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Re: [Qemu-devel] [PATCH v4] tests/vhost-user-bridge: implement logging o
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From: |
Michael S. Tsirkin |
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Subject: |
Re: [Qemu-devel] [PATCH v4] tests/vhost-user-bridge: implement logging of dirty pages |
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Date: |
Tue, 17 Nov 2015 13:04:33 +0200 |
On Tue, Nov 17, 2015 at 12:04:06PM +0200, Victor Kaplansky wrote:
> During migration devices continue writing to the guest's memory.
> The writes has to be reported to QEMU. This change implements
> minimal support in vhost-user-bridge required for successful
> migration of a guest with virtio-net device.
>
> Signed-off-by: Victor Kaplansky <address@hidden>
> ---
> v4:
> - implement set_vring_enable()
> - stop the device on vubr_get_vring_base_exec() and
> start on setting kick_fd as a work-around to QEMU bug
> enabling vrings too early.
You do want to address that FIXME but at least it's
a documented bug.
> v3:
> - Get rid of vhost_log_chunk_t. Just use uint8_t.
> - Implement vubr_set_log_fd_exec().
> - Kick the log if log_call_fd has been set up.
> - Mark bits in log table atomically to enable more then one
> simultaneous vhost-user backend.
> - Fix the calculations of required log table size in an
> assert.
> - Fix the coding style: only single space before assignment
> operator.
> - Add a comment on the hack to determine that queues are
> ready for processing.
> - Other minor cosmetic fixes.
> v2:
> - use log_guest_addr for used ring reported by qemu instead of
> translating.
> - use mmap_size and mmap_offset defined in new
> VHOST_USER_SET_LOG_BASE interface. See the patch
> "vhost-user: modify SET_LOG_BASE to pass mmap size and
> offset".
> - start logging dirty pages only after the appropriate feature
> is set by a VHOST_USER_GET_PROTOCOL_FEATURES request.
> - updated TODO list.
>
> tests/vhost-user-bridge.c | 220
> ++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 195 insertions(+), 25 deletions(-)
>
> diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
> index 864f69e..7bdfc98 100644
> --- a/tests/vhost-user-bridge.c
> +++ b/tests/vhost-user-bridge.c
> @@ -13,16 +13,22 @@
> /*
> * TODO:
> * - main should get parameters from the command line.
> - * - implement all request handlers.
> + * - implement all request handlers. Still not implemented:
> + * vubr_get_queue_num_exec()
> + * vubr_send_rarp_exec()
> * - test for broken requests and virtqueue.
> * - implement features defined by Virtio 1.0 spec.
> * - support mergeable buffers and indirect descriptors.
> - * - implement RESET_DEVICE request.
> * - implement clean shutdown.
> * - implement non-blocking writes to UDP backend.
> * - implement polling strategy.
> + * - implement clean starting/stopping of vq processing
> + * - implement clean starting/stopping of used and buffers
> + * dirty page logging.
> */
>
> +#define _FILE_OFFSET_BITS 64
> +
> #include <stddef.h>
> #include <assert.h>
> #include <stdio.h>
> @@ -166,6 +172,8 @@ typedef struct VubrVirtq {
> struct vring_desc *desc;
> struct vring_avail *avail;
> struct vring_used *used;
> + uint64_t log_guest_addr;
> + int enable;
> } VubrVirtq;
>
> /* Based on qemu/hw/virtio/vhost-user.c */
> @@ -173,6 +181,8 @@ typedef struct VubrVirtq {
> #define VHOST_MEMORY_MAX_NREGIONS 8
> #define VHOST_USER_F_PROTOCOL_FEATURES 30
>
> +#define VHOST_LOG_PAGE 4096
> +
> enum VhostUserProtocolFeature {
> VHOST_USER_PROTOCOL_F_MQ = 0,
> VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
> @@ -220,6 +230,11 @@ typedef struct VhostUserMemory {
> VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
> } VhostUserMemory;
>
> +typedef struct VhostUserLog {
> + uint64_t mmap_size;
> + uint64_t mmap_offset;
> +} VhostUserLog;
> +
> typedef struct VhostUserMsg {
> VhostUserRequest request;
>
> @@ -234,6 +249,7 @@ typedef struct VhostUserMsg {
> struct vhost_vring_state state;
> struct vhost_vring_addr addr;
> VhostUserMemory memory;
> + VhostUserLog log;
> } payload;
> int fds[VHOST_MEMORY_MAX_NREGIONS];
> int fd_num;
> @@ -265,8 +281,13 @@ typedef struct VubrDev {
> uint32_t nregions;
> VubrDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
> VubrVirtq vq[MAX_NR_VIRTQUEUE];
> + int log_call_fd;
> + uint64_t log_size;
> + uint8_t *log_table;
> int backend_udp_sock;
> struct sockaddr_in backend_udp_dest;
> + int ready;
> + uint64_t features;
> } VubrDev;
>
> static const char *vubr_request_str[] = {
> @@ -368,7 +389,12 @@ vubr_message_read(int conn_fd, VhostUserMsg *vmsg)
>
> rc = recvmsg(conn_fd, &msg, 0);
>
> - if (rc <= 0) {
> + if (rc == 0) {
> + vubr_die("recvmsg");
> + fprintf(stderr, "Peer disconnected.\n");
> + exit(1);
> + }
> + if (rc < 0) {
> vubr_die("recvmsg");
> }
>
> @@ -395,7 +421,12 @@ vubr_message_read(int conn_fd, VhostUserMsg *vmsg)
>
> if (vmsg->size) {
> rc = read(conn_fd, &vmsg->payload, vmsg->size);
> - if (rc <= 0) {
> + if (rc == 0) {
> + vubr_die("recvmsg");
> + fprintf(stderr, "Peer disconnected.\n");
> + exit(1);
> + }
> + if (rc < 0) {
> vubr_die("recvmsg");
> }
>
> @@ -455,6 +486,16 @@ vubr_consume_raw_packet(VubrDev *dev, uint8_t *buf,
> uint32_t len)
> vubr_backend_udp_sendbuf(dev, buf + hdrlen, len - hdrlen);
> }
>
> +/* Kick the log_call_fd if required. */
> +static void
> +vubr_log_kick(VubrDev *dev)
> +{
> + if (dev->log_call_fd != -1) {
> + DPRINT("Kicking the QEMU's log...\n");
> + eventfd_write(dev->log_call_fd, 1);
> + }
> +}
> +
> /* Kick the guest if necessary. */
> static void
> vubr_virtqueue_kick(VubrVirtq *vq)
> @@ -466,11 +507,39 @@ vubr_virtqueue_kick(VubrVirtq *vq)
> }
>
> static void
> +vubr_log_page(uint8_t *log_table, uint64_t page)
> +{
> + DPRINT("Logged dirty guest page: %"PRId64"\n", page);
> + atomic_or(&log_table[page / 8], 1 << (page % 8));
One thing you definitely want here is a check
against log size.
Otherwise it's a security hole:
remote can corrupt your memory by making you
set random bits outside the mapped buffer.
What to do on error? Probably abort.
> +}
> +
> +static void
> +vubr_log_write(VubrDev *dev, uint64_t address, uint64_t length)
> +{
> + uint64_t page;
> +
> + if (!(dev->features & (1ULL << VHOST_F_LOG_ALL)) ||
> + !dev->log_table || !length) {
> + return;
> + }
> +
> + assert(dev->log_size > ((address + length - 1) / VHOST_LOG_PAGE / 8));
> +
> + page = address / VHOST_LOG_PAGE;
> + while (page * VHOST_LOG_PAGE < address + length) {
> + vubr_log_page(dev->log_table, page);
> + page += VHOST_LOG_PAGE;
> + }
> + vubr_log_kick(dev);
> +}
> +
> +static void
> vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t *buf, int32_t len)
> {
> - struct vring_desc *desc = vq->desc;
> + struct vring_desc *desc = vq->desc;
> struct vring_avail *avail = vq->avail;
> - struct vring_used *used = vq->used;
> + struct vring_used *used = vq->used;
> + uint64_t log_guest_addr = vq->log_guest_addr;
>
> unsigned int size = vq->size;
>
> @@ -510,6 +579,7 @@ vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t
> *buf, int32_t len)
>
> if (len <= chunk_len) {
> memcpy(chunk_start, buf, len);
> + vubr_log_write(dev, desc[i].addr, len);
> } else {
> fprintf(stderr,
> "Received too long packet from the backend. Dropping...\n");
> @@ -519,11 +589,17 @@ vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t
> *buf, int32_t len)
> /* Add descriptor to the used ring. */
> used->ring[u_index].id = d_index;
> used->ring[u_index].len = len;
> + vubr_log_write(dev,
> + log_guest_addr + offsetof(struct vring_used,
> ring[u_index]),
> + sizeof(used->ring[u_index]));
>
> vq->last_avail_index++;
> vq->last_used_index++;
>
> atomic_mb_set(&used->idx, vq->last_used_index);
> + vubr_log_write(dev,
> + log_guest_addr + offsetof(struct vring_used, idx),
> + sizeof(used->idx));
>
> /* Kick the guest if necessary. */
> vubr_virtqueue_kick(vq);
> @@ -532,9 +608,10 @@ vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t
> *buf, int32_t len)
> static int
> vubr_process_desc(VubrDev *dev, VubrVirtq *vq)
> {
> - struct vring_desc *desc = vq->desc;
> + struct vring_desc *desc = vq->desc;
> struct vring_avail *avail = vq->avail;
> - struct vring_used *used = vq->used;
> + struct vring_used *used = vq->used;
> + uint64_t log_guest_addr = vq->log_guest_addr;
>
> unsigned int size = vq->size;
>
> @@ -552,6 +629,8 @@ vubr_process_desc(VubrDev *dev, VubrVirtq *vq)
> void *chunk_start = (void *)gpa_to_va(dev, desc[i].addr);
> uint32_t chunk_len = desc[i].len;
>
> + assert(!(desc[i].flags & VRING_DESC_F_WRITE));
> +
> if (len + chunk_len < buf_size) {
> memcpy(buf + len, chunk_start, chunk_len);
> DPRINT("%d ", chunk_len);
> @@ -577,6 +656,9 @@ vubr_process_desc(VubrDev *dev, VubrVirtq *vq)
> /* Add descriptor to the used ring. */
> used->ring[u_index].id = d_index;
> used->ring[u_index].len = len;
> + vubr_log_write(dev,
> + log_guest_addr + offsetof(struct vring_used,
> ring[u_index]),
> + sizeof(used->ring[u_index]));
>
> vubr_consume_raw_packet(dev, buf, len);
>
> @@ -588,6 +670,7 @@ vubr_process_avail(VubrDev *dev, VubrVirtq *vq)
> {
> struct vring_avail *avail = vq->avail;
> struct vring_used *used = vq->used;
> + uint64_t log_guest_addr = vq->log_guest_addr;
>
> while (vq->last_avail_index != atomic_mb_read(&avail->idx)) {
> vubr_process_desc(dev, vq);
> @@ -596,6 +679,9 @@ vubr_process_avail(VubrDev *dev, VubrVirtq *vq)
> }
>
> atomic_mb_set(&used->idx, vq->last_used_index);
> + vubr_log_write(dev,
> + log_guest_addr + offsetof(struct vring_used, idx),
> + sizeof(used->idx));
> }
>
> static void
> @@ -609,6 +695,10 @@ vubr_backend_recv_cb(int sock, void *ctx)
> int buflen = sizeof(buf);
> int len;
>
> + if (!dev->ready) {
> + return;
> + }
> +
> DPRINT("\n\n *** IN UDP RECEIVE CALLBACK ***\n\n");
>
> uint16_t avail_index = atomic_mb_read(&rx_vq->avail->idx);
> @@ -656,14 +746,14 @@ vubr_get_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> vmsg->payload.u64 =
> ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
> - (1ULL << VIRTIO_NET_F_CTRL_VQ) |
> - (1ULL << VIRTIO_NET_F_CTRL_RX) |
> - (1ULL << VHOST_F_LOG_ALL));
> + (1ULL << VHOST_F_LOG_ALL) |
> + (1ULL << VHOST_USER_F_PROTOCOL_FEATURES));
> +
> vmsg->size = sizeof(vmsg->payload.u64);
>
> DPRINT("Sending back to guest u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
>
> - /* reply */
> + /* Reply */
> return 1;
> }
>
> @@ -671,6 +761,7 @@ static int
> vubr_set_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
> + dev->features = vmsg->payload.u64;
> return 0;
> }
>
> @@ -680,10 +771,28 @@ vubr_set_owner_exec(VubrDev *dev, VhostUserMsg *vmsg)
> return 0;
> }
>
> +static void
> +vubr_close_log(VubrDev *dev)
> +{
> + if (dev->log_table) {
> + if (munmap(dev->log_table, dev->log_size) != 0) {
> + vubr_die("munmap()");
> + }
> +
> + dev->log_table = 0;
> + }
> + if (dev->log_call_fd != -1) {
> + close(dev->log_call_fd);
> + dev->log_call_fd = -1;
> + }
> +}
> +
> static int
> vubr_reset_device_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - DPRINT("Function %s() not implemented yet.\n", __func__);
> + vubr_close_log(dev);
> + dev->ready = 0;
> + dev->features = 0;
> return 0;
> }
>
> @@ -710,9 +819,9 @@ vubr_set_mem_table_exec(VubrDev *dev, VhostUserMsg *vmsg)
> DPRINT(" mmap_offset 0x%016"PRIx64"\n",
> msg_region->mmap_offset);
>
> - dev_region->gpa = msg_region->guest_phys_addr;
> - dev_region->size = msg_region->memory_size;
> - dev_region->qva = msg_region->userspace_addr;
> + dev_region->gpa = msg_region->guest_phys_addr;
> + dev_region->size = msg_region->memory_size;
> + dev_region->qva = msg_region->userspace_addr;
> dev_region->mmap_offset = msg_region->mmap_offset;
>
> /* We don't use offset argument of mmap() since the
> @@ -736,14 +845,38 @@ vubr_set_mem_table_exec(VubrDev *dev, VhostUserMsg
> *vmsg)
> static int
> vubr_set_log_base_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - DPRINT("Function %s() not implemented yet.\n", __func__);
> - return 0;
> + int fd;
> + uint64_t log_mmap_size, log_mmap_offset;
> + void *rc;
> +
> + assert(vmsg->fd_num == 1);
> + fd = vmsg->fds[0];
> +
> + assert(vmsg->size == sizeof(vmsg->payload.log));
> + log_mmap_offset = vmsg->payload.log.mmap_offset;
> + log_mmap_size = vmsg->payload.log.mmap_size;
> + DPRINT("Log mmap_offset: %"PRId64"\n", log_mmap_offset);
> + DPRINT("Log mmap_size: %"PRId64"\n", log_mmap_size);
> +
> + rc = mmap(0, log_mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
> + log_mmap_offset);
> + if (rc == MAP_FAILED) {
> + vubr_die("mmap");
> + }
> + dev->log_table = rc;
> + dev->log_size = log_mmap_size;
> +
> + vmsg->size = sizeof(vmsg->payload.u64);
> + /* Reply */
> + return 1;
> }
>
> static int
> vubr_set_log_fd_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - DPRINT("Function %s() not implemented yet.\n", __func__);
> + assert(vmsg->fd_num == 1);
> + dev->log_call_fd = vmsg->fds[0];
> + DPRINT("Got log_call_fd: %d\n", vmsg->fds[0]);
> return 0;
> }
>
> @@ -777,6 +910,7 @@ vubr_set_vring_addr_exec(VubrDev *dev, VhostUserMsg *vmsg)
> vq->desc = (struct vring_desc *)qva_to_va(dev, vra->desc_user_addr);
> vq->used = (struct vring_used *)qva_to_va(dev, vra->used_user_addr);
> vq->avail = (struct vring_avail *)qva_to_va(dev, vra->avail_user_addr);
> + vq->log_guest_addr = vra->log_guest_addr;
>
> DPRINT("Setting virtq addresses:\n");
> DPRINT(" vring_desc at %p\n", vq->desc);
> @@ -803,8 +937,18 @@ vubr_set_vring_base_exec(VubrDev *dev, VhostUserMsg
> *vmsg)
> static int
> vubr_get_vring_base_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - DPRINT("Function %s() not implemented yet.\n", __func__);
> - return 0;
> + unsigned int index = vmsg->payload.state.index;
> +
> + DPRINT("State.index: %d\n", index);
> + vmsg->payload.state.num = dev->vq[index].last_avail_index;
> + vmsg->size = sizeof(vmsg->payload.state);
> + /* FIXME: this is a work-around for a bug in QEMU enabling
> + * too early vrings. When protocol features are enabled,
> + * we have to respect * VHOST_USER_SET_VRING_ENABLE request. */
> + dev->ready = 0;
> +
> + /* Reply */
> + return 1;
> }
>
> static int
> @@ -829,7 +973,17 @@ vubr_set_vring_kick_exec(VubrDev *dev, VhostUserMsg
> *vmsg)
> DPRINT("Waiting for kicks on fd: %d for vq: %d\n",
> dev->vq[index].kick_fd, index);
> }
> + /* We temporarily use this hack to determine that both TX and RX
> + * queues are set up and ready for processing.
> + * FIXME: we need to rely in VHOST_USER_SET_VRING_ENABLE and
> + * actual kicks. */
And then ready flag will be per vq. Yes.
> + if (dev->vq[0].kick_fd != -1 &&
> + dev->vq[1].kick_fd != -1) {
> + dev->ready = 1;
> + DPRINT("vhost-user-bridge is ready for processing queues.\n");
> + }
> return 0;
> +
> }
>
> static int
> @@ -858,9 +1012,12 @@ vubr_set_vring_err_exec(VubrDev *dev, VhostUserMsg
> *vmsg)
> static int
> vubr_get_protocol_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - /* FIXME: unimplented */
> + vmsg->payload.u64 = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD;
> DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
> - return 0;
> + vmsg->size = sizeof(vmsg->payload.u64);
> +
> + /* Reply */
> + return 1;
> }
>
> static int
> @@ -881,7 +1038,12 @@ vubr_get_queue_num_exec(VubrDev *dev, VhostUserMsg
> *vmsg)
> static int
> vubr_set_vring_enable_exec(VubrDev *dev, VhostUserMsg *vmsg)
> {
> - DPRINT("Function %s() not implemented yet.\n", __func__);
> + unsigned int index = vmsg->payload.state.index;
> + unsigned int enable = vmsg->payload.state.num;
> +
> + DPRINT("State.index: %d\n", index);
> + DPRINT("State.enable: %d\n", enable);
> + dev->vq[index].enable = enable;
> return 0;
> }
>
> @@ -987,7 +1149,7 @@ vubr_accept_cb(int sock, void *ctx)
> socklen_t len = sizeof(un);
>
> conn_fd = accept(sock, (struct sockaddr *) &un, &len);
> - if (conn_fd == -1) {
> + if (conn_fd == -1) {
> vubr_die("accept()");
> }
> DPRINT("Got connection from remote peer on sock %d\n", conn_fd);
> @@ -1009,9 +1171,17 @@ vubr_new(const char *path)
> .size = 0,
> .last_avail_index = 0, .last_used_index = 0,
> .desc = 0, .avail = 0, .used = 0,
> + .enable = 0,
> };
> }
>
> + /* Init log */
> + dev->log_call_fd = -1;
> + dev->log_size = 0;
> + dev->log_table = 0;
> + dev->ready = 0;
> + dev->features = 0;
> +
> /* Get a UNIX socket. */
> dev->sock = socket(AF_UNIX, SOCK_STREAM, 0);
> if (dev->sock == -1) {
> --
> --Victor