRegion region_buffer;
>
> + struct VhostUserState *us = u->user;
> + QEMU_LOCK_GUARD(&us->vhost_user_rw_lock);
> +
> for (i = 0; i < nr_add_reg; i++) {
> reg = add_reg[i].region;
> reg_idx = add_reg[i].reg_idx;
> @@ -893,6 +904,7 @@ static int vhost_user_set_mem_table_postcopy(struct
> vhost_dev *dev,
> bool config_mem_slots)
> {
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> int fds[VHOST_MEMORY_BASELINE_NREGIONS];
> size_t fd_num = 0;
> VhostUserMsg msg_reply;
> @@ -926,14 +938,16 @@ static int vhost_user_set_mem_table_postcopy(struct
> vhost_dev *dev,
> return ret;
> }
>
> - ret = vhost_user_write(dev, &msg, fds, fd_num);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, fds, fd_num);
> + if (ret < 0) {
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg_reply);
> - if (ret < 0) {
> - return ret;
> + ret = vhost_user_read(dev, &msg_reply);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> if (msg_reply.hdr.request != VHOST_USER_SET_MEM_TABLE) {
> @@ -1005,6 +1019,7 @@ static int vhost_user_set_mem_table(struct vhost_dev
> *dev,
> struct vhost_memory *mem)
> {
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> int fds[VHOST_MEMORY_BASELINE_NREGIONS];
> size_t fd_num = 0;
> bool do_postcopy = u->postcopy_listen && u->postcopy_fd.handler;
> @@ -1044,13 +1059,15 @@ static int vhost_user_set_mem_table(struct vhost_dev
> *dev,
> return ret;
> }
>
> - ret = vhost_user_write(dev, &msg, fds, fd_num);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, fds, fd_num);
> + if (ret < 0) {
> + return ret;
> + }
>
> - if (reply_supported) {
> - return process_message_reply(dev, &msg);
> + if (reply_supported) {
> + return process_message_reply(dev, &msg);
> + }
> }
> }
>
> @@ -1080,6 +1097,8 @@ static int vhost_user_set_vring_endian(struct vhost_dev
> *dev,
> static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t
> *u64)
> {
> int ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> VhostUserMsg msg = {
> .hdr.request = request,
> .hdr.flags = VHOST_USER_VERSION,
> @@ -1089,14 +1108,16 @@ static int vhost_user_get_u64(struct vhost_dev *dev,
> int request, uint64_t *u64)
> return 0;
> }
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> if (msg.hdr.request != request) {
> @@ -1129,6 +1150,8 @@ static int vhost_user_write_sync(struct vhost_dev *dev,
> VhostUserMsg *msg,
> bool wait_for_reply)
> {
> int ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
>
> if (wait_for_reply) {
> bool reply_supported = virtio_has_feature(dev->protocol_features,
> @@ -1138,25 +1161,27 @@ static int vhost_user_write_sync(struct vhost_dev
> *dev, VhostUserMsg *msg,
> }
> }
>
> - ret = vhost_user_write(dev, msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - if (wait_for_reply) {
> - uint64_t dummy;
> + if (wait_for_reply) {
> + uint64_t dummy;
>
> - if (msg->hdr.flags & VHOST_USER_NEED_REPLY_MASK) {
> - return process_message_reply(dev, msg);
> - }
> + if (msg->hdr.flags & VHOST_USER_NEED_REPLY_MASK) {
> + return process_message_reply(dev, msg);
> + }
>
> - /*
> - * We need to wait for a reply but the backend does not
> - * support replies for the command we just sent.
> - * Send VHOST_USER_GET_FEATURES which makes all backends
> - * send a reply.
> - */
> - return vhost_user_get_features(dev, &dummy);
> + /*
> + * We need to wait for a reply but the backend does not
> + * support replies for the command we just sent.
> + * Send VHOST_USER_GET_FEATURES which makes all backends
> + * send a reply.
> + */
> + return vhost_user_get_features(dev, &dummy);
> + }
> }
>
> return 0;
> @@ -1277,20 +1302,23 @@ static int vhost_user_get_vring_base(struct vhost_dev
> *dev,
> .hdr.size = sizeof(msg.payload.state),
> };
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
>
> 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) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_GET_VRING_BASE) {
> @@ -1661,6 +1689,7 @@ int vhost_user_get_shared_object(struct vhost_dev *dev,
> unsigned char *uuid,
> int *dmabuf_fd)
> {
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> CharBackend *chr = u->user->chr;
> int ret;
> VhostUserMsg msg = {
> @@ -1669,14 +1698,16 @@ int vhost_user_get_shared_object(struct vhost_dev
> *dev, unsigned char *uuid,
> };
> memcpy(msg.payload.object.uuid, uuid, sizeof(msg.payload.object.uuid));
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_GET_SHARED_OBJECT) {
> @@ -1858,6 +1889,7 @@ static int vhost_setup_backend_channel(struct vhost_dev
> *dev)
> .hdr.flags = VHOST_USER_VERSION,
> };
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> int sv[2], ret = 0;
> bool reply_supported = virtio_has_feature(dev->protocol_features,
>
> VHOST_USER_PROTOCOL_F_REPLY_ACK);
> @@ -1889,15 +1921,16 @@ static int vhost_setup_backend_channel(struct
> vhost_dev *dev)
> msg.hdr.flags |= VHOST_USER_NEED_REPLY_MASK;
> }
>
> - ret = vhost_user_write(dev, &msg, &sv[1], 1);
> - if (ret) {
> - goto out;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, &sv[1], 1);
> + if (ret) {
> + goto out;
> + }
>
> - if (reply_supported) {
> - ret = process_message_reply(dev, &msg);
> + if (reply_supported) {
> + ret = process_message_reply(dev, &msg);
> + }
> }
> -
> out:
> close(sv[1]);
> if (ret) {
> @@ -1985,6 +2018,7 @@ static int vhost_user_postcopy_advise(struct vhost_dev
> *dev, Error **errp)
> {
> #ifdef CONFIG_LINUX
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> CharBackend *chr = u->user->chr;
> int ufd;
> int ret;
> @@ -1993,16 +2027,18 @@ static int vhost_user_postcopy_advise(struct
> vhost_dev *dev, Error **errp)
> .hdr.flags = VHOST_USER_VERSION,
> };
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_setg(errp, "Failed to send postcopy_advise to vhost");
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_setg(errp, "Failed to send postcopy_advise to vhost");
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - error_setg(errp, "Failed to get postcopy_advise reply from vhost");
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + error_setg(errp, "Failed to get postcopy_advise reply from
> vhost");
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_POSTCOPY_ADVISE) {
> @@ -2051,16 +2087,19 @@ static int vhost_user_postcopy_listen(struct
> vhost_dev *dev, Error **errp)
>
> trace_vhost_user_postcopy_listen();
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_setg(errp, "Failed to send postcopy_listen to vhost");
> - return ret;
> - }
> + struct VhostUserState *us = u->user;
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_setg(errp, "Failed to send postcopy_listen to vhost");
> + return ret;
> + }
>
> - ret = process_message_reply(dev, &msg);
> - if (ret) {
> - error_setg(errp, "Failed to receive reply to postcopy_listen");
> - return ret;
> + ret = process_message_reply(dev, &msg);
> + if (ret) {
> + error_setg(errp, "Failed to receive reply to postcopy_listen");
> + return ret;
> + }
> }
>
> return 0;
> @@ -2077,19 +2116,22 @@ static int vhost_user_postcopy_end(struct vhost_dev
> *dev, Error **errp)
> };
> int ret;
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
>
> trace_vhost_user_postcopy_end_entry();
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_setg(errp, "Failed to send postcopy_end to vhost");
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_setg(errp, "Failed to send postcopy_end to vhost");
> + return ret;
> + }
>
> - ret = process_message_reply(dev, &msg);
> - if (ret) {
> - error_setg(errp, "Failed to receive reply to postcopy_end");
> - return ret;
> + ret = process_message_reply(dev, &msg);
> + if (ret) {
> + error_setg(errp, "Failed to receive reply to postcopy_end");
> + return ret;
> + }
> }
> postcopy_unregister_shared_ufd(&u->postcopy_fd);
> close(u->postcopy_fd.fd);
> @@ -2359,6 +2401,8 @@ static int vhost_user_net_set_mtu(struct vhost_dev
> *dev, uint16_t mtu)
> bool reply_supported = virtio_has_feature(dev->protocol_features,
>
> VHOST_USER_PROTOCOL_F_REPLY_ACK);
> int ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
>
> if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_NET_MTU)))
> {
> return 0;
> @@ -2372,14 +2416,16 @@ static int vhost_user_net_set_mtu(struct vhost_dev
> *dev, uint16_t mtu)
> msg.hdr.flags |= VHOST_USER_NEED_REPLY_MASK;
> }
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - /* If reply_ack supported, backend has to ack specified MTU is valid */
> - if (reply_supported) {
> - return process_message_reply(dev, &msg);
> + /* If reply_ack supported, backend has to ack specified MTU is valid
> */
> + if (reply_supported) {
> + return process_message_reply(dev, &msg);
> + }
> }
>
> return 0;
> @@ -2396,12 +2442,19 @@ static int vhost_user_send_device_iotlb_msg(struct
> vhost_dev *dev,
> .payload.iotlb = *imsg,
> };
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> +
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + ret = process_message_reply(dev, &msg);
> }
>
> - return process_message_reply(dev, &msg);
> + return ret;
> }
>
>
> @@ -2414,6 +2467,8 @@ static int vhost_user_get_config(struct vhost_dev *dev,
> uint8_t *config,
> uint32_t config_len, Error **errp)
> {
> int ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> VhostUserMsg msg = {
> .hdr.request = VHOST_USER_GET_CONFIG,
> .hdr.flags = VHOST_USER_VERSION,
> @@ -2430,16 +2485,19 @@ static int vhost_user_get_config(struct vhost_dev
> *dev, uint8_t *config,
>
> msg.payload.config.offset = 0;
> msg.payload.config.size = config_len;
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret, "vhost_get_config failed");
> - return ret;
> - }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret, "vhost_get_config failed");
> - return ret;
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "vhost_get_config failed");
> + return ret;
> + }
> +
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "vhost_get_config failed");
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_GET_CONFIG) {
> @@ -2464,6 +2522,8 @@ static int vhost_user_set_config(struct vhost_dev *dev,
> const uint8_t *data,
> {
> int ret;
> uint8_t *p;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> bool reply_supported = virtio_has_feature(dev->protocol_features,
>
> VHOST_USER_PROTOCOL_F_REPLY_ACK);
>
> @@ -2492,13 +2552,15 @@ static int vhost_user_set_config(struct vhost_dev
> *dev, const uint8_t *data,
> p = msg.payload.config.region;
> memcpy(p, data, size);
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - if (reply_supported) {
> - return process_message_reply(dev, &msg);
> + if (reply_supported) {
> + return process_message_reply(dev, &msg);
> + }
> }
>
> return 0;
> @@ -2509,6 +2571,8 @@ static int vhost_user_crypto_create_session(struct
> vhost_dev *dev,
> uint64_t *session_id)
> {
> int ret;
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> bool crypto_session = virtio_has_feature(dev->protocol_features,
> VHOST_USER_PROTOCOL_F_CRYPTO_SESSION);
> CryptoDevBackendSessionInfo *backend_info = session_info;
> @@ -2572,18 +2636,21 @@ static int vhost_user_crypto_create_session(struct
> vhost_dev *dev,
>
> msg.payload.session.op_code = backend_info->op_code;
> msg.payload.session.session_id = backend_info->session_id;
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_report("vhost_user_write() return %d, create session failed",
> - ret);
> - return ret;
> - }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - error_report("vhost_user_read() return %d, create session failed",
> - ret);
> - return ret;
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_report("vhost_user_write() return %d, create session
> failed",
> + ret);
> + return ret;
> + }
> +
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + error_report("vhost_user_read() return %d, create session
> failed",
> + ret);
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_CREATE_CRYPTO_SESSION) {
> @@ -2648,6 +2715,7 @@ static int vhost_user_get_inflight_fd(struct vhost_dev
> *dev,
> int fd;
> int ret;
> struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> CharBackend *chr = u->user->chr;
> VhostUserMsg msg = {
> .hdr.request = VHOST_USER_GET_INFLIGHT_FD,
> @@ -2662,14 +2730,16 @@ static int vhost_user_get_inflight_fd(struct
> vhost_dev *dev,
> return 0;
> }
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_GET_INFLIGHT_FD) {
> @@ -2757,6 +2827,7 @@ bool vhost_user_init(VhostUserState *user, CharBackend
> *chr, Error **errp)
> user->memory_slots = 0;
> user->notifiers = g_ptr_array_new_full(VIRTIO_QUEUE_MAX / 4,
> &vhost_user_state_destroy);
> + qemu_mutex_init(&user->vhost_user_rw_lock);
> return true;
> }
>
> @@ -2769,6 +2840,7 @@ void vhost_user_cleanup(VhostUserState *user)
> user->notifiers = (GPtrArray *) g_ptr_array_free(user->notifiers, true);
> memory_region_transaction_commit();
> user->chr = NULL;
> + qemu_mutex_destroy(&user->vhost_user_rw_lock);
> }
>
>
> @@ -2882,6 +2954,7 @@ static int vhost_user_set_device_state_fd(struct
> vhost_dev *dev,
> {
> int ret;
> struct vhost_user *vu = dev->opaque;
> + struct VhostUserState *us = vu->user;
> VhostUserMsg msg = {
> .hdr = {
> .request = VHOST_USER_SET_DEVICE_STATE_FD,
> @@ -2902,19 +2975,21 @@ static int vhost_user_set_device_state_fd(struct
> vhost_dev *dev,
> return -ENOTSUP;
> }
>
> - ret = vhost_user_write(dev, &msg, &fd, 1);
> - close(fd);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret,
> - "Failed to send SET_DEVICE_STATE_FD message");
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, &fd, 1);
> + close(fd);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret,
> + "Failed to send SET_DEVICE_STATE_FD message");
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret,
> - "Failed to receive SET_DEVICE_STATE_FD reply");
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret,
> + "Failed to receive SET_DEVICE_STATE_FD reply");
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_SET_DEVICE_STATE_FD) {
> @@ -2951,6 +3026,8 @@ static int vhost_user_set_device_state_fd(struct
> vhost_dev *dev,
>
> static int vhost_user_check_device_state(struct vhost_dev *dev, Error **errp)
> {
> + struct vhost_user *u = dev->opaque;
> + struct VhostUserState *us = u->user;
> int ret;
> VhostUserMsg msg = {
> .hdr = {
> @@ -2965,18 +3042,20 @@ static int vhost_user_check_device_state(struct
> vhost_dev *dev, Error **errp)
> return -ENOTSUP;
> }
>
> - ret = vhost_user_write(dev, &msg, NULL, 0);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret,
> - "Failed to send CHECK_DEVICE_STATE message");
> - return ret;
> - }
> + WITH_QEMU_LOCK_GUARD(&us->vhost_user_rw_lock) {
> + ret = vhost_user_write(dev, &msg, NULL, 0);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret,
> + "Failed to send CHECK_DEVICE_STATE message");
> + return ret;
> + }
>
> - ret = vhost_user_read(dev, &msg);
> - if (ret < 0) {
> - error_setg_errno(errp, -ret,
> - "Failed to receive CHECK_DEVICE_STATE reply");
> - return ret;
> + ret = vhost_user_read(dev, &msg);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret,
> + "Failed to receive CHECK_DEVICE_STATE reply");
> + return ret;
> + }
> }
>
> if (msg.hdr.request != VHOST_USER_CHECK_DEVICE_STATE) {
> diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
> index 324cd8663a..387ab6da2e 100644
> --- a/include/hw/virtio/vhost-user.h
> +++ b/include/hw/virtio/vhost-user.h
> @@ -67,6 +67,9 @@ typedef struct VhostUserState {
> GPtrArray *notifiers;
> int memory_slots;
> bool supports_config;
> +
> + /* Hold lock for vhost_user_write/read cycle */
> + QemuMutex vhost_user_rw_lock;
> } VhostUserState;
So it's not a rw lock. It's just a mutex.
Lock should be named after what they protect, not
after where they are held.
In this case, this ensures only 1 request is
outstanding at a time.
So vhost_user_request_reply_lock
>
> /**
> --
> 2.45.2
[PATCH 2/2] vhost: fail device start if iotlb update fails, Prasad Pandit, 2024/07/11
Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Peter Xu, 2024/07/11
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Prasad Pandit, 2024/07/15
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Peter Xu, 2024/07/15
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Prasad Pandit, 2024/07/16
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Peter Xu, 2024/07/16
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Michael S. Tsirkin, 2024/07/17
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Peter Xu, 2024/07/17
- Re: [PATCH 0/2] Postcopy migration and vhost-user errors, Michael S. Tsirkin, 2024/07/17