On Mon, Mar 12, 2018 at 05:21:04PM +0000, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > 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 <dgilb...@redhat.com> > Reviewed-by: Peter Xu <pet...@redhat.com>
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