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Re: [Qemu-devel] [PATCH v5 09/29] postcopy: Allow registering of fd hand
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v5 09/29] postcopy: Allow registering of fd handler |
Date: |
Tue, 13 Mar 2018 22:34:17 +0200 |
On Mon, Mar 12, 2018 at 05:21:04PM +0000, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Allow other userfaultfd's to be registered into the fault thread
> so that handlers for shared memory can get responses.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reviewed-by: Peter Xu <address@hidden>
new blank line at EOF errors.
> ---
> migration/migration.c | 6 ++
> migration/migration.h | 2 +
> migration/postcopy-ram.c | 210
> +++++++++++++++++++++++++++++++++++------------
> migration/postcopy-ram.h | 21 +++++
> migration/trace-events | 2 +
> 5 files changed, 188 insertions(+), 53 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 6a4780ef6f..1f22f463d3 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -155,6 +155,8 @@ MigrationIncomingState
> *migration_incoming_get_current(void)
> if (!once) {
> mis_current.state = MIGRATION_STATUS_NONE;
> memset(&mis_current, 0, sizeof(MigrationIncomingState));
> + mis_current.postcopy_remote_fds = g_array_new(FALSE, TRUE,
> + sizeof(struct
> PostCopyFD));
> qemu_mutex_init(&mis_current.rp_mutex);
> qemu_event_init(&mis_current.main_thread_load_event, false);
> once = true;
> @@ -177,6 +179,10 @@ void migration_incoming_state_destroy(void)
> qemu_fclose(mis->from_src_file);
> mis->from_src_file = NULL;
> }
> + if (mis->postcopy_remote_fds) {
> + g_array_free(mis->postcopy_remote_fds, TRUE);
> + mis->postcopy_remote_fds = NULL;
> + }
>
> qemu_event_reset(&mis->main_thread_load_event);
> }
> diff --git a/migration/migration.h b/migration/migration.h
> index 08c5d2ded1..d02a759331 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -51,6 +51,8 @@ struct MigrationIncomingState {
> QemuMutex rp_mutex; /* We send replies from multiple threads */
> void *postcopy_tmp_page;
> void *postcopy_tmp_zero_page;
> + /* PostCopyFD's for external userfaultfds & handlers of shared memory */
> + GArray *postcopy_remote_fds;
>
> QEMUBH *bh;
>
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 1089814d54..4ab1b7d36d 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -533,29 +533,44 @@ static void *postcopy_ram_fault_thread(void *opaque)
> MigrationIncomingState *mis = opaque;
> struct uffd_msg msg;
> int ret;
> + size_t index;
> RAMBlock *rb = NULL;
> RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */
>
> trace_postcopy_ram_fault_thread_entry();
> qemu_sem_post(&mis->fault_thread_sem);
>
> + struct pollfd *pfd;
> + size_t pfd_len = 2 + mis->postcopy_remote_fds->len;
> +
> + pfd = g_new0(struct pollfd, pfd_len);
> +
> + pfd[0].fd = mis->userfault_fd;
> + pfd[0].events = POLLIN;
> + pfd[1].fd = mis->userfault_event_fd;
> + pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
> + trace_postcopy_ram_fault_thread_fds_core(pfd[0].fd, pfd[1].fd);
> + for (index = 0; index < mis->postcopy_remote_fds->len; index++) {
> + struct PostCopyFD *pcfd = &g_array_index(mis->postcopy_remote_fds,
> + struct PostCopyFD, index);
> + pfd[2 + index].fd = pcfd->fd;
> + pfd[2 + index].events = POLLIN;
> + trace_postcopy_ram_fault_thread_fds_extra(2 + index, pcfd->idstr,
> + pcfd->fd);
> + }
> +
> while (true) {
> ram_addr_t rb_offset;
> - struct pollfd pfd[2];
> + int poll_result;
>
> /*
> * We're mainly waiting for the kernel to give us a faulting HVA,
> * however we can be told to quit via userfault_quit_fd which is
> * an eventfd
> */
> - pfd[0].fd = mis->userfault_fd;
> - pfd[0].events = POLLIN;
> - pfd[0].revents = 0;
> - pfd[1].fd = mis->userfault_event_fd;
> - pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
> - pfd[1].revents = 0;
> -
> - if (poll(pfd, 2, -1 /* Wait forever */) == -1) {
> +
> + poll_result = poll(pfd, pfd_len, -1 /* Wait forever */);
> + if (poll_result == -1) {
> error_report("%s: userfault poll: %s", __func__,
> strerror(errno));
> break;
> }
> @@ -575,57 +590,117 @@ static void *postcopy_ram_fault_thread(void *opaque)
> }
> }
>
> - ret = read(mis->userfault_fd, &msg, sizeof(msg));
> - if (ret != sizeof(msg)) {
> - if (errno == EAGAIN) {
> - /*
> - * if a wake up happens on the other thread just after
> - * the poll, there is nothing to read.
> - */
> - continue;
> + if (pfd[0].revents) {
> + poll_result--;
> + ret = read(mis->userfault_fd, &msg, sizeof(msg));
> + if (ret != sizeof(msg)) {
> + if (errno == EAGAIN) {
> + /*
> + * if a wake up happens on the other thread just after
> + * the poll, there is nothing to read.
> + */
> + continue;
> + }
> + if (ret < 0) {
> + error_report("%s: Failed to read full userfault "
> + "message: %s",
> + __func__, strerror(errno));
> + break;
> + } else {
> + error_report("%s: Read %d bytes from userfaultfd "
> + "expected %zd",
> + __func__, ret, sizeof(msg));
> + break; /* Lost alignment, don't know what we'd read next
> */
> + }
> }
> - if (ret < 0) {
> - error_report("%s: Failed to read full userfault message: %s",
> - __func__, strerror(errno));
> - break;
> - } else {
> - error_report("%s: Read %d bytes from userfaultfd expected
> %zd",
> - __func__, ret, sizeof(msg));
> - break; /* Lost alignment, don't know what we'd read next */
> + if (msg.event != UFFD_EVENT_PAGEFAULT) {
> + error_report("%s: Read unexpected event %ud from
> userfaultfd",
> + __func__, msg.event);
> + continue; /* It's not a page fault, shouldn't happen */
> }
> - }
> - if (msg.event != UFFD_EVENT_PAGEFAULT) {
> - error_report("%s: Read unexpected event %ud from userfaultfd",
> - __func__, msg.event);
> - continue; /* It's not a page fault, shouldn't happen */
> - }
>
> - rb = qemu_ram_block_from_host(
> - (void *)(uintptr_t)msg.arg.pagefault.address,
> - true, &rb_offset);
> - if (!rb) {
> - error_report("postcopy_ram_fault_thread: Fault outside guest: %"
> - PRIx64, (uint64_t)msg.arg.pagefault.address);
> - break;
> - }
> + rb = qemu_ram_block_from_host(
> + (void *)(uintptr_t)msg.arg.pagefault.address,
> + true, &rb_offset);
> + if (!rb) {
> + error_report("postcopy_ram_fault_thread: Fault outside
> guest: %"
> + PRIx64, (uint64_t)msg.arg.pagefault.address);
> + break;
> + }
>
> - rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
> - trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
> + rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
> +
> trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
> qemu_ram_get_idstr(rb),
> rb_offset);
> + /*
> + * Send the request to the source - we want to request one
> + * of our host page sizes (which is >= TPS)
> + */
> + if (rb != last_rb) {
> + last_rb = rb;
> + migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
> + rb_offset, qemu_ram_pagesize(rb));
> + } else {
> + /* Save some space */
> + migrate_send_rp_req_pages(mis, NULL,
> + rb_offset, qemu_ram_pagesize(rb));
> + }
> + }
>
> - /*
> - * Send the request to the source - we want to request one
> - * of our host page sizes (which is >= TPS)
> - */
> - if (rb != last_rb) {
> - last_rb = rb;
> - migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
> - rb_offset, qemu_ram_pagesize(rb));
> - } else {
> - /* Save some space */
> - migrate_send_rp_req_pages(mis, NULL,
> - rb_offset, qemu_ram_pagesize(rb));
> + /* Now handle any requests from external processes on shared memory
> */
> + /* TODO: May need to handle devices deregistering during postcopy */
> + for (index = 2; index < pfd_len && poll_result; index++) {
> + if (pfd[index].revents) {
> + struct PostCopyFD *pcfd =
> + &g_array_index(mis->postcopy_remote_fds,
> + struct PostCopyFD, index - 2);
> +
> + poll_result--;
> + if (pfd[index].revents & POLLERR) {
> + error_report("%s: POLLERR on poll %zd fd=%d",
> + __func__, index, pcfd->fd);
> + pfd[index].events = 0;
> + continue;
> + }
> +
> + ret = read(pcfd->fd, &msg, sizeof(msg));
> + if (ret != sizeof(msg)) {
> + if (errno == EAGAIN) {
> + /*
> + * if a wake up happens on the other thread just
> after
> + * the poll, there is nothing to read.
> + */
> + continue;
> + }
> + if (ret < 0) {
> + error_report("%s: Failed to read full userfault "
> + "message: %s (shared) revents=%d",
> + __func__, strerror(errno),
> + pfd[index].revents);
> + /*TODO: Could just disable this sharer */
> + break;
> + } else {
> + error_report("%s: Read %d bytes from userfaultfd "
> + "expected %zd (shared)",
> + __func__, ret, sizeof(msg));
> + /*TODO: Could just disable this sharer */
> + break; /*Lost alignment,don't know what we'd read
> next*/
> + }
> + }
> + if (msg.event != UFFD_EVENT_PAGEFAULT) {
> + error_report("%s: Read unexpected event %ud "
> + "from userfaultfd (shared)",
> + __func__, msg.event);
> + continue; /* It's not a page fault, shouldn't happen */
> + }
> + /* Call the device handler registered with us */
> + ret = pcfd->handler(pcfd, &msg);
> + if (ret) {
> + error_report("%s: Failed to resolve shared fault on
> %zd/%s",
> + __func__, index, pcfd->idstr);
> + /* TODO: Fail? Disable this sharer? */
> + }
> + }
> }
> }
> trace_postcopy_ram_fault_thread_exit();
> @@ -970,3 +1045,32 @@ PostcopyState postcopy_state_set(PostcopyState
> new_state)
> {
> return atomic_xchg(&incoming_postcopy_state, new_state);
> }
> +
> +/* Register a handler for external shared memory postcopy
> + * called on the destination.
> + */
> +void postcopy_register_shared_ufd(struct PostCopyFD *pcfd)
> +{
> + MigrationIncomingState *mis = migration_incoming_get_current();
> +
> + mis->postcopy_remote_fds = g_array_append_val(mis->postcopy_remote_fds,
> + *pcfd);
> +}
> +
> +/* Unregister a handler for external shared memory postcopy
> + */
> +void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
> +{
> + guint i;
> + MigrationIncomingState *mis = migration_incoming_get_current();
> + GArray *pcrfds = mis->postcopy_remote_fds;
> +
> + for (i = 0; i < pcrfds->len; i++) {
> + struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD,
> i);
> + if (cur->fd == pcfd->fd) {
> + mis->postcopy_remote_fds = g_array_remove_index(pcrfds, i);
> + return;
> + }
> + }
> +}
> +
> diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
> index 0421c98d57..f21eef6702 100644
> --- a/migration/postcopy-ram.h
> +++ b/migration/postcopy-ram.h
> @@ -143,4 +143,25 @@ void postcopy_remove_notifier(NotifierWithReturn *n);
> /* Call the notifier list set by postcopy_add_start_notifier */
> int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
>
> +struct PostCopyFD;
> +
> +/* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
> +typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
> +
> +struct PostCopyFD {
> + int fd;
> + /* Data to pass to handler */
> + void *data;
> + /* Handler to be called whenever we get a poll event */
> + pcfdhandler handler;
> + /* A string to use in error messages */
> + const char *idstr;
> +};
> +
> +/* Register a userfaultfd owned by an external process for
> + * shared memory.
> + */
> +void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
> +void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
> +
> #endif
> diff --git a/migration/trace-events b/migration/trace-events
> index 93961dea16..1e617ad7a6 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -190,6 +190,8 @@ postcopy_place_page_zero(void *host_addr) "host=%p"
> postcopy_ram_enable_notify(void) ""
> postcopy_ram_fault_thread_entry(void) ""
> postcopy_ram_fault_thread_exit(void) ""
> +postcopy_ram_fault_thread_fds_core(int baseufd, int quitfd) "ufd: %d quitfd:
> %d"
> +postcopy_ram_fault_thread_fds_extra(size_t index, const char *name, int fd)
> "%zd/%s: %d"
> postcopy_ram_fault_thread_quit(void) ""
> postcopy_ram_fault_thread_request(uint64_t hostaddr, const char *ramblock,
> size_t offset) "Request for HVA=0x%" PRIx64 " rb=%s offset=0x%zx"
> postcopy_ram_incoming_cleanup_closeuf(void) ""
> --
> 2.14.3
- [Qemu-devel] [PATCH v5 05/29] postcopy: Add vhost-user flag for postcopy and check it, (continued)
- [Qemu-devel] [PATCH v5 05/29] postcopy: Add vhost-user flag for postcopy and check it, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 03/29] postcopy: use UFFDIO_ZEROPAGE only when available, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 01/29] migrate: Update ram_block_discard_range for shared, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 02/29] qemu_ram_block_host_offset, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 04/29] postcopy: Add notifier chain, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 07/29] libvhost-user: Support sending fds back to qemu, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 08/29] libvhost-user: Open userfaultfd, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 06/29] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 10/29] vhost+postcopy: Register shared ufd with postcopy, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 09/29] postcopy: Allow registering of fd handler, Dr. David Alan Gilbert (git), 2018/03/12
- Re: [Qemu-devel] [PATCH v5 09/29] postcopy: Allow registering of fd handler,
Michael S. Tsirkin <=
- [Qemu-devel] [PATCH v5 11/29] vhost+postcopy: Transmit 'listen' to slave, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 12/29] postcopy+vhost-user: Split set_mem_table for postcopy, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 13/29] migration/ram: ramblock_recv_bitmap_test_byte_offset, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 14/29] libvhost-user+postcopy: Register new regions with the ufd, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 15/29] vhost+postcopy: Send address back to qemu, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 18/29] vhost+postcopy: Resolve client address, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 16/29] vhost+postcopy: Stash RAMBlock and offset, Dr. David Alan Gilbert (git), 2018/03/12
- [Qemu-devel] [PATCH v5 17/29] vhost+postcopy: Helper to send requests to source for shared pages, Dr. David Alan Gilbert (git), 2018/03/12