diff mbox

[PULL,4/5] savevm: fail if migration blockers are present

Message ID 24f3902b088cd4f2dbebfd90527b5d81d6a050e9.1464023816.git.amit.shah@redhat.com
State New
Headers show

Commit Message

Amit Shah May 23, 2016, 5:19 p.m. UTC 
From: Greg Kurz <gkurz@linux.vnet.ibm.com>

QEMU has currently two ways to prevent migration to occur:
- migration blocker when it depends on runtime state
- VMStateDescription.unmigratable when migration is not supported at all

This patch gathers all the logic into a single function to be called from
both the savevm and the migrate paths.

This fixes a bug with 9p, at least, where savevm would succeed and the
following would happen in the guest after loadvm:

$ ls /host
ls: cannot access /host: Protocol error

With this patch:

(qemu) savevm foo
Migration is disabled when VirtFS export path '/' is mounted in the guest
using mount_tag 'host'

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <146239057139.11271.9011797645454781543.stgit@bahia.huguette.org>

[Update subject according to Paolo's suggestion - Amit]

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 include/migration/migration.h |  1 +
 migration/migration.c         | 21 +++++++++++++++------
 migration/savevm.c            |  2 +-
 3 files changed, 17 insertions(+), 7 deletions(-)

Comments

Greg Kurz May 26, 2016, 9:46 a.m. UTC | #1 
On Mon, 23 May 2016 22:49:46 +0530
Amit Shah <amit.shah@redhat.com> wrote:

> From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> 
> QEMU has currently two ways to prevent migration to occur:
> - migration blocker when it depends on runtime state
> - VMStateDescription.unmigratable when migration is not supported at all
> 
> This patch gathers all the logic into a single function to be called from
> both the savevm and the migrate paths.
> 
> This fixes a bug with 9p, at least, where savevm would succeed and the
> following would happen in the guest after loadvm:
> 
> $ ls /host
> ls: cannot access /host: Protocol error
> 
> With this patch:
> 
> (qemu) savevm foo
> Migration is disabled when VirtFS export path '/' is mounted in the guest
> using mount_tag 'host'
> 
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Message-Id: <146239057139.11271.9011797645454781543.stgit@bahia.huguette.org>
> 
> [Update subject according to Paolo's suggestion - Amit]
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---

FWIW this patch also fixes the issue in QEMU 2.5.

>  include/migration/migration.h |  1 +
>  migration/migration.c         | 21 +++++++++++++++------rtl8139
>  migration/savevm.c            |  2 +-
>  3 files changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index ac2c12c..9e36a97 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -210,6 +210,7 @@ int migrate_fd_close(MigrationState *s);
>  void add_migration_state_change_notifier(Notifier *notify);
>  void remove_migration_state_change_notifier(Notifier *notify);
>  MigrationState *migrate_init(const MigrationParams *params);
> +bool migration_is_blocked(Error **errp);
>  bool migration_in_setup(MigrationState *);
>  bool migration_has_finished(MigrationState *);
>  bool migration_has_failed(MigrationState *);
> diff --git a/migration/migration.c b/migration/migration.c
> index 12dbf5b..721d010 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -992,6 +992,20 @@ void qmp_migrate_incoming(const char *uri, Error **errp)
>      once = false;
>  }
> 
> +bool migration_is_blocked(Error **errp)
> +{
> +    if (qemu_savevm_state_blocked(errp)) {
> +        return true;
> +    }
> +
> +    if (migration_blockers) {
> +        *errp = error_copy(migration_blockers->data);
> +        return true;
> +    }
> +
> +    return false;
> +}
> +
>  void qmp_migrate(const char *uri, bool has_blk, bool blk,
>                   bool has_inc, bool inc, bool has_detach, bool detach,
>                   Error **errp)
> @@ -1014,12 +1028,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
>          return;
>      }
> 
> -    if (qemu_savevm_state_blocked(errp)) {
> -        return;
> -    }
> -
> -    if (migration_blockers) {
> -        *errp = error_copy(migration_blockers->data);
> +    if (migration_is_blocked(errp)) {
>          return;
>      }
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 8546fdf..f8450fd 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1170,7 +1170,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
>      MigrationState *ms = migrate_init(&params);
>      ms->to_dst_file = f;
> 
> -    if (qemu_savevm_state_blocked(errp)) {
> +    if (migration_is_blocked(errp)) {
>          return -EINVAL;
>      }
>
diff mbox

Patch

diff --git a/include/migration/migration.h b/include/migration/migration.h
index ac2c12c..9e36a97 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -210,6 +210,7 @@  int migrate_fd_close(MigrationState *s);
 void add_migration_state_change_notifier(Notifier *notify);
 void remove_migration_state_change_notifier(Notifier *notify);
 MigrationState *migrate_init(const MigrationParams *params);
+bool migration_is_blocked(Error **errp);
 bool migration_in_setup(MigrationState *);
 bool migration_has_finished(MigrationState *);
 bool migration_has_failed(MigrationState *);
diff --git a/migration/migration.c b/migration/migration.c
index 12dbf5b..721d010 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -992,6 +992,20 @@  void qmp_migrate_incoming(const char *uri, Error **errp)
     once = false;
 }
 
+bool migration_is_blocked(Error **errp)
+{
+    if (qemu_savevm_state_blocked(errp)) {
+        return true;
+    }
+
+    if (migration_blockers) {
+        *errp = error_copy(migration_blockers->data);
+        return true;
+    }
+
+    return false;
+}
+
 void qmp_migrate(const char *uri, bool has_blk, bool blk,
                  bool has_inc, bool inc, bool has_detach, bool detach,
                  Error **errp)
@@ -1014,12 +1028,7 @@  void qmp_migrate(const char *uri, bool has_blk, bool blk,
         return;
     }
 
-    if (qemu_savevm_state_blocked(errp)) {
-        return;
-    }
-
-    if (migration_blockers) {
-        *errp = error_copy(migration_blockers->data);
+    if (migration_is_blocked(errp)) {
         return;
     }
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 8546fdf..f8450fd 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1170,7 +1170,7 @@  static int qemu_savevm_state(QEMUFile *f, Error **errp)
     MigrationState *ms = migrate_init(&params);
     ms->to_dst_file = f;
 
-    if (qemu_savevm_state_blocked(errp)) {
+    if (migration_is_blocked(errp)) {
         return -EINVAL;
     }