Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20210208a' into staging

Migration pull 2021-02-08

v2
  Dropped vmstate: Fix memory leak in vmstate_handle_alloc
    Broke on Power
  Added migration: only check page size match if RAM postcopy is enabled

# gpg: Signature made Mon 08 Feb 2021 11:28:14 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20210208a: (27 commits)
  migration: only check page size match if RAM postcopy is enabled
  migration: introduce snapshot-{save, load, delete} QMP commands
  iotests: fix loading of common.config from tests/ subdir
  iotests: add support for capturing and matching QMP events
  migration: introduce a delete_snapshot wrapper
  migration: wire up support for snapshot device selection
  migration: control whether snapshots are ovewritten
  block: rename and alter bdrv_all_find_snapshot semantics
  block: allow specifying name of block device for vmstate storage
  block: add ability to specify list of blockdevs during snapshot
  migration: stop returning errno from load_snapshot()
  migration: Make save_snapshot() return bool, not 0/-1
  block: push error reporting into bdrv_all_*_snapshot functions
  migration: Display the migration blockers
  migration: Add blocker information
  migration: Fix a few absurdly defective error messages
  migration: Fix cache_init()'s "Failed to allocate" error messages
  migration: Clean up signed vs. unsigned XBZRLE cache-size
  migration: Fix migrate-set-parameters argument validation
  migration: introduce 'userfaultfd-wrlat.py' script
  ...

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

2 files changed, 188 insertions, 75 deletions

diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index afd75ab628..75d7fa9510 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -900,10 +900,11 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
 
     ImageEntry *image_entry, *next_ie;
     SnapshotEntry *snapshot_entry;
+    Error *err = NULL;
 
-    bs = bdrv_all_find_vmstate_bs();
+    bs = bdrv_all_find_vmstate_bs(NULL, false, NULL, &err);
     if (!bs) {
-        monitor_printf(mon, "No available block device supports snapshots\n");
+        error_report_err(err);
         return;
     }
     aio_context = bdrv_get_aio_context(bs);
@@ -953,7 +954,7 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
     total = 0;
     for (i = 0; i < nb_sns; i++) {
         SnapshotEntry *next_sn;
-        if (bdrv_all_find_snapshot(sn_tab[i].name, &bs1) == 0) {
+        if (bdrv_all_has_snapshot(sn_tab[i].name, false, NULL, NULL) == 1) {
             global_snapshots[total] = i;
             total++;
             QTAILQ_FOREACH(image_entry, &image_list, next) {
diff --git a/block/snapshot.c b/block/snapshot.c
index a2bf3a54eb..e8ae9a28c1 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -447,6 +447,41 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
     return ret;
 }
 
+
+static int bdrv_all_get_snapshot_devices(bool has_devices, strList *devices,
+                                         GList **all_bdrvs,
+                                         Error **errp)
+{
+    g_autoptr(GList) bdrvs = NULL;
+
+    if (has_devices) {
+        if (!devices) {
+            error_setg(errp, "At least one device is required for snapshot");
+            return -1;
+        }
+
+        while (devices) {
+            BlockDriverState *bs = bdrv_find_node(devices->value);
+            if (!bs) {
+                error_setg(errp, "No block device node '%s'", devices->value);
+                return -1;
+            }
+            bdrvs = g_list_append(bdrvs, bs);
+            devices = devices->next;
+        }
+    } else {
+        BlockDriverState *bs;
+        BdrvNextIterator it;
+        for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+            bdrvs = g_list_append(bdrvs, bs);
+        }
+    }
+
+    *all_bdrvs = g_steal_pointer(&bdrvs);
+    return 0;
+}
+
+
 static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
 {
     if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
@@ -462,44 +497,59 @@ static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
  * These functions will properly handle dataplane (take aio_context_acquire
  * when appropriate for appropriate block drivers) */
 
-bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
+bool bdrv_all_can_snapshot(bool has_devices, strList *devices,
+                           Error **errp)
 {
-    bool ok = true;
-    BlockDriverState *bs;
-    BdrvNextIterator it;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
+
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return false;
+    }
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
+        bool ok = true;
 
         aio_context_acquire(ctx);
-        if (bdrv_all_snapshots_includes_bs(bs)) {
+        if (devices || bdrv_all_snapshots_includes_bs(bs)) {
             ok = bdrv_can_snapshot(bs);
         }
         aio_context_release(ctx);
         if (!ok) {
-            bdrv_next_cleanup(&it);
-            goto fail;
+            error_setg(errp, "Device '%s' is writable but does not support "
+                       "snapshots", bdrv_get_device_or_node_name(bs));
+            return false;
         }
+
+        iterbdrvs = iterbdrvs->next;
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ok;
+    return true;
 }
 
-int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
+int bdrv_all_delete_snapshot(const char *name,
+                             bool has_devices, strList *devices,
                              Error **errp)
 {
-    int ret = 0;
-    BlockDriverState *bs;
-    BdrvNextIterator it;
-    QEMUSnapshotInfo sn1, *snapshot = &sn1;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
+
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return -1;
+    }
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
+        QEMUSnapshotInfo sn1, *snapshot = &sn1;
+        int ret = 0;
 
         aio_context_acquire(ctx);
-        if (bdrv_all_snapshots_includes_bs(bs) &&
+        if ((devices || bdrv_all_snapshots_includes_bs(bs)) &&
             bdrv_snapshot_find(bs, snapshot, name) >= 0)
         {
             ret = bdrv_snapshot_delete(bs, snapshot->id_str,
@@ -507,118 +557,180 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
         }
         aio_context_release(ctx);
         if (ret < 0) {
-            bdrv_next_cleanup(&it);
-            goto fail;
+            error_prepend(errp, "Could not delete snapshot '%s' on '%s': ",
+                          name, bdrv_get_device_or_node_name(bs));
+            return -1;
         }
+
+        iterbdrvs = iterbdrvs->next;
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ret;
+    return 0;
 }
 
 
-int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
+int bdrv_all_goto_snapshot(const char *name,
+                           bool has_devices, strList *devices,
                            Error **errp)
 {
-    int ret = 0;
-    BlockDriverState *bs;
-    BdrvNextIterator it;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return -1;
+    }
+
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
-        if (bdrv_all_snapshots_includes_bs(bs)) {
+        if (devices || bdrv_all_snapshots_includes_bs(bs)) {
             ret = bdrv_snapshot_goto(bs, name, errp);
         }
         aio_context_release(ctx);
         if (ret < 0) {
-            bdrv_next_cleanup(&it);
-            goto fail;
+            error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
+                          name, bdrv_get_device_or_node_name(bs));
+            return -1;
         }
+
+        iterbdrvs = iterbdrvs->next;
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ret;
+    return 0;
 }
 
-int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
+int bdrv_all_has_snapshot(const char *name,
+                          bool has_devices, strList *devices,
+                          Error **errp)
 {
-    QEMUSnapshotInfo sn;
-    int err = 0;
-    BlockDriverState *bs;
-    BdrvNextIterator it;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return -1;
+    }
+
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
+        QEMUSnapshotInfo sn;
+        int ret = 0;
 
         aio_context_acquire(ctx);
-        if (bdrv_all_snapshots_includes_bs(bs)) {
-            err = bdrv_snapshot_find(bs, &sn, name);
+        if (devices || bdrv_all_snapshots_includes_bs(bs)) {
+            ret = bdrv_snapshot_find(bs, &sn, name);
         }
         aio_context_release(ctx);
-        if (err < 0) {
-            bdrv_next_cleanup(&it);
-            goto fail;
+        if (ret < 0) {
+            if (ret == -ENOENT) {
+                return 0;
+            } else {
+                error_setg_errno(errp, errno,
+                                 "Could not check snapshot '%s' on '%s'",
+                                 name, bdrv_get_device_or_node_name(bs));
+                return -1;
+            }
         }
+
+        iterbdrvs = iterbdrvs->next;
     }
 
-fail:
-    *first_bad_bs = bs;
-    return err;
+    return 1;
 }
 
 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
                              BlockDriverState *vm_state_bs,
                              uint64_t vm_state_size,
-                             BlockDriverState **first_bad_bs)
+                             bool has_devices, strList *devices,
+                             Error **errp)
 {
-    int err = 0;
-    BlockDriverState *bs;
-    BdrvNextIterator it;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
+
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return -1;
+    }
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
         if (bs == vm_state_bs) {
             sn->vm_state_size = vm_state_size;
-            err = bdrv_snapshot_create(bs, sn);
-        } else if (bdrv_all_snapshots_includes_bs(bs)) {
+            ret = bdrv_snapshot_create(bs, sn);
+        } else if (devices || bdrv_all_snapshots_includes_bs(bs)) {
             sn->vm_state_size = 0;
-            err = bdrv_snapshot_create(bs, sn);
+            ret = bdrv_snapshot_create(bs, sn);
         }
         aio_context_release(ctx);
-        if (err < 0) {
-            bdrv_next_cleanup(&it);
-            goto fail;
+        if (ret < 0) {
+            error_setg(errp, "Could not create snapshot '%s' on '%s'",
+                       sn->name, bdrv_get_device_or_node_name(bs));
+            return -1;
         }
+
+        iterbdrvs = iterbdrvs->next;
     }
 
-fail:
-    *first_bad_bs = bs;
-    return err;
+    return 0;
 }
 
-BlockDriverState *bdrv_all_find_vmstate_bs(void)
+
+BlockDriverState *bdrv_all_find_vmstate_bs(const char *vmstate_bs,
+                                           bool has_devices, strList *devices,
+                                           Error **errp)
 {
-    BlockDriverState *bs;
-    BdrvNextIterator it;
+    g_autoptr(GList) bdrvs = NULL;
+    GList *iterbdrvs;
+
+    if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
+        return NULL;
+    }
 
-    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+    iterbdrvs = bdrvs;
+    while (iterbdrvs) {
+        BlockDriverState *bs = iterbdrvs->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
-        bool found;
+        bool found = false;
 
         aio_context_acquire(ctx);
-        found = bdrv_all_snapshots_includes_bs(bs) && bdrv_can_snapshot(bs);
+        found = (devices || bdrv_all_snapshots_includes_bs(bs)) &&
+            bdrv_can_snapshot(bs);
         aio_context_release(ctx);
 
-        if (found) {
-            bdrv_next_cleanup(&it);
-            break;
+        if (vmstate_bs) {
+            if (g_str_equal(vmstate_bs,
+                            bdrv_get_node_name(bs))) {
+                if (found) {
+                    return bs;
+                } else {
+                    error_setg(errp,
+                               "vmstate block device '%s' does not support snapshots",
+                               vmstate_bs);
+                    return NULL;
+                }
+            }
+        } else if (found) {
+            return bs;
         }
+
+        iterbdrvs = iterbdrvs->next;
+    }
+
+    if (vmstate_bs) {
+        error_setg(errp,
+                   "vmstate block device '%s' does not exist", vmstate_bs);
+    } else {
+        error_setg(errp,
+                   "no block device can store vmstate for snapshot");
     }
-    return bs;
+    return NULL;
 }