Migration Pull

[dropped fabiano's patch on modifying cpu model for arm migration tests for
  now]
 
 - Fabiano's patchset to fix migration state references in BHs
 - Fabiano's new 'n-1' migration test for CI
 - Het's fix on making "uri" optional in QMP migrate cmd
 - Markus's HMP leak fix reported by Coverity
 - Paolo's cleanup on uffd to replace u64 usage
 - Peter's small migration cleanup series all over the places
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Merge tag 'migration-20240126-pull-request' of https://gitlab.com/peterx/qemu into staging

Migration Pull

[dropped fabiano's patch on modifying cpu model for arm migration tests for
 now]

- Fabiano's patchset to fix migration state references in BHs
- Fabiano's new 'n-1' migration test for CI
- Het's fix on making "uri" optional in QMP migrate cmd
- Markus's HMP leak fix reported by Coverity
- Paolo's cleanup on uffd to replace u64 usage
- Peter's small migration cleanup series all over the places

# -----BEGIN PGP SIGNATURE-----
#
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# ZGhhdC5jb20ACgkQO1/MzfOr1wYHjgD9F2Fnrf4EuPNC/gF3yUvHVz1mgHqevb/g
# pw/ThcJF31wBALuWmwuUaNWm+VNtRc10YH6bY7HZW8oa1RefRN6QZn0L
# =JGTX
# -----END PGP SIGNATURE-----
# gpg: Signature made Mon 29 Jan 2024 03:03:20 GMT
# gpg:                using EDDSA key B9184DC20CC457DACF7DD1A93B5FCCCDF3ABD706
# gpg:                issuer "peterx@redhat.com"
# gpg: Good signature from "Peter Xu <xzpeter@gmail.com>" [marginal]
# gpg:                 aka "Peter Xu <peterx@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: B918 4DC2 0CC4 57DA CF7D  D1A9 3B5F CCCD F3AB D706

* tag 'migration-20240126-pull-request' of https://gitlab.com/peterx/qemu:
  Make 'uri' optional for migrate QAPI
  migration: Centralize BH creation and dispatch
  migration: Add a wrapper to qemu_bh_schedule
  migration: Reference migration state around loadvm_postcopy_handle_run_bh
  migration: Take reference to migration state around bg_migration_vm_start_bh
  migration: Fix use-after-free of migration state object
  migration/yank: Use channel features
  ci: Disable migration compatibility tests for aarch64
  ci: Add a migration compatibility test job
  analyze-migration.py: Remove trick on parsing ramblocks
  migration: Drop unnecessary check in ram's pending_exact()
  migration: Make threshold_size an uint64_t
  migration: Plug memory leak on HMP migrate error path
  userfaultfd: use 1ULL to build ioctl masks

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

.gitlab-ci.d/buildtest.yml

@@ -167,6 +167,70 @@ build-system-centos:
       x86_64-softmmu rx-softmmu sh4-softmmu nios2-softmmu
     MAKE_CHECK_ARGS: check-build
 
+# Previous QEMU release. Used for cross-version migration tests.
+build-previous-qemu:
+  extends: .native_build_job_template
+  artifacts:
+    when: on_success
+    expire_in: 2 days
+    paths:
+      - build-previous
+    exclude:
+      - build-previous/**/*.p
+      - build-previous/**/*.a.p
+      - build-previous/**/*.fa.p
+      - build-previous/**/*.c.o
+      - build-previous/**/*.c.o.d
+      - build-previous/**/*.fa
+  needs:
+    job: amd64-opensuse-leap-container
+  variables:
+    IMAGE: opensuse-leap
+    TARGETS: x86_64-softmmu aarch64-softmmu
+  before_script:
+    - export QEMU_PREV_VERSION="$(sed 's/\([0-9.]*\)\.[0-9]*/v\1.0/' VERSION)"
+    - git checkout $QEMU_PREV_VERSION
+  after_script:
+    - mv build build-previous
+
+.migration-compat-common:
+  extends: .common_test_job_template
+  needs:
+    - job: build-previous-qemu
+    - job: build-system-opensuse
+  # The old QEMU could have bugs unrelated to migration that are
+  # already fixed in the current development branch, so this test
+  # might fail.
+  allow_failure: true
+  variables:
+    IMAGE: opensuse-leap
+    MAKE_CHECK_ARGS: check-build
+  script:
+    # Use the migration-tests from the older QEMU tree. This avoids
+    # testing an old QEMU against new features/tests that it is not
+    # compatible with.
+    - cd build-previous
+    # old to new
+    - QTEST_QEMU_BINARY_SRC=./qemu-system-${TARGET}
+          QTEST_QEMU_BINARY=../build/qemu-system-${TARGET} ./tests/qtest/migration-test
+    # new to old
+    - QTEST_QEMU_BINARY_DST=./qemu-system-${TARGET}
+          QTEST_QEMU_BINARY=../build/qemu-system-${TARGET} ./tests/qtest/migration-test
+
+# This job is disabled until we release 9.0. The existing
+# migration-test in 8.2 is broken on aarch64. The fix was already
+# commited, but it will only take effect once 9.0 is out.
+migration-compat-aarch64:
+  extends: .migration-compat-common
+  variables:
+    TARGET: aarch64
+    QEMU_JOB_SKIPPED: 1
+
+migration-compat-x86_64:
+  extends: .migration-compat-common
+  variables:
+    TARGET: x86_64
+
 check-system-centos:
   extends: .native_test_job_template
   needs:

migration/migration-hmp-cmds.c

@@ -764,7 +764,7 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
     bool resume = qdict_get_try_bool(qdict, "resume", false);
     const char *uri = qdict_get_str(qdict, "uri");
     Error *err = NULL;
-    MigrationChannelList *caps = NULL;
+    g_autoptr(MigrationChannelList) caps = NULL;
     g_autoptr(MigrationChannel) channel = NULL;
 
     if (inc) {
@@ -789,8 +789,6 @@ void hmp_migrate(Monitor *mon, const QDict *qdict)
         return;
     }
 
-    qapi_free_MigrationChannelList(caps);
-
     if (!detach) {
         HMPMigrationStatus *status;
 

migration/migration.c

@@ -199,6 +199,47 @@ void migration_object_init(void)
     dirty_bitmap_mig_init();
 }
 
+typedef struct {
+    QEMUBH *bh;
+    QEMUBHFunc *cb;
+    void *opaque;
+} MigrationBH;
+
+static void migration_bh_dispatch_bh(void *opaque)
+{
+    MigrationState *s = migrate_get_current();
+    MigrationBH *migbh = opaque;
+
+    /* cleanup this BH */
+    qemu_bh_delete(migbh->bh);
+    migbh->bh = NULL;
+
+    /* dispatch the other one */
+    migbh->cb(migbh->opaque);
+    object_unref(OBJECT(s));
+
+    g_free(migbh);
+}
+
+void migration_bh_schedule(QEMUBHFunc *cb, void *opaque)
+{
+    MigrationState *s = migrate_get_current();
+    MigrationBH *migbh = g_new0(MigrationBH, 1);
+    QEMUBH *bh = qemu_bh_new(migration_bh_dispatch_bh, migbh);
+
+    /* Store these to dispatch when the BH runs */
+    migbh->bh = bh;
+    migbh->cb = cb;
+    migbh->opaque = opaque;
+
+    /*
+     * Ref the state for bh, because it may be called when
+     * there're already no other refs
+     */
+    object_ref(OBJECT(s));
+    qemu_bh_schedule(bh);
+}
+
 void migration_cancel(const Error *error)
 {
     if (error) {
@@ -646,7 +687,6 @@ static void process_incoming_migration_bh(void *opaque)
      */
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COMPLETED);
-    qemu_bh_delete(mis->bh);
     migration_incoming_state_destroy();
 }
 
@@ -712,8 +752,7 @@ process_incoming_migration_co(void *opaque)
         goto fail;
     }
 
-    mis->bh = qemu_bh_new(process_incoming_migration_bh, mis);
+    migration_bh_schedule(process_incoming_migration_bh, mis);
-    qemu_bh_schedule(mis->bh);
     return;
 fail:
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
@@ -1274,9 +1313,6 @@ void migrate_set_state(int *state, int old_state, int new_state)
 
 static void migrate_fd_cleanup(MigrationState *s)
 {
-    qemu_bh_delete(s->cleanup_bh);
-    s->cleanup_bh = NULL;
-
     g_free(s->hostname);
     s->hostname = NULL;
     json_writer_free(s->vmdesc);
@@ -1330,21 +1366,9 @@ static void migrate_fd_cleanup(MigrationState *s)
     yank_unregister_instance(MIGRATION_YANK_INSTANCE);
 }
 
-static void migrate_fd_cleanup_schedule(MigrationState *s)
-{
-    /*
-     * Ref the state for bh, because it may be called when
-     * there're already no other refs
-     */
-    object_ref(OBJECT(s));
-    qemu_bh_schedule(s->cleanup_bh);
-}
-
 static void migrate_fd_cleanup_bh(void *opaque)
 {
-    MigrationState *s = opaque;
+    migrate_fd_cleanup(opaque);
-    migrate_fd_cleanup(s);
-    object_unref(OBJECT(s));
 }
 
 void migrate_set_error(MigrationState *s, const Error *error)
@@ -1567,8 +1591,6 @@ int migrate_init(MigrationState *s, Error **errp)
      * parameters/capabilities that the user set, and
      * locks.
      */
-    s->cleanup_bh = 0;
-    s->vm_start_bh = 0;
     s->to_dst_file = NULL;
     s->state = MIGRATION_STATUS_NONE;
     s->rp_state.from_dst_file = NULL;
@@ -3138,7 +3160,8 @@ static void migration_iteration_finish(MigrationState *s)
         error_report("%s: Unknown ending state %d", __func__, s->state);
         break;
     }
-    migrate_fd_cleanup_schedule(s);
+
+    migration_bh_schedule(migrate_fd_cleanup_bh, s);
     bql_unlock();
 }
 
@@ -3169,7 +3192,7 @@ static void bg_migration_iteration_finish(MigrationState *s)
         break;
     }
 
-    migrate_fd_cleanup_schedule(s);
+    migration_bh_schedule(migrate_fd_cleanup_bh, s);
     bql_unlock();
 }
 
@@ -3375,9 +3398,6 @@ static void bg_migration_vm_start_bh(void *opaque)
 {
     MigrationState *s = opaque;
 
-    qemu_bh_delete(s->vm_start_bh);
-    s->vm_start_bh = NULL;
-
     vm_resume(s->vm_old_state);
     migration_downtime_end(s);
 }
@@ -3483,9 +3503,7 @@ static void *bg_migration_thread(void *opaque)
      * calling VM state change notifiers from vm_start() would initiate
      * writes to virtio VQs memory which is in write-protected region.
      */
-    s->vm_start_bh = qemu_bh_new(bg_migration_vm_start_bh, s);
+    migration_bh_schedule(bg_migration_vm_start_bh, s);
-    qemu_bh_schedule(s->vm_start_bh);
-
     bql_unlock();
 
     while (migration_is_active(s)) {
@@ -3541,12 +3559,6 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
     migrate_error_free(s);
 
     s->expected_downtime = migrate_downtime_limit();
-    if (resume) {
-        assert(s->cleanup_bh);
-    } else {
-        assert(!s->cleanup_bh);
-        s->cleanup_bh = qemu_bh_new(migrate_fd_cleanup_bh, s);
-    }
     if (error_in) {
         migrate_fd_error(s, error_in);
         if (resume) {

migration/migration.h

@@ -159,8 +159,6 @@ struct MigrationIncomingState {
     /* PostCopyFD's for external userfaultfds & handlers of shared memory */
     GArray   *postcopy_remote_fds;
 
-    QEMUBH *bh;
-
     int state;
 
     /*
@@ -255,8 +253,6 @@ struct MigrationState {
 
     /*< public >*/
     QemuThread thread;
-    QEMUBH *vm_start_bh;
-    QEMUBH *cleanup_bh;
     /* Protected by qemu_file_lock */
     QEMUFile *to_dst_file;
     /* Postcopy specific transfer channel */
@@ -296,7 +292,7 @@ struct MigrationState {
      * this threshold; it's calculated from the requested downtime and
      * measured bandwidth, or avail-switchover-bandwidth if specified.
      */
-    int64_t threshold_size;
+    uint64_t threshold_size;
 
     /* params from 'migrate-set-parameters' */
     MigrationParameters parameters;
@@ -528,6 +524,7 @@ int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
 void migration_make_urgent_request(void);
 void migration_consume_urgent_request(void);
 bool migration_rate_limit(void);
+void migration_bh_schedule(QEMUBHFunc *cb, void *opaque);
 void migration_cancel(const Error *error);
 
 void migration_populate_vfio_info(MigrationInfo *info);

migration/postcopy-ram.c

@@ -102,11 +102,9 @@ void postcopy_thread_create(MigrationIncomingState *mis,
  * are target OS specific.
  */
 #if defined(__linux__)
-
 #include <poll.h>
 #include <sys/ioctl.h>
 #include <sys/syscall.h>
-#include <asm/types.h> /* for __u64 */
 #endif
 
 #if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
@@ -272,8 +270,8 @@ static bool request_ufd_features(int ufd, uint64_t features)
         return false;
     }
 
-    ioctl_mask = (__u64)1 << _UFFDIO_REGISTER |
+    ioctl_mask = 1ULL << _UFFDIO_REGISTER |
-                 (__u64)1 << _UFFDIO_UNREGISTER;
+                 1ULL << _UFFDIO_UNREGISTER;
     if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) {
         error_report("Missing userfault features: %" PRIx64,
                      (uint64_t)(~api_struct.ioctls & ioctl_mask));
@@ -462,9 +460,9 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, Error **errp)
         goto out;
     }
 
-    feature_mask = (__u64)1 << _UFFDIO_WAKE |
+    feature_mask = 1ULL << _UFFDIO_WAKE |
-                   (__u64)1 << _UFFDIO_COPY |
+                   1ULL << _UFFDIO_COPY |
-                   (__u64)1 << _UFFDIO_ZEROPAGE;
+                   1ULL << _UFFDIO_ZEROPAGE;
     if ((reg_struct.ioctls & feature_mask) != feature_mask) {
         error_setg(errp, "Missing userfault map features: %" PRIx64,
                    (uint64_t)(~reg_struct.ioctls & feature_mask));
@@ -733,11 +731,11 @@ static int ram_block_enable_notify(RAMBlock *rb, void *opaque)
         error_report("%s userfault register: %s", __func__, strerror(errno));
         return -1;
     }
-    if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
+    if (!(reg_struct.ioctls & (1ULL << _UFFDIO_COPY))) {
         error_report("%s userfault: Region doesn't support COPY", __func__);
         return -1;
     }
-    if (reg_struct.ioctls & ((__u64)1 << _UFFDIO_ZEROPAGE)) {
+    if (reg_struct.ioctls & (1ULL << _UFFDIO_ZEROPAGE)) {
         qemu_ram_set_uf_zeroable(rb);
     }
 

migration/ram.c

@@ -3213,21 +3213,20 @@ static void ram_state_pending_estimate(void *opaque, uint64_t *must_precopy,
 static void ram_state_pending_exact(void *opaque, uint64_t *must_precopy,
                                     uint64_t *can_postcopy)
 {
-    MigrationState *s = migrate_get_current();
     RAMState **temp = opaque;
     RAMState *rs = *temp;
+    uint64_t remaining_size;
 
-    uint64_t remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
+    if (!migration_in_postcopy()) {
-
-    if (!migration_in_postcopy() && remaining_size < s->threshold_size) {
         bql_lock();
         WITH_RCU_READ_LOCK_GUARD() {
             migration_bitmap_sync_precopy(rs, false);
         }
         bql_unlock();
-        remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
     }
 
+    remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
+
     if (migrate_postcopy_ram()) {
         /* We can do postcopy, and all the data is postcopiable */
         *can_postcopy += remaining_size;

migration/savevm.c

@@ -2171,8 +2171,6 @@ static void loadvm_postcopy_handle_run_bh(void *opaque)
         runstate_set(RUN_STATE_PAUSED);
     }
 
-    qemu_bh_delete(mis->bh);
-
     trace_vmstate_downtime_checkpoint("dst-postcopy-bh-vm-started");
 }
 
@@ -2188,8 +2186,7 @@ static int loadvm_postcopy_handle_run(MigrationIncomingState *mis)
     }
 
     postcopy_state_set(POSTCOPY_INCOMING_RUNNING);
-    mis->bh = qemu_bh_new(loadvm_postcopy_handle_run_bh, mis);
+    migration_bh_schedule(loadvm_postcopy_handle_run_bh, mis);
-    qemu_bh_schedule(mis->bh);
 
     /* We need to finish reading the stream from the package
      * and also stop reading anything more from the stream that loaded the

migration/yank_functions.c

@@ -8,12 +8,9 @@
  */
 
 #include "qemu/osdep.h"
-#include "qapi/error.h"
 #include "io/channel.h"
 #include "yank_functions.h"
 #include "qemu/yank.h"
-#include "io/channel-socket.h"
-#include "io/channel-tls.h"
 #include "qemu-file.h"
 
 void migration_yank_iochannel(void *opaque)
@@ -26,8 +23,7 @@ void migration_yank_iochannel(void *opaque)
 /* Return whether yank is supported on this ioc */
 static bool migration_ioc_yank_supported(QIOChannel *ioc)
 {
-    return object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET) ||
+    return qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_SHUTDOWN);
-        object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS);
 }
 
 void migration_ioc_register_yank(QIOChannel *ioc)

qapi/migration.json

@@ -1757,7 +1757,7 @@
 #
 ##
 { 'command': 'migrate',
-  'data': {'uri': 'str',
+  'data': {'*uri': 'str',
            '*channels': [ 'MigrationChannel' ],
            '*blk': { 'type': 'bool', 'features': [ 'deprecated' ] },
            '*inc': { 'type': 'bool', 'features': [ 'deprecated' ] },

scripts/analyze-migration.py

@@ -151,17 +151,12 @@ class RamSection(object):
             addr &= ~(self.TARGET_PAGE_SIZE - 1)
 
             if flags & self.RAM_SAVE_FLAG_MEM_SIZE:
-                while True:
+                total_length = addr
+                while total_length > 0:
                     namelen = self.file.read8()
-                    # We assume that no RAM chunk is big enough to ever
-                    # hit the first byte of the address, so when we see
-                    # a zero here we know it has to be an address, not the
-                    # length of the next block.
-                    if namelen == 0:
-                        self.file.file.seek(-1, 1)
-                        break
                     self.name = self.file.readstr(len = namelen)
                     len = self.file.read64()
+                    total_length -= len
                     self.sizeinfo[self.name] = '0x%016x' % len
                     if self.write_memory:
                         print(self.name)

subprojects/libvhost-user/libvhost-user.c

@@ -684,7 +684,7 @@ generate_faults(VuDev *dev) {
                      dev->postcopy_ufd, strerror(errno));
             return false;
         }
-        if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
+        if (!(reg_struct.ioctls & (1ULL << _UFFDIO_COPY))) {
             vu_panic(dev, "%s Region (%d) doesn't support COPY",
                      __func__, i);
             return false;

tests/qtest/migration-test.c

@@ -104,8 +104,8 @@ static bool ufd_version_check(void)
     }
     uffd_feature_thread_id = api_struct.features & UFFD_FEATURE_THREAD_ID;
 
-    ioctl_mask = (__u64)1 << _UFFDIO_REGISTER |
+    ioctl_mask = 1ULL << _UFFDIO_REGISTER |
-                 (__u64)1 << _UFFDIO_UNREGISTER;
+                 1ULL << _UFFDIO_UNREGISTER;
     if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) {
         g_test_message("Skipping test: Missing userfault feature");
         return false;