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 <dgilbert@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert
Michael S. Tsirkin
parent
2a84ffc0be
commit
00fa4fc85b
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@ -155,6 +155,8 @@ MigrationIncomingState *migration_incoming_get_current(void)
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if (!once) {
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mis_current.state = MIGRATION_STATUS_NONE;
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memset(&mis_current, 0, sizeof(MigrationIncomingState));
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mis_current.postcopy_remote_fds = g_array_new(FALSE, TRUE,
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sizeof(struct PostCopyFD));
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qemu_mutex_init(&mis_current.rp_mutex);
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qemu_event_init(&mis_current.main_thread_load_event, false);
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once = true;
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@ -177,6 +179,10 @@ void migration_incoming_state_destroy(void)
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qemu_fclose(mis->from_src_file);
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mis->from_src_file = NULL;
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}
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if (mis->postcopy_remote_fds) {
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g_array_free(mis->postcopy_remote_fds, TRUE);
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mis->postcopy_remote_fds = NULL;
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}
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qemu_event_reset(&mis->main_thread_load_event);
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}
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@ -51,6 +51,8 @@ struct MigrationIncomingState {
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QemuMutex rp_mutex; /* We send replies from multiple threads */
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void *postcopy_tmp_page;
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void *postcopy_tmp_zero_page;
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/* PostCopyFD's for external userfaultfds & handlers of shared memory */
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GArray *postcopy_remote_fds;
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QEMUBH *bh;
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@ -533,29 +533,44 @@ static void *postcopy_ram_fault_thread(void *opaque)
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MigrationIncomingState *mis = opaque;
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struct uffd_msg msg;
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int ret;
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size_t index;
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RAMBlock *rb = NULL;
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RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */
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trace_postcopy_ram_fault_thread_entry();
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qemu_sem_post(&mis->fault_thread_sem);
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struct pollfd *pfd;
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size_t pfd_len = 2 + mis->postcopy_remote_fds->len;
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pfd = g_new0(struct pollfd, pfd_len);
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pfd[0].fd = mis->userfault_fd;
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pfd[0].events = POLLIN;
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pfd[1].fd = mis->userfault_event_fd;
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pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
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trace_postcopy_ram_fault_thread_fds_core(pfd[0].fd, pfd[1].fd);
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for (index = 0; index < mis->postcopy_remote_fds->len; index++) {
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struct PostCopyFD *pcfd = &g_array_index(mis->postcopy_remote_fds,
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struct PostCopyFD, index);
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pfd[2 + index].fd = pcfd->fd;
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pfd[2 + index].events = POLLIN;
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trace_postcopy_ram_fault_thread_fds_extra(2 + index, pcfd->idstr,
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pcfd->fd);
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}
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while (true) {
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ram_addr_t rb_offset;
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struct pollfd pfd[2];
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int poll_result;
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/*
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* We're mainly waiting for the kernel to give us a faulting HVA,
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* however we can be told to quit via userfault_quit_fd which is
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* an eventfd
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*/
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pfd[0].fd = mis->userfault_fd;
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pfd[0].events = POLLIN;
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pfd[0].revents = 0;
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pfd[1].fd = mis->userfault_event_fd;
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pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
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pfd[1].revents = 0;
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if (poll(pfd, 2, -1 /* Wait forever */) == -1) {
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poll_result = poll(pfd, pfd_len, -1 /* Wait forever */);
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if (poll_result == -1) {
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error_report("%s: userfault poll: %s", __func__, strerror(errno));
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break;
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}
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@ -575,57 +590,117 @@ static void *postcopy_ram_fault_thread(void *opaque)
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}
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}
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ret = read(mis->userfault_fd, &msg, sizeof(msg));
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if (ret != sizeof(msg)) {
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if (errno == EAGAIN) {
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/*
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* if a wake up happens on the other thread just after
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* the poll, there is nothing to read.
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*/
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continue;
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if (pfd[0].revents) {
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poll_result--;
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ret = read(mis->userfault_fd, &msg, sizeof(msg));
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if (ret != sizeof(msg)) {
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if (errno == EAGAIN) {
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/*
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* if a wake up happens on the other thread just after
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* the poll, there is nothing to read.
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*/
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continue;
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}
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if (ret < 0) {
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error_report("%s: Failed to read full userfault "
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"message: %s",
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__func__, strerror(errno));
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break;
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} else {
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error_report("%s: Read %d bytes from userfaultfd "
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"expected %zd",
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__func__, ret, sizeof(msg));
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break; /* Lost alignment, don't know what we'd read next */
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}
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}
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if (ret < 0) {
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error_report("%s: Failed to read full userfault message: %s",
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__func__, strerror(errno));
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if (msg.event != UFFD_EVENT_PAGEFAULT) {
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error_report("%s: Read unexpected event %ud from userfaultfd",
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__func__, msg.event);
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continue; /* It's not a page fault, shouldn't happen */
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}
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rb = qemu_ram_block_from_host(
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(void *)(uintptr_t)msg.arg.pagefault.address,
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true, &rb_offset);
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if (!rb) {
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error_report("postcopy_ram_fault_thread: Fault outside guest: %"
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PRIx64, (uint64_t)msg.arg.pagefault.address);
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break;
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} else {
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error_report("%s: Read %d bytes from userfaultfd expected %zd",
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__func__, ret, sizeof(msg));
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break; /* Lost alignment, don't know what we'd read next */
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}
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}
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if (msg.event != UFFD_EVENT_PAGEFAULT) {
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error_report("%s: Read unexpected event %ud from userfaultfd",
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__func__, msg.event);
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continue; /* It's not a page fault, shouldn't happen */
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}
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rb = qemu_ram_block_from_host(
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(void *)(uintptr_t)msg.arg.pagefault.address,
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true, &rb_offset);
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if (!rb) {
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error_report("postcopy_ram_fault_thread: Fault outside guest: %"
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PRIx64, (uint64_t)msg.arg.pagefault.address);
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break;
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}
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rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
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trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
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rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
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trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
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qemu_ram_get_idstr(rb),
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rb_offset);
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/*
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* Send the request to the source - we want to request one
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* of our host page sizes (which is >= TPS)
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*/
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if (rb != last_rb) {
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last_rb = rb;
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migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
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rb_offset, qemu_ram_pagesize(rb));
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} else {
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/* Save some space */
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migrate_send_rp_req_pages(mis, NULL,
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rb_offset, qemu_ram_pagesize(rb));
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}
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}
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/*
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* Send the request to the source - we want to request one
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* of our host page sizes (which is >= TPS)
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*/
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if (rb != last_rb) {
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last_rb = rb;
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migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
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rb_offset, qemu_ram_pagesize(rb));
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} else {
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/* Save some space */
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migrate_send_rp_req_pages(mis, NULL,
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rb_offset, qemu_ram_pagesize(rb));
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/* Now handle any requests from external processes on shared memory */
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/* TODO: May need to handle devices deregistering during postcopy */
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for (index = 2; index < pfd_len && poll_result; index++) {
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if (pfd[index].revents) {
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struct PostCopyFD *pcfd =
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&g_array_index(mis->postcopy_remote_fds,
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struct PostCopyFD, index - 2);
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poll_result--;
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if (pfd[index].revents & POLLERR) {
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error_report("%s: POLLERR on poll %zd fd=%d",
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__func__, index, pcfd->fd);
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pfd[index].events = 0;
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continue;
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}
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ret = read(pcfd->fd, &msg, sizeof(msg));
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if (ret != sizeof(msg)) {
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if (errno == EAGAIN) {
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/*
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* if a wake up happens on the other thread just after
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* the poll, there is nothing to read.
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*/
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continue;
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}
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if (ret < 0) {
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error_report("%s: Failed to read full userfault "
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"message: %s (shared) revents=%d",
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__func__, strerror(errno),
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pfd[index].revents);
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/*TODO: Could just disable this sharer */
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break;
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} else {
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error_report("%s: Read %d bytes from userfaultfd "
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"expected %zd (shared)",
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__func__, ret, sizeof(msg));
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/*TODO: Could just disable this sharer */
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break; /*Lost alignment,don't know what we'd read next*/
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}
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}
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if (msg.event != UFFD_EVENT_PAGEFAULT) {
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error_report("%s: Read unexpected event %ud "
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"from userfaultfd (shared)",
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__func__, msg.event);
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continue; /* It's not a page fault, shouldn't happen */
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}
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/* Call the device handler registered with us */
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ret = pcfd->handler(pcfd, &msg);
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if (ret) {
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error_report("%s: Failed to resolve shared fault on %zd/%s",
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__func__, index, pcfd->idstr);
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/* TODO: Fail? Disable this sharer? */
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}
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}
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}
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}
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trace_postcopy_ram_fault_thread_exit();
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@ -970,3 +1045,31 @@ PostcopyState postcopy_state_set(PostcopyState new_state)
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{
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return atomic_xchg(&incoming_postcopy_state, new_state);
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}
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/* Register a handler for external shared memory postcopy
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* called on the destination.
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*/
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void postcopy_register_shared_ufd(struct PostCopyFD *pcfd)
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{
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MigrationIncomingState *mis = migration_incoming_get_current();
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mis->postcopy_remote_fds = g_array_append_val(mis->postcopy_remote_fds,
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*pcfd);
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}
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/* Unregister a handler for external shared memory postcopy
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*/
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void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
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{
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guint i;
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MigrationIncomingState *mis = migration_incoming_get_current();
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GArray *pcrfds = mis->postcopy_remote_fds;
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for (i = 0; i < pcrfds->len; i++) {
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struct PostCopyFD *cur = &g_array_index(pcrfds, struct PostCopyFD, i);
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if (cur->fd == pcfd->fd) {
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mis->postcopy_remote_fds = g_array_remove_index(pcrfds, i);
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return;
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}
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}
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}
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@ -143,4 +143,25 @@ void postcopy_remove_notifier(NotifierWithReturn *n);
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/* Call the notifier list set by postcopy_add_start_notifier */
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int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
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struct PostCopyFD;
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/* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
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typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
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struct PostCopyFD {
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int fd;
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/* Data to pass to handler */
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void *data;
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/* Handler to be called whenever we get a poll event */
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pcfdhandler handler;
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/* A string to use in error messages */
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const char *idstr;
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};
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/* Register a userfaultfd owned by an external process for
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* shared memory.
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*/
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void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
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void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
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#endif
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@ -190,6 +190,8 @@ postcopy_place_page_zero(void *host_addr) "host=%p"
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postcopy_ram_enable_notify(void) ""
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postcopy_ram_fault_thread_entry(void) ""
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postcopy_ram_fault_thread_exit(void) ""
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postcopy_ram_fault_thread_fds_core(int baseufd, int quitfd) "ufd: %d quitfd: %d"
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postcopy_ram_fault_thread_fds_extra(size_t index, const char *name, int fd) "%zd/%s: %d"
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postcopy_ram_fault_thread_quit(void) ""
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postcopy_ram_fault_thread_request(uint64_t hostaddr, const char *ramblock, size_t offset) "Request for HVA=0x%" PRIx64 " rb=%s offset=0x%zx"
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postcopy_ram_incoming_cleanup_closeuf(void) ""
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