Block pull request

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Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Block pull request

# gpg: Signature made Mon 23 Jun 2014 09:53:49 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/block-pull-request:
  block: asynchronously stop the VM on I/O errors
  vl: allow other threads to do qemu_system_vmstop_request
  sheepdog: fix NULL dereference in sd_create
  QemuOpts: check NULL opts in qemu_opt_get functions
  block: m25p80: Support read only bdrvs.
  block: m25p80: sync_page(): Deindent function body.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block.c

@@ -3626,10 +3626,27 @@ void bdrv_error_action(BlockDriverState *bs, BlockErrorAction action,
                        bool is_read, int error)
 {
     assert(error >= 0);
-    bdrv_emit_qmp_error_event(bs, QEVENT_BLOCK_IO_ERROR, action, is_read);
+
     if (action == BDRV_ACTION_STOP) {
-        vm_stop(RUN_STATE_IO_ERROR);
+        /* First set the iostatus, so that "info block" returns an iostatus
+         * that matches the events raised so far (an additional error iostatus
+         * is fine, but not a lost one).
+         */
         bdrv_iostatus_set_err(bs, error);
+
+        /* Then raise the request to stop the VM and the event.
+         * qemu_system_vmstop_request_prepare has two effects.  First,
+         * it ensures that the STOP event always comes after the
+         * BLOCK_IO_ERROR event.  Second, it ensures that even if management
+         * can observe the STOP event and do a "cont" before the STOP
+         * event is issued, the VM will not stop.  In this case, vm_start()
+         * also ensures that the STOP/RESUME pair of events is emitted.
+         */
+        qemu_system_vmstop_request_prepare();
+        bdrv_emit_qmp_error_event(bs, QEVENT_BLOCK_IO_ERROR, action, is_read);
+        qemu_system_vmstop_request(RUN_STATE_IO_ERROR);
+    } else {
+        bdrv_emit_qmp_error_event(bs, QEVENT_BLOCK_IO_ERROR, action, is_read);
     }
 }
 

block/sheepdog.c

@@ -1756,6 +1756,7 @@ static int sd_create(const char *filename, QemuOpts *opts,
         bdrv_unref(bs);
     }
 
+    s->aio_context = qemu_get_aio_context();
     ret = do_sd_create(s, &vid, 0, errp);
     if (ret) {
         goto out;

cpus.c

@@ -1206,6 +1206,7 @@ void cpu_stop_current(void)
 int vm_stop(RunState state)
 {
     if (qemu_in_vcpu_thread()) {
+        qemu_system_vmstop_request_prepare();
         qemu_system_vmstop_request(state);
         /*
          * FIXME: should not return to device code in case

docs/qmp/qmp-events.txt

@@ -62,7 +62,7 @@ Data:
 - "action": action that has been taken, it's one of the following (json-string):
     "ignore": error has been ignored
     "report": error has been reported to the device
-    "stop": error caused VM to be stopped
+    "stop": the VM is going to stop because of the error
 
 Example:
 

hw/block/m25p80.c

@@ -288,18 +288,20 @@ static void bdrv_sync_complete(void *opaque, int ret)
 
 static void flash_sync_page(Flash *s, int page)
 {
-    if (s->bdrv) {
-        int bdrv_sector, nb_sectors;
-        QEMUIOVector iov;
+    int bdrv_sector, nb_sectors;
+    QEMUIOVector iov;
 
-        bdrv_sector = (page * s->pi->page_size) / BDRV_SECTOR_SIZE;
-        nb_sectors = DIV_ROUND_UP(s->pi->page_size, BDRV_SECTOR_SIZE);
-        qemu_iovec_init(&iov, 1);
-        qemu_iovec_add(&iov, s->storage + bdrv_sector * BDRV_SECTOR_SIZE,
-                                                nb_sectors * BDRV_SECTOR_SIZE);
-        bdrv_aio_writev(s->bdrv, bdrv_sector, &iov, nb_sectors,
-                                                bdrv_sync_complete, NULL);
+    if (!s->bdrv || bdrv_is_read_only(s->bdrv)) {
+        return;
     }
+
+    bdrv_sector = (page * s->pi->page_size) / BDRV_SECTOR_SIZE;
+    nb_sectors = DIV_ROUND_UP(s->pi->page_size, BDRV_SECTOR_SIZE);
+    qemu_iovec_init(&iov, 1);
+    qemu_iovec_add(&iov, s->storage + bdrv_sector * BDRV_SECTOR_SIZE,
+                   nb_sectors * BDRV_SECTOR_SIZE);
+    bdrv_aio_writev(s->bdrv, bdrv_sector, &iov, nb_sectors, bdrv_sync_complete,
+                    NULL);
 }
 
 static inline void flash_sync_area(Flash *s, int64_t off, int64_t len)
@@ -307,7 +309,7 @@ static inline void flash_sync_area(Flash *s, int64_t off, int64_t len)
     int64_t start, end, nb_sectors;
     QEMUIOVector iov;
 
-    if (!s->bdrv) {
+    if (!s->bdrv || bdrv_is_read_only(s->bdrv)) {
         return;
     }
 
@@ -625,10 +627,6 @@ static int m25p80_init(SSISlave *ss)
     if (dinfo && dinfo->bdrv) {
         DB_PRINT_L(0, "Binding to IF_MTD drive\n");
         s->bdrv = dinfo->bdrv;
-        if (bdrv_is_read_only(s->bdrv)) {
-            fprintf(stderr, "Can't use a read-only drive");
-            return 1;
-        }
 
         /* FIXME: Move to late init */
         if (bdrv_read(s->bdrv, 0, s->storage, DIV_ROUND_UP(s->size,

include/sysemu/sysemu.h

@@ -62,6 +62,7 @@ void qemu_system_powerdown_request(void);
 void qemu_register_powerdown_notifier(Notifier *notifier);
 void qemu_system_debug_request(void);
 void qemu_system_vmstop_request(RunState reason);
+void qemu_system_vmstop_request_prepare(void);
 int qemu_shutdown_requested_get(void);
 int qemu_reset_requested_get(void);
 void qemu_system_killed(int signal, pid_t pid);

stubs/vm-stop.c

@@ -1,7 +1,12 @@
 #include "qemu-common.h"
 #include "sysemu/sysemu.h"
 
-int vm_stop(RunState state)
+void qemu_system_vmstop_request_prepare(void)
+{
+    abort();
+}
+
+void qemu_system_vmstop_request(RunState state)
 {
     abort();
 }

target-lm32/op_helper.c

@@ -42,7 +42,7 @@ void HELPER(ill)(CPULM32State *env)
     fprintf(stderr, "VM paused due to illegal instruction. "
             "Connect a debugger or switch to the monitor console "
             "to find out more.\n");
-    qemu_system_vmstop_request(RUN_STATE_PAUSED);
+    vm_stop(RUN_STATE_PAUSED);
     cs->halted = 1;
     raise_exception(env, EXCP_HALTED);
 #endif

util/qemu-option.c

@@ -310,8 +310,13 @@ static void qemu_opt_del_all(QemuOpts *opts, const char *name)
 
 const char *qemu_opt_get(QemuOpts *opts, const char *name)
 {
-    QemuOpt *opt = qemu_opt_find(opts, name);
+    QemuOpt *opt;
 
+    if (opts == NULL) {
+        return NULL;
+    }
+
+    opt = qemu_opt_find(opts, name);
     if (!opt) {
         const QemuOptDesc *desc = find_desc_by_name(opts->list->desc, name);
         if (desc && desc->def_value_str) {
@@ -364,9 +369,14 @@ bool qemu_opt_has_help_opt(QemuOpts *opts)
 static bool qemu_opt_get_bool_helper(QemuOpts *opts, const char *name,
                                      bool defval, bool del)
 {
-    QemuOpt *opt = qemu_opt_find(opts, name);
+    QemuOpt *opt;
     bool ret = defval;
 
+    if (opts == NULL) {
+        return ret;
+    }
+
+    opt = qemu_opt_find(opts, name);
     if (opt == NULL) {
         const QemuOptDesc *desc = find_desc_by_name(opts->list->desc, name);
         if (desc && desc->def_value_str) {
@@ -395,9 +405,14 @@ bool qemu_opt_get_bool_del(QemuOpts *opts, const char *name, bool defval)
 static uint64_t qemu_opt_get_number_helper(QemuOpts *opts, const char *name,
                                            uint64_t defval, bool del)
 {
-    QemuOpt *opt = qemu_opt_find(opts, name);
+    QemuOpt *opt;
     uint64_t ret = defval;
 
+    if (opts == NULL) {
+        return ret;
+    }
+
+    opt = qemu_opt_find(opts, name);
     if (opt == NULL) {
         const QemuOptDesc *desc = find_desc_by_name(opts->list->desc, name);
         if (desc && desc->def_value_str) {
@@ -427,9 +442,14 @@ uint64_t qemu_opt_get_number_del(QemuOpts *opts, const char *name,
 static uint64_t qemu_opt_get_size_helper(QemuOpts *opts, const char *name,
                                          uint64_t defval, bool del)
 {
-    QemuOpt *opt = qemu_opt_find(opts, name);
+    QemuOpt *opt;
     uint64_t ret = defval;
 
+    if (opts == NULL) {
+        return ret;
+    }
+
+    opt = qemu_opt_find(opts, name);
     if (opt == NULL) {
         const QemuOptDesc *desc = find_desc_by_name(opts->list->desc, name);
         if (desc && desc->def_value_str) {

vl.c

@@ -574,6 +574,10 @@ static int default_driver_check(QemuOpts *opts, void *opaque)
 
 static RunState current_run_state = RUN_STATE_PRELAUNCH;
 
+/* We use RUN_STATE_MAX but any invalid value will do */
+static RunState vmstop_requested = RUN_STATE_MAX;
+static QemuMutex vmstop_lock;
+
 typedef struct {
     RunState from;
     RunState to;
@@ -650,10 +654,11 @@ static void runstate_init(void)
     const RunStateTransition *p;
 
     memset(&runstate_valid_transitions, 0, sizeof(runstate_valid_transitions));
-
     for (p = &runstate_transitions_def[0]; p->from != RUN_STATE_MAX; p++) {
         runstate_valid_transitions[p->from][p->to] = true;
     }
+
+    qemu_mutex_init(&vmstop_lock);
 }
 
 /* This function will abort() on invalid state transitions */
@@ -693,6 +698,54 @@ StatusInfo *qmp_query_status(Error **errp)
     return info;
 }
 
+static bool qemu_vmstop_requested(RunState *r)
+{
+    qemu_mutex_lock(&vmstop_lock);
+    *r = vmstop_requested;
+    vmstop_requested = RUN_STATE_MAX;
+    qemu_mutex_unlock(&vmstop_lock);
+    return *r < RUN_STATE_MAX;
+}
+
+void qemu_system_vmstop_request_prepare(void)
+{
+    qemu_mutex_lock(&vmstop_lock);
+}
+
+void qemu_system_vmstop_request(RunState state)
+{
+    vmstop_requested = state;
+    qemu_mutex_unlock(&vmstop_lock);
+    qemu_notify_event();
+}
+
+void vm_start(void)
+{
+    RunState requested;
+
+    qemu_vmstop_requested(&requested);
+    if (runstate_is_running() && requested == RUN_STATE_MAX) {
+        return;
+    }
+
+    /* Ensure that a STOP/RESUME pair of events is emitted if a
+     * vmstop request was pending.  The BLOCK_IO_ERROR event, for
+     * example, according to documentation is always followed by
+     * the STOP event.
+     */
+    if (runstate_is_running()) {
+        monitor_protocol_event(QEVENT_STOP, NULL);
+    } else {
+        cpu_enable_ticks();
+        runstate_set(RUN_STATE_RUNNING);
+        vm_state_notify(1, RUN_STATE_RUNNING);
+        resume_all_vcpus();
+    }
+
+    monitor_protocol_event(QEVENT_RESUME, NULL);
+}
+
+
 /***********************************************************/
 /* real time host monotonic timer */
 
@@ -1658,17 +1711,6 @@ void vm_state_notify(int running, RunState state)
     }
 }
 
-void vm_start(void)
-{
-    if (!runstate_is_running()) {
-        cpu_enable_ticks();
-        runstate_set(RUN_STATE_RUNNING);
-        vm_state_notify(1, RUN_STATE_RUNNING);
-        resume_all_vcpus();
-        monitor_protocol_event(QEVENT_RESUME, NULL);
-    }
-}
-
 /* reset/shutdown handler */
 
 typedef struct QEMUResetEntry {
@@ -1693,7 +1735,6 @@ static NotifierList suspend_notifiers =
 static NotifierList wakeup_notifiers =
     NOTIFIER_LIST_INITIALIZER(wakeup_notifiers);
 static uint32_t wakeup_reason_mask = ~(1 << QEMU_WAKEUP_REASON_NONE);
-static RunState vmstop_requested = RUN_STATE_MAX;
 
 int qemu_shutdown_requested_get(void)
 {
@@ -1761,18 +1802,6 @@ static int qemu_debug_requested(void)
     return r;
 }
 
-/* We use RUN_STATE_MAX but any invalid value will do */
-static bool qemu_vmstop_requested(RunState *r)
-{
-    if (vmstop_requested < RUN_STATE_MAX) {
-        *r = vmstop_requested;
-        vmstop_requested = RUN_STATE_MAX;
-        return true;
-    }
-
-    return false;
-}
-
 void qemu_register_reset(QEMUResetHandler *func, void *opaque)
 {
     QEMUResetEntry *re = g_malloc0(sizeof(QEMUResetEntry));
@@ -1922,12 +1951,6 @@ void qemu_system_debug_request(void)
     qemu_notify_event();
 }
 
-void qemu_system_vmstop_request(RunState state)
-{
-    vmstop_requested = state;
-    qemu_notify_event();
-}
-
 static bool main_loop_should_exit(void)
 {
     RunState r;