From 00fa4fc85b00f1a8a810068d158a7a66e88658eb Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 12 Mar 2018 17:21:04 +0000 Subject: postcopy: Allow registering of fd handler 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 Reviewed-by: Peter Xu Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- migration/migration.c | 6 ++ migration/migration.h | 2 + migration/postcopy-ram.c | 209 +++++++++++++++++++++++++++++++++++------------ migration/postcopy-ram.h | 21 +++++ migration/trace-events | 2 + 5 files changed, 187 insertions(+), 53 deletions(-) (limited to 'migration') 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..6ce157741f 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 +1045,31 @@ 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) "" -- cgit v1.2.1