[PULL 00/16] vfio queue

[PULL 00/16] vfio queue

[Cédric Le Goater]

The following changes since commit 4d541f63e90c81112c298cbb35ed53e9c79deb00:

  Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging (2023-06-29 13:16:06 +0200)

are available in the Git repository at:

  https://github.com/legoater/qemu/ tags/pull-vfio-20230630

for you to fetch changes up to 0cc889c8826cefa5b80110d31a62273b56aa1832:

  vfio/pci: Free leaked timer in vfio_realize error path (2023-06-30 06:02:51 +0200)

----------------------------------------------------------------
vfio queue:

* migration: New switchover ack to reduce downtime
* VFIO migration pre-copy support
* Removal of the VFIO migration experimental flag
* Alternate offset for GPUDirect Cliques
* Misc fixes

----------------------------------------------------------------
Alex Williamson (3):
      vfio: Implement a common device info helper
      hw/vfio/pci-quirks: Support alternate offset for GPUDirect Cliques
      MAINTAINERS: Promote Cédric to VFIO co-maintainer

Avihai Horon (10):
      migration: Add switchover ack capability
      migration: Implement switchover ack logic
      migration: Enable switchover ack capability
      tests: Add migration switchover ack capability test
      vfio/migration: Refactor vfio_save_block() to return saved data size
      vfio/migration: Store VFIO migration flags in VFIOMigration
      vfio/migration: Add VFIO migration pre-copy support
      vfio/migration: Add support for switchover ack capability
      vfio/migration: Reset bytes_transferred properly
      vfio/migration: Make VFIO migration non-experimental

Shameer Kolothum (1):
      vfio/pci: Call vfio_prepare_kvm_msi_virq_batch() in MSI retry path

Zhenzhong Duan (2):
      vfio/pci: Fix a segfault in vfio_realize
      vfio/pci: Free leaked timer in vfio_realize error path

 MAINTAINERS                   |   2 +-
 docs/devel/vfio-migration.rst |  45 +++++--
 qapi/migration.json           |  12 +-
 include/hw/vfio/vfio-common.h |  12 +-
 include/migration/register.h  |   2 +
 migration/migration.h         |  15 +++
 migration/options.h           |   1 +
 migration/savevm.h            |   1 +
 hw/s390x/s390-pci-vfio.c      |  37 +----
 hw/vfio/common.c              |  68 +++++++---
 hw/vfio/migration.c           | 305 ++++++++++++++++++++++++++++++++++++------
 hw/vfio/pci-quirks.c          |  41 +++++-
 hw/vfio/pci.c                 |  15 ++-
 migration/migration.c         |  33 ++++-
 migration/options.c           |  17 +++
 migration/savevm.c            |  55 ++++++++
 migration/target.c            |  17 ++-
 tests/qtest/migration-test.c  |  31 +++++
 hw/vfio/trace-events          |   6 +-
 migration/trace-events        |   3 +
 20 files changed, 600 insertions(+), 118 deletions(-)

[PULL 01/16] migration: Add switchover ack capability

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Migration downtime estimation is calculated based on bandwidth and
remaining migration data. This assumes that loading of migration data in
the destination takes a negligible amount of time and that downtime
depends only on network speed.

While this may be true for RAM, it's not necessarily true for other
migrated devices. For example, loading the data of a VFIO device in the
destination might require from the device to allocate resources, prepare
internal data structures and so on. These operations can take a
significant amount of time which can increase migration downtime.

This patch adds a new capability "switchover ack" that prevents the
source from stopping the VM and completing the migration until an ACK
is received from the destination that it's OK to do so.

This can be used by migrated devices in various ways to reduce downtime.
For example, a device can send initial precopy metadata to pre-allocate
resources in the destination and use this capability to make sure that
the pre-allocation is completed before the source VM is stopped, so it
will have full effect.

This new capability relies on the return path capability to communicate
from the destination back to the source.

The actual implementation of the capability will be added in the
following patches.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 qapi/migration.json | 12 +++++++++++-
 migration/options.h |  1 +
 migration/options.c | 21 +++++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/qapi/migration.json b/qapi/migration.json
index 5bb5ab82a0cf..47dfef02780f 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -487,6 +487,16 @@
 #     and should not affect the correctness of postcopy migration.
 #     (since 7.1)
 #
+# @switchover-ack: If enabled, migration will not stop the source VM
+#     and complete the migration until an ACK is received from the
+#     destination that it's OK to do so.  Exactly when this ACK is
+#     sent depends on the migrated devices that use this feature.
+#     For example, a device can use it to make sure some of its data
+#     is sent and loaded in the destination before doing switchover.
+#     This can reduce downtime if devices that support this capability
+#     are present.  'return-path' capability must be enabled to use
+#     it.  (since 8.1)
+#
 # Features:
 #
 # @unstable: Members @x-colo and @x-ignore-shared are experimental.
@@ -502,7 +512,7 @@
            'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
            { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
            'validate-uuid', 'background-snapshot',
-           'zero-copy-send', 'postcopy-preempt'] }
+           'zero-copy-send', 'postcopy-preempt', 'switchover-ack'] }
 
 ##
 # @MigrationCapabilityStatus:
diff --git a/migration/options.h b/migration/options.h
index 45991af3c208..9aaf363322b4 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -40,6 +40,7 @@ bool migrate_postcopy_ram(void);
 bool migrate_rdma_pin_all(void);
 bool migrate_release_ram(void);
 bool migrate_return_path(void);
+bool migrate_switchover_ack(void);
 bool migrate_validate_uuid(void);
 bool migrate_xbzrle(void);
 bool migrate_zero_blocks(void);
diff --git a/migration/options.c b/migration/options.c
index b62ab30cd585..16007afca662 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -185,6 +185,8 @@ Property migration_properties[] = {
     DEFINE_PROP_MIG_CAP("x-zero-copy-send",
             MIGRATION_CAPABILITY_ZERO_COPY_SEND),
 #endif
+    DEFINE_PROP_MIG_CAP("x-switchover-ack",
+                        MIGRATION_CAPABILITY_SWITCHOVER_ACK),
 
     DEFINE_PROP_END_OF_LIST(),
 };
@@ -308,6 +310,13 @@ bool migrate_return_path(void)
     return s->capabilities[MIGRATION_CAPABILITY_RETURN_PATH];
 }
 
+bool migrate_switchover_ack(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->capabilities[MIGRATION_CAPABILITY_SWITCHOVER_ACK];
+}
+
 bool migrate_validate_uuid(void)
 {
     MigrationState *s = migrate_get_current();
@@ -547,6 +556,18 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp)
         }
     }
 
+    if (new_caps[MIGRATION_CAPABILITY_SWITCHOVER_ACK]) {
+        if (!new_caps[MIGRATION_CAPABILITY_RETURN_PATH]) {
+            error_setg(errp, "Capability 'switchover-ack' requires capability "
+                             "'return-path'");
+            return false;
+        }
+
+        /* Disable this capability until it's implemented */
+        error_setg(errp, "'switchover-ack' is not implemented yet");
+        return false;
+    }
+
     return true;
 }
 
-- 
2.41.0

[PULL 02/16] migration: Implement switchover ack logic

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Implement switchover ack logic. This prevents the source from stopping
the VM and completing the migration until an ACK is received from the
destination that it's OK to do so.

To achieve this, a new SaveVMHandlers handler switchover_ack_needed()
and a new return path message MIG_RP_MSG_SWITCHOVER_ACK are added.

The switchover_ack_needed() handler is called during migration setup in
the destination to check if switchover ack is used by the migrated
device.

When switchover is approved by all migrated devices in the destination
that support this capability, the MIG_RP_MSG_SWITCHOVER_ACK return path
message is sent to the source to notify it that it's OK to do
switchover.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/migration/register.h |  2 ++
 migration/migration.h        | 14 ++++++++++
 migration/savevm.h           |  1 +
 migration/migration.c        | 32 +++++++++++++++++++--
 migration/savevm.c           | 54 ++++++++++++++++++++++++++++++++++++
 migration/trace-events       |  3 ++
 6 files changed, 104 insertions(+), 2 deletions(-)

diff --git a/include/migration/register.h b/include/migration/register.h
index a8dfd8fefd0a..90914f32f50c 100644
--- a/include/migration/register.h
+++ b/include/migration/register.h
@@ -71,6 +71,8 @@ typedef struct SaveVMHandlers {
     int (*load_cleanup)(void *opaque);
     /* Called when postcopy migration wants to resume from failure */
     int (*resume_prepare)(MigrationState *s, void *opaque);
+    /* Checks if switchover ack should be used. Called only in dest */
+    bool (*switchover_ack_needed)(void *opaque);
 } SaveVMHandlers;
 
 int register_savevm_live(const char *idstr,
diff --git a/migration/migration.h b/migration/migration.h
index 30c3e97635b1..c859a0d35eb7 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -210,6 +210,13 @@ struct MigrationIncomingState {
      * contains valid information.
      */
     QemuMutex page_request_mutex;
+
+    /*
+     * Number of devices that have yet to approve switchover. When this reaches
+     * zero an ACK that it's OK to do switchover is sent to the source. No lock
+     * is needed as this field is updated serially.
+     */
+    unsigned int switchover_ack_pending_num;
 };
 
 MigrationIncomingState *migration_incoming_get_current(void);
@@ -440,6 +447,12 @@ struct MigrationState {
 
     /* QEMU_VM_VMDESCRIPTION content filled for all non-iterable devices. */
     JSONWriter *vmdesc;
+
+    /*
+     * Indicates whether an ACK from the destination that it's OK to do
+     * switchover has been received.
+     */
+    bool switchover_acked;
 };
 
 void migrate_set_state(int *state, int old_state, int new_state);
@@ -480,6 +493,7 @@ int migrate_send_rp_message_req_pages(MigrationIncomingState *mis,
 void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis,
                                  char *block_name);
 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value);
+int migrate_send_rp_switchover_ack(MigrationIncomingState *mis);
 
 void dirty_bitmap_mig_before_vm_start(void);
 void dirty_bitmap_mig_cancel_outgoing(void);
diff --git a/migration/savevm.h b/migration/savevm.h
index fb636735f0af..e894bbc14331 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -65,6 +65,7 @@ int qemu_loadvm_state(QEMUFile *f);
 void qemu_loadvm_state_cleanup(void);
 int qemu_loadvm_state_main(QEMUFile *f, MigrationIncomingState *mis);
 int qemu_load_device_state(QEMUFile *f);
+int qemu_loadvm_approve_switchover(void);
 int qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
         bool in_postcopy, bool inactivate_disks);
 
diff --git a/migration/migration.c b/migration/migration.c
index dc05c6f6ea94..7653787f745d 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -78,6 +78,7 @@ enum mig_rp_message_type {
     MIG_RP_MSG_REQ_PAGES,    /* data (start: be64, len: be32) */
     MIG_RP_MSG_RECV_BITMAP,  /* send recved_bitmap back to source */
     MIG_RP_MSG_RESUME_ACK,   /* tell source that we are ready to resume */
+    MIG_RP_MSG_SWITCHOVER_ACK, /* Tell source it's OK to do switchover */
 
     MIG_RP_MSG_MAX
 };
@@ -760,6 +761,11 @@ bool migration_has_all_channels(void)
     return true;
 }
 
+int migrate_send_rp_switchover_ack(MigrationIncomingState *mis)
+{
+    return migrate_send_rp_message(mis, MIG_RP_MSG_SWITCHOVER_ACK, 0, NULL);
+}
+
 /*
  * Send a 'SHUT' message on the return channel with the given value
  * to indicate that we've finished with the RP.  Non-0 value indicates
@@ -1405,6 +1411,7 @@ void migrate_init(MigrationState *s)
     s->vm_old_state = -1;
     s->iteration_initial_bytes = 0;
     s->threshold_size = 0;
+    s->switchover_acked = false;
 }
 
 int migrate_add_blocker_internal(Error *reason, Error **errp)
@@ -1721,6 +1728,7 @@ static struct rp_cmd_args {
     [MIG_RP_MSG_REQ_PAGES_ID]   = { .len = -1, .name = "REQ_PAGES_ID" },
     [MIG_RP_MSG_RECV_BITMAP]    = { .len = -1, .name = "RECV_BITMAP" },
     [MIG_RP_MSG_RESUME_ACK]     = { .len =  4, .name = "RESUME_ACK" },
+    [MIG_RP_MSG_SWITCHOVER_ACK] = { .len =  0, .name = "SWITCHOVER_ACK" },
     [MIG_RP_MSG_MAX]            = { .len = -1, .name = "MAX" },
 };
 
@@ -1959,6 +1967,11 @@ retry:
             }
             break;
 
+        case MIG_RP_MSG_SWITCHOVER_ACK:
+            ms->switchover_acked = true;
+            trace_source_return_path_thread_switchover_acked();
+            break;
+
         default:
             break;
         }
@@ -2693,6 +2706,20 @@ static void migration_update_counters(MigrationState *s,
                               bandwidth, s->threshold_size);
 }
 
+static bool migration_can_switchover(MigrationState *s)
+{
+    if (!migrate_switchover_ack()) {
+        return true;
+    }
+
+    /* No reason to wait for switchover ACK if VM is stopped */
+    if (!runstate_is_running()) {
+        return true;
+    }
+
+    return s->switchover_acked;
+}
+
 /* Migration thread iteration status */
 typedef enum {
     MIG_ITERATE_RESUME,         /* Resume current iteration */
@@ -2708,6 +2735,7 @@ static MigIterateState migration_iteration_run(MigrationState *s)
 {
     uint64_t must_precopy, can_postcopy;
     bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
+    bool can_switchover = migration_can_switchover(s);
 
     qemu_savevm_state_pending_estimate(&must_precopy, &can_postcopy);
     uint64_t pending_size = must_precopy + can_postcopy;
@@ -2720,14 +2748,14 @@ static MigIterateState migration_iteration_run(MigrationState *s)
         trace_migrate_pending_exact(pending_size, must_precopy, can_postcopy);
     }
 
-    if (!pending_size || pending_size < s->threshold_size) {
+    if ((!pending_size || pending_size < s->threshold_size) && can_switchover) {
         trace_migration_thread_low_pending(pending_size);
         migration_completion(s);
         return MIG_ITERATE_BREAK;
     }
 
     /* Still a significant amount to transfer */
-    if (!in_postcopy && must_precopy <= s->threshold_size &&
+    if (!in_postcopy && must_precopy <= s->threshold_size && can_switchover &&
         qatomic_read(&s->start_postcopy)) {
         if (postcopy_start(s)) {
             error_report("%s: postcopy failed to start", __func__);
diff --git a/migration/savevm.c b/migration/savevm.c
index bc284087f9b9..cdf47939244d 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2360,6 +2360,21 @@ static int loadvm_process_command(QEMUFile *f)
             error_report("CMD_OPEN_RETURN_PATH failed");
             return -1;
         }
+
+        /*
+         * Switchover ack is enabled but no device uses it, so send an ACK to
+         * source that it's OK to switchover. Do it here, after return path has
+         * been created.
+         */
+        if (migrate_switchover_ack() && !mis->switchover_ack_pending_num) {
+            int ret = migrate_send_rp_switchover_ack(mis);
+            if (ret) {
+                error_report(
+                    "Could not send switchover ack RP MSG, err %d (%s)", ret,
+                    strerror(-ret));
+                return ret;
+            }
+        }
         break;
 
     case MIG_CMD_PING:
@@ -2586,6 +2601,23 @@ static int qemu_loadvm_state_header(QEMUFile *f)
     return 0;
 }
 
+static void qemu_loadvm_state_switchover_ack_needed(MigrationIncomingState *mis)
+{
+    SaveStateEntry *se;
+
+    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
+        if (!se->ops || !se->ops->switchover_ack_needed) {
+            continue;
+        }
+
+        if (se->ops->switchover_ack_needed(se->opaque)) {
+            mis->switchover_ack_pending_num++;
+        }
+    }
+
+    trace_loadvm_state_switchover_ack_needed(mis->switchover_ack_pending_num);
+}
+
 static int qemu_loadvm_state_setup(QEMUFile *f)
 {
     SaveStateEntry *se;
@@ -2789,6 +2821,10 @@ int qemu_loadvm_state(QEMUFile *f)
         return -EINVAL;
     }
 
+    if (migrate_switchover_ack()) {
+        qemu_loadvm_state_switchover_ack_needed(mis);
+    }
+
     cpu_synchronize_all_pre_loadvm();
 
     ret = qemu_loadvm_state_main(f, mis);
@@ -2862,6 +2898,24 @@ int qemu_load_device_state(QEMUFile *f)
     return 0;
 }
 
+int qemu_loadvm_approve_switchover(void)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+
+    if (!mis->switchover_ack_pending_num) {
+        return -EINVAL;
+    }
+
+    mis->switchover_ack_pending_num--;
+    trace_loadvm_approve_switchover(mis->switchover_ack_pending_num);
+
+    if (mis->switchover_ack_pending_num) {
+        return 0;
+    }
+
+    return migrate_send_rp_switchover_ack(mis);
+}
+
 bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
                   bool has_devices, strList *devices, Error **errp)
 {
diff --git a/migration/trace-events b/migration/trace-events
index cdaef7a1ea41..5259c1044b08 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -7,6 +7,7 @@ qemu_loadvm_state_section_partend(uint32_t section_id) "%u"
 qemu_loadvm_state_post_main(int ret) "%d"
 qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, uint32_t instance_id, uint32_t version_id) "%u(%s) %u %u"
 qemu_savevm_send_packaged(void) ""
+loadvm_state_switchover_ack_needed(unsigned int switchover_ack_pending_num) "Switchover ack pending num=%u"
 loadvm_state_setup(void) ""
 loadvm_state_cleanup(void) ""
 loadvm_handle_cmd_packaged(unsigned int length) "%u"
@@ -23,6 +24,7 @@ loadvm_postcopy_ram_handle_discard_end(void) ""
 loadvm_postcopy_ram_handle_discard_header(const char *ramid, uint16_t len) "%s: %ud"
 loadvm_process_command(const char *s, uint16_t len) "com=%s len=%d"
 loadvm_process_command_ping(uint32_t val) "0x%x"
+loadvm_approve_switchover(unsigned int switchover_ack_pending_num) "Switchover ack pending num=%u"
 postcopy_ram_listen_thread_exit(void) ""
 postcopy_ram_listen_thread_start(void) ""
 qemu_savevm_send_postcopy_advise(void) ""
@@ -180,6 +182,7 @@ source_return_path_thread_loop_top(void) ""
 source_return_path_thread_pong(uint32_t val) "0x%x"
 source_return_path_thread_shut(uint32_t val) "0x%x"
 source_return_path_thread_resume_ack(uint32_t v) "%"PRIu32
+source_return_path_thread_switchover_acked(void) ""
 migration_thread_low_pending(uint64_t pending) "%" PRIu64
 migrate_transferred(uint64_t tranferred, uint64_t time_spent, uint64_t bandwidth, uint64_t size) "transferred %" PRIu64 " time_spent %" PRIu64 " bandwidth %" PRIu64 " max_size %" PRId64
 process_incoming_migration_co_end(int ret, int ps) "ret=%d postcopy-state=%d"
-- 
2.41.0

[PULL 03/16] migration: Enable switchover ack capability

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Now that switchover ack logic has been implemented, enable the
capability.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 migration/options.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/migration/options.c b/migration/options.c
index 16007afca662..5a9505adf7a8 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -562,10 +562,6 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp)
                              "'return-path'");
             return false;
         }
-
-        /* Disable this capability until it's implemented */
-        error_setg(errp, "'switchover-ack' is not implemented yet");
-        return false;
     }
 
     return true;
-- 
2.41.0

[PULL 04/16] tests: Add migration switchover ack capability test

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Add migration switchover ack capability test. The test runs without
devices that support this capability, but is still useful to make sure
it didn't break anything.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 tests/qtest/migration-test.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index b0c355bbd9ca..b9cc194100b5 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -1693,6 +1693,33 @@ static void test_precopy_tcp_plain(void)
     test_precopy_common(&args);
 }
 
+static void *test_migrate_switchover_ack_start(QTestState *from, QTestState *to)
+{
+
+    migrate_set_capability(from, "return-path", true);
+    migrate_set_capability(to, "return-path", true);
+
+    migrate_set_capability(from, "switchover-ack", true);
+    migrate_set_capability(to, "switchover-ack", true);
+
+    return NULL;
+}
+
+static void test_precopy_tcp_switchover_ack(void)
+{
+    MigrateCommon args = {
+        .listen_uri = "tcp:127.0.0.1:0",
+        .start_hook = test_migrate_switchover_ack_start,
+        /*
+         * Source VM must be running in order to consider the switchover ACK
+         * when deciding to do switchover or not.
+         */
+        .live = true,
+    };
+
+    test_precopy_common(&args);
+}
+
 #ifdef CONFIG_GNUTLS
 static void test_precopy_tcp_tls_psk_match(void)
 {
@@ -2737,6 +2764,10 @@ int main(int argc, char **argv)
 #endif /* CONFIG_GNUTLS */
 
     qtest_add_func("/migration/precopy/tcp/plain", test_precopy_tcp_plain);
+
+    qtest_add_func("/migration/precopy/tcp/plain/switchover-ack",
+                   test_precopy_tcp_switchover_ack);
+
 #ifdef CONFIG_GNUTLS
     qtest_add_func("/migration/precopy/tcp/tls/psk/match",
                    test_precopy_tcp_tls_psk_match);
-- 
2.41.0

[PULL 05/16] vfio/migration: Refactor vfio_save_block() to return saved data size

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Refactor vfio_save_block() to return the size of saved data on success
and -errno on error.

This will be used in next patch to implement VFIO migration pre-copy
support.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/migration.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 6b58dddb8859..235978fd6805 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -241,8 +241,8 @@ static int vfio_query_stop_copy_size(VFIODevice *vbasedev,
     return 0;
 }
 
-/* Returns 1 if end-of-stream is reached, 0 if more data and -errno if error */
-static int vfio_save_block(QEMUFile *f, VFIOMigration *migration)
+/* Returns the size of saved data on success and -errno on error */
+static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
 {
     ssize_t data_size;
 
@@ -252,7 +252,7 @@ static int vfio_save_block(QEMUFile *f, VFIOMigration *migration)
         return -errno;
     }
     if (data_size == 0) {
-        return 1;
+        return 0;
     }
 
     qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
@@ -262,7 +262,7 @@ static int vfio_save_block(QEMUFile *f, VFIOMigration *migration)
 
     trace_vfio_save_block(migration->vbasedev->name, data_size);
 
-    return qemu_file_get_error(f);
+    return qemu_file_get_error(f) ?: data_size;
 }
 
 /* ---------------------------------------------------------------------- */
@@ -335,6 +335,7 @@ static void vfio_state_pending_exact(void *opaque, uint64_t *must_precopy,
 static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
 {
     VFIODevice *vbasedev = opaque;
+    ssize_t data_size;
     int ret;
 
     /* We reach here with device state STOP only */
@@ -345,11 +346,11 @@ static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
     }
 
     do {
-        ret = vfio_save_block(f, vbasedev->migration);
-        if (ret < 0) {
-            return ret;
+        data_size = vfio_save_block(f, vbasedev->migration);
+        if (data_size < 0) {
+            return data_size;
         }
-    } while (!ret);
+    } while (data_size);
 
     qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
     ret = qemu_file_get_error(f);
-- 
2.41.0

[PULL 06/16] vfio/migration: Store VFIO migration flags in VFIOMigration

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

VFIO migration flags are queried once in vfio_migration_init(). Store
them in VFIOMigration so they can be used later to check the device's
migration capabilities without re-querying them.

This will be used in the next patch to check if the device supports
precopy migration.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/hw/vfio/vfio-common.h | 1 +
 hw/vfio/migration.c           | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index eed244f25f34..5f29dab83913 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -66,6 +66,7 @@ typedef struct VFIOMigration {
     int data_fd;
     void *data_buffer;
     size_t data_buffer_size;
+    uint64_t mig_flags;
 } VFIOMigration;
 
 typedef struct VFIOAddressSpace {
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 235978fd6805..8d3341437926 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -603,6 +603,7 @@ static int vfio_migration_init(VFIODevice *vbasedev)
     migration->vbasedev = vbasedev;
     migration->device_state = VFIO_DEVICE_STATE_RUNNING;
     migration->data_fd = -1;
+    migration->mig_flags = mig_flags;
 
     vbasedev->dirty_pages_supported = vfio_dma_logging_supported(vbasedev);
 
-- 
2.41.0

[PULL 07/16] vfio/migration: Add VFIO migration pre-copy support

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Pre-copy support allows the VFIO device data to be transferred while the
VM is running. This helps to accommodate VFIO devices that have a large
amount of data that needs to be transferred, and it can reduce migration
downtime.

Pre-copy support is optional in VFIO migration protocol v2.
Implement pre-copy of VFIO migration protocol v2 and use it for devices
that support it. Full description of it can be found in the following
Linux commit: 4db52602a607 ("vfio: Extend the device migration protocol
with PRE_COPY").

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 docs/devel/vfio-migration.rst |  35 +++++---
 include/hw/vfio/vfio-common.h |   2 +
 hw/vfio/common.c              |   6 +-
 hw/vfio/migration.c           | 165 ++++++++++++++++++++++++++++++++--
 hw/vfio/trace-events          |   4 +-
 5 files changed, 190 insertions(+), 22 deletions(-)

diff --git a/docs/devel/vfio-migration.rst b/docs/devel/vfio-migration.rst
index 1b68ccf11529..e896b2a6734b 100644
--- a/docs/devel/vfio-migration.rst
+++ b/docs/devel/vfio-migration.rst
@@ -7,12 +7,14 @@ the guest is running on source host and restoring this saved state on the
 destination host. This document details how saving and restoring of VFIO
 devices is done in QEMU.
 
-Migration of VFIO devices currently consists of a single stop-and-copy phase.
-During the stop-and-copy phase the guest is stopped and the entire VFIO device
-data is transferred to the destination.
-
-The pre-copy phase of migration is currently not supported for VFIO devices.
-Support for VFIO pre-copy will be added later on.
+Migration of VFIO devices consists of two phases: the optional pre-copy phase,
+and the stop-and-copy phase. The pre-copy phase is iterative and allows to
+accommodate VFIO devices that have a large amount of data that needs to be
+transferred. The iterative pre-copy phase of migration allows for the guest to
+continue whilst the VFIO device state is transferred to the destination, this
+helps to reduce the total downtime of the VM. VFIO devices opt-in to pre-copy
+support by reporting the VFIO_MIGRATION_PRE_COPY flag in the
+VFIO_DEVICE_FEATURE_MIGRATION ioctl.
 
 Note that currently VFIO migration is supported only for a single device. This
 is due to VFIO migration's lack of P2P support. However, P2P support is planned
@@ -29,10 +31,20 @@ VFIO implements the device hooks for the iterative approach as follows:
 * A ``load_setup`` function that sets the VFIO device on the destination in
   _RESUMING state.
 
+* A ``state_pending_estimate`` function that reports an estimate of the
+  remaining pre-copy data that the vendor driver has yet to save for the VFIO
+  device.
+
 * A ``state_pending_exact`` function that reads pending_bytes from the vendor
   driver, which indicates the amount of data that the vendor driver has yet to
   save for the VFIO device.
 
+* An ``is_active_iterate`` function that indicates ``save_live_iterate`` is
+  active only when the VFIO device is in pre-copy states.
+
+* A ``save_live_iterate`` function that reads the VFIO device's data from the
+  vendor driver during iterative pre-copy phase.
+
 * A ``save_state`` function to save the device config space if it is present.
 
 * A ``save_live_complete_precopy`` function that sets the VFIO device in
@@ -111,8 +123,10 @@ Flow of state changes during Live migration
 ===========================================
 
 Below is the flow of state change during live migration.
-The values in the brackets represent the VM state, the migration state, and
+The values in the parentheses represent the VM state, the migration state, and
 the VFIO device state, respectively.
+The text in the square brackets represents the flow if the VFIO device supports
+pre-copy.
 
 Live migration save path
 ------------------------
@@ -124,11 +138,12 @@ Live migration save path
                                   |
                      migrate_init spawns migration_thread
                 Migration thread then calls each device's .save_setup()
-                       (RUNNING, _SETUP, _RUNNING)
+                  (RUNNING, _SETUP, _RUNNING [_PRE_COPY])
                                   |
-                      (RUNNING, _ACTIVE, _RUNNING)
-             If device is active, get pending_bytes by .state_pending_exact()
+                  (RUNNING, _ACTIVE, _RUNNING [_PRE_COPY])
+      If device is active, get pending_bytes by .state_pending_{estimate,exact}()
           If total pending_bytes >= threshold_size, call .save_live_iterate()
+                  [Data of VFIO device for pre-copy phase is copied]
         Iterate till total pending bytes converge and are less than threshold
                                   |
   On migration completion, vCPU stops and calls .save_live_complete_precopy for
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 5f29dab83913..1db901c1941f 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -67,6 +67,8 @@ typedef struct VFIOMigration {
     void *data_buffer;
     size_t data_buffer_size;
     uint64_t mig_flags;
+    uint64_t precopy_init_size;
+    uint64_t precopy_dirty_size;
 } VFIOMigration;
 
 typedef struct VFIOAddressSpace {
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index fa8fd949b1cf..25801de173c4 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -492,7 +492,8 @@ static bool vfio_devices_all_dirty_tracking(VFIOContainer *container)
             }
 
             if (vbasedev->pre_copy_dirty_page_tracking == ON_OFF_AUTO_OFF &&
-                migration->device_state == VFIO_DEVICE_STATE_RUNNING) {
+                (migration->device_state == VFIO_DEVICE_STATE_RUNNING ||
+                 migration->device_state == VFIO_DEVICE_STATE_PRE_COPY)) {
                 return false;
             }
         }
@@ -537,7 +538,8 @@ static bool vfio_devices_all_running_and_mig_active(VFIOContainer *container)
                 return false;
             }
 
-            if (migration->device_state == VFIO_DEVICE_STATE_RUNNING) {
+            if (migration->device_state == VFIO_DEVICE_STATE_RUNNING ||
+                migration->device_state == VFIO_DEVICE_STATE_PRE_COPY) {
                 continue;
             } else {
                 return false;
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 8d3341437926..d8f6a22ae14e 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -68,6 +68,8 @@ static const char *mig_state_to_str(enum vfio_device_mig_state state)
         return "STOP_COPY";
     case VFIO_DEVICE_STATE_RESUMING:
         return "RESUMING";
+    case VFIO_DEVICE_STATE_PRE_COPY:
+        return "PRE_COPY";
     default:
         return "UNKNOWN STATE";
     }
@@ -241,6 +243,25 @@ static int vfio_query_stop_copy_size(VFIODevice *vbasedev,
     return 0;
 }
 
+static int vfio_query_precopy_size(VFIOMigration *migration)
+{
+    struct vfio_precopy_info precopy = {
+        .argsz = sizeof(precopy),
+    };
+
+    migration->precopy_init_size = 0;
+    migration->precopy_dirty_size = 0;
+
+    if (ioctl(migration->data_fd, VFIO_MIG_GET_PRECOPY_INFO, &precopy)) {
+        return -errno;
+    }
+
+    migration->precopy_init_size = precopy.initial_bytes;
+    migration->precopy_dirty_size = precopy.dirty_bytes;
+
+    return 0;
+}
+
 /* Returns the size of saved data on success and -errno on error */
 static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
 {
@@ -249,6 +270,14 @@ static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
     data_size = read(migration->data_fd, migration->data_buffer,
                      migration->data_buffer_size);
     if (data_size < 0) {
+        /*
+         * Pre-copy emptied all the device state for now. For more information,
+         * please refer to the Linux kernel VFIO uAPI.
+         */
+        if (errno == ENOMSG) {
+            return 0;
+        }
+
         return -errno;
     }
     if (data_size == 0) {
@@ -265,6 +294,38 @@ static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
     return qemu_file_get_error(f) ?: data_size;
 }
 
+static void vfio_update_estimated_pending_data(VFIOMigration *migration,
+                                               uint64_t data_size)
+{
+    if (!data_size) {
+        /*
+         * Pre-copy emptied all the device state for now, update estimated sizes
+         * accordingly.
+         */
+        migration->precopy_init_size = 0;
+        migration->precopy_dirty_size = 0;
+
+        return;
+    }
+
+    if (migration->precopy_init_size) {
+        uint64_t init_size = MIN(migration->precopy_init_size, data_size);
+
+        migration->precopy_init_size -= init_size;
+        data_size -= init_size;
+    }
+
+    migration->precopy_dirty_size -= MIN(migration->precopy_dirty_size,
+                                         data_size);
+}
+
+static bool vfio_precopy_supported(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+
+    return migration->mig_flags & VFIO_MIGRATION_PRE_COPY;
+}
+
 /* ---------------------------------------------------------------------- */
 
 static int vfio_save_setup(QEMUFile *f, void *opaque)
@@ -285,6 +346,28 @@ static int vfio_save_setup(QEMUFile *f, void *opaque)
         return -ENOMEM;
     }
 
+    if (vfio_precopy_supported(vbasedev)) {
+        int ret;
+
+        switch (migration->device_state) {
+        case VFIO_DEVICE_STATE_RUNNING:
+            ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_PRE_COPY,
+                                           VFIO_DEVICE_STATE_RUNNING);
+            if (ret) {
+                return ret;
+            }
+
+            vfio_query_precopy_size(migration);
+
+            break;
+        case VFIO_DEVICE_STATE_STOP:
+            /* vfio_save_complete_precopy() will go to STOP_COPY */
+            break;
+        default:
+            return -EINVAL;
+        }
+    }
+
     trace_vfio_save_setup(vbasedev->name, migration->data_buffer_size);
 
     qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
@@ -299,26 +382,42 @@ static void vfio_save_cleanup(void *opaque)
 
     g_free(migration->data_buffer);
     migration->data_buffer = NULL;
+    migration->precopy_init_size = 0;
+    migration->precopy_dirty_size = 0;
     vfio_migration_cleanup(vbasedev);
     trace_vfio_save_cleanup(vbasedev->name);
 }
 
+static void vfio_state_pending_estimate(void *opaque, uint64_t *must_precopy,
+                                        uint64_t *can_postcopy)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+
+    if (migration->device_state != VFIO_DEVICE_STATE_PRE_COPY) {
+        return;
+    }
+
+    *must_precopy +=
+        migration->precopy_init_size + migration->precopy_dirty_size;
+
+    trace_vfio_state_pending_estimate(vbasedev->name, *must_precopy,
+                                      *can_postcopy,
+                                      migration->precopy_init_size,
+                                      migration->precopy_dirty_size);
+}
+
 /*
  * Migration size of VFIO devices can be as little as a few KBs or as big as
  * many GBs. This value should be big enough to cover the worst case.
  */
 #define VFIO_MIG_STOP_COPY_SIZE (100 * GiB)
 
-/*
- * Only exact function is implemented and not estimate function. The reason is
- * that during pre-copy phase of migration the estimate function is called
- * repeatedly while pending RAM size is over the threshold, thus migration
- * can't converge and querying the VFIO device pending data size is useless.
- */
 static void vfio_state_pending_exact(void *opaque, uint64_t *must_precopy,
                                      uint64_t *can_postcopy)
 {
     VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
     uint64_t stop_copy_size = VFIO_MIG_STOP_COPY_SIZE;
 
     /*
@@ -328,8 +427,48 @@ static void vfio_state_pending_exact(void *opaque, uint64_t *must_precopy,
     vfio_query_stop_copy_size(vbasedev, &stop_copy_size);
     *must_precopy += stop_copy_size;
 
+    if (migration->device_state == VFIO_DEVICE_STATE_PRE_COPY) {
+        vfio_query_precopy_size(migration);
+
+        *must_precopy +=
+            migration->precopy_init_size + migration->precopy_dirty_size;
+    }
+
     trace_vfio_state_pending_exact(vbasedev->name, *must_precopy, *can_postcopy,
-                                   stop_copy_size);
+                                   stop_copy_size, migration->precopy_init_size,
+                                   migration->precopy_dirty_size);
+}
+
+static bool vfio_is_active_iterate(void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+
+    return migration->device_state == VFIO_DEVICE_STATE_PRE_COPY;
+}
+
+static int vfio_save_iterate(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    ssize_t data_size;
+
+    data_size = vfio_save_block(f, migration);
+    if (data_size < 0) {
+        return data_size;
+    }
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    vfio_update_estimated_pending_data(migration, data_size);
+
+    trace_vfio_save_iterate(vbasedev->name, migration->precopy_init_size,
+                            migration->precopy_dirty_size);
+
+    /*
+     * A VFIO device's pre-copy dirty_bytes is not guaranteed to reach zero.
+     * Return 1 so following handlers will not be potentially blocked.
+     */
+    return 1;
 }
 
 static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
@@ -338,7 +477,7 @@ static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
     ssize_t data_size;
     int ret;
 
-    /* We reach here with device state STOP only */
+    /* We reach here with device state STOP or STOP_COPY only */
     ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_STOP_COPY,
                                    VFIO_DEVICE_STATE_STOP);
     if (ret) {
@@ -457,7 +596,10 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int version_id)
 static const SaveVMHandlers savevm_vfio_handlers = {
     .save_setup = vfio_save_setup,
     .save_cleanup = vfio_save_cleanup,
+    .state_pending_estimate = vfio_state_pending_estimate,
     .state_pending_exact = vfio_state_pending_exact,
+    .is_active_iterate = vfio_is_active_iterate,
+    .save_live_iterate = vfio_save_iterate,
     .save_live_complete_precopy = vfio_save_complete_precopy,
     .save_state = vfio_save_state,
     .load_setup = vfio_load_setup,
@@ -470,13 +612,18 @@ static const SaveVMHandlers savevm_vfio_handlers = {
 static void vfio_vmstate_change(void *opaque, bool running, RunState state)
 {
     VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
     enum vfio_device_mig_state new_state;
     int ret;
 
     if (running) {
         new_state = VFIO_DEVICE_STATE_RUNNING;
     } else {
-        new_state = VFIO_DEVICE_STATE_STOP;
+        new_state =
+            (migration->device_state == VFIO_DEVICE_STATE_PRE_COPY &&
+             (state == RUN_STATE_FINISH_MIGRATE || state == RUN_STATE_PAUSED)) ?
+                VFIO_DEVICE_STATE_STOP_COPY :
+                VFIO_DEVICE_STATE_STOP;
     }
 
     /*
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index cfb60c354de3..e328d644d289 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -162,6 +162,8 @@ vfio_save_block(const char *name, int data_size) " (%s) data_size %d"
 vfio_save_cleanup(const char *name) " (%s)"
 vfio_save_complete_precopy(const char *name, int ret) " (%s) ret %d"
 vfio_save_device_config_state(const char *name) " (%s)"
+vfio_save_iterate(const char *name, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy initial size 0x%"PRIx64" precopy dirty size 0x%"PRIx64
 vfio_save_setup(const char *name, uint64_t data_buffer_size) " (%s) data buffer size 0x%"PRIx64
-vfio_state_pending_exact(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t stopcopy_size) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" stopcopy size 0x%"PRIx64
+vfio_state_pending_estimate(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" precopy initial size 0x%"PRIx64" precopy dirty size 0x%"PRIx64
+vfio_state_pending_exact(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t stopcopy_size, uint64_t precopy_init_size, uint64_t precopy_dirty_size) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" stopcopy size 0x%"PRIx64" precopy initial size 0x%"PRIx64" precopy dirty size 0x%"PRIx64
 vfio_vmstate_change(const char *name, int running, const char *reason, const char *dev_state) " (%s) running %d reason %s device state %s"
-- 
2.41.0

[PULL 08/16] vfio/migration: Add support for switchover ack capability

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Loading of a VFIO device's data can take a substantial amount of time as
the device may need to allocate resources, prepare internal data
structures, etc. This can increase migration downtime, especially for
VFIO devices with a lot of resources.

To solve this, VFIO migration uAPI defines "initial bytes" as part of
its precopy data stream. Initial bytes can be used in various ways to
improve VFIO migration performance. For example, it can be used to
transfer device metadata to pre-allocate resources in the destination.
However, for this to work we need to make sure that all initial bytes
are sent and loaded in the destination before the source VM is stopped.

Use migration switchover ack capability to make sure a VFIO device's
initial bytes are sent and loaded in the destination before the source
stops the VM and attempts to complete the migration.
This can significantly reduce migration downtime for some devices.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Tested-by: YangHang Liu <yanghliu@redhat.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 docs/devel/vfio-migration.rst | 10 +++++++++
 include/hw/vfio/vfio-common.h |  1 +
 hw/vfio/migration.c           | 39 ++++++++++++++++++++++++++++++++++-
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/docs/devel/vfio-migration.rst b/docs/devel/vfio-migration.rst
index e896b2a6734b..b433cb5bb2c8 100644
--- a/docs/devel/vfio-migration.rst
+++ b/docs/devel/vfio-migration.rst
@@ -16,6 +16,13 @@ helps to reduce the total downtime of the VM. VFIO devices opt-in to pre-copy
 support by reporting the VFIO_MIGRATION_PRE_COPY flag in the
 VFIO_DEVICE_FEATURE_MIGRATION ioctl.
 
+When pre-copy is supported, it's possible to further reduce downtime by
+enabling "switchover-ack" migration capability.
+VFIO migration uAPI defines "initial bytes" as part of its pre-copy data stream
+and recommends that the initial bytes are sent and loaded in the destination
+before stopping the source VM. Enabling this migration capability will
+guarantee that and thus, can potentially reduce downtime even further.
+
 Note that currently VFIO migration is supported only for a single device. This
 is due to VFIO migration's lack of P2P support. However, P2P support is planned
 to be added later on.
@@ -45,6 +52,9 @@ VFIO implements the device hooks for the iterative approach as follows:
 * A ``save_live_iterate`` function that reads the VFIO device's data from the
   vendor driver during iterative pre-copy phase.
 
+* A ``switchover_ack_needed`` function that checks if the VFIO device uses
+  "switchover-ack" migration capability when this capability is enabled.
+
 * A ``save_state`` function to save the device config space if it is present.
 
 * A ``save_live_complete_precopy`` function that sets the VFIO device in
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 1db901c1941f..3dc5f2104c86 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -69,6 +69,7 @@ typedef struct VFIOMigration {
     uint64_t mig_flags;
     uint64_t precopy_init_size;
     uint64_t precopy_dirty_size;
+    bool initial_data_sent;
 } VFIOMigration;
 
 typedef struct VFIOAddressSpace {
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index d8f6a22ae14e..acbf0bb7ab3c 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -18,6 +18,8 @@
 #include "sysemu/runstate.h"
 #include "hw/vfio/vfio-common.h"
 #include "migration/migration.h"
+#include "migration/options.h"
+#include "migration/savevm.h"
 #include "migration/vmstate.h"
 #include "migration/qemu-file.h"
 #include "migration/register.h"
@@ -45,6 +47,7 @@
 #define VFIO_MIG_FLAG_DEV_CONFIG_STATE  (0xffffffffef100002ULL)
 #define VFIO_MIG_FLAG_DEV_SETUP_STATE   (0xffffffffef100003ULL)
 #define VFIO_MIG_FLAG_DEV_DATA_STATE    (0xffffffffef100004ULL)
+#define VFIO_MIG_FLAG_DEV_INIT_DATA_SENT (0xffffffffef100005ULL)
 
 /*
  * This is an arbitrary size based on migration of mlx5 devices, where typically
@@ -384,6 +387,7 @@ static void vfio_save_cleanup(void *opaque)
     migration->data_buffer = NULL;
     migration->precopy_init_size = 0;
     migration->precopy_dirty_size = 0;
+    migration->initial_data_sent = false;
     vfio_migration_cleanup(vbasedev);
     trace_vfio_save_cleanup(vbasedev->name);
 }
@@ -457,10 +461,17 @@ static int vfio_save_iterate(QEMUFile *f, void *opaque)
     if (data_size < 0) {
         return data_size;
     }
-    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
 
     vfio_update_estimated_pending_data(migration, data_size);
 
+    if (migrate_switchover_ack() && !migration->precopy_init_size &&
+        !migration->initial_data_sent) {
+        qemu_put_be64(f, VFIO_MIG_FLAG_DEV_INIT_DATA_SENT);
+        migration->initial_data_sent = true;
+    } else {
+        qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+    }
+
     trace_vfio_save_iterate(vbasedev->name, migration->precopy_init_size,
                             migration->precopy_dirty_size);
 
@@ -579,6 +590,24 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int version_id)
             }
             break;
         }
+        case VFIO_MIG_FLAG_DEV_INIT_DATA_SENT:
+        {
+            if (!vfio_precopy_supported(vbasedev) ||
+                !migrate_switchover_ack()) {
+                error_report("%s: Received INIT_DATA_SENT but switchover ack "
+                             "is not used", vbasedev->name);
+                return -EINVAL;
+            }
+
+            ret = qemu_loadvm_approve_switchover();
+            if (ret) {
+                error_report(
+                    "%s: qemu_loadvm_approve_switchover failed, err=%d (%s)",
+                    vbasedev->name, ret, strerror(-ret));
+            }
+
+            return ret;
+        }
         default:
             error_report("%s: Unknown tag 0x%"PRIx64, vbasedev->name, data);
             return -EINVAL;
@@ -593,6 +622,13 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int version_id)
     return ret;
 }
 
+static bool vfio_switchover_ack_needed(void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+
+    return vfio_precopy_supported(vbasedev);
+}
+
 static const SaveVMHandlers savevm_vfio_handlers = {
     .save_setup = vfio_save_setup,
     .save_cleanup = vfio_save_cleanup,
@@ -605,6 +641,7 @@ static const SaveVMHandlers savevm_vfio_handlers = {
     .load_setup = vfio_load_setup,
     .load_cleanup = vfio_load_cleanup,
     .load_state = vfio_load_state,
+    .switchover_ack_needed = vfio_switchover_ack_needed,
 };
 
 /* ---------------------------------------------------------------------- */
-- 
2.41.0

[PULL 09/16] vfio: Implement a common device info helper

[Cédric Le Goater]

From: Alex Williamson <alex.williamson@redhat.com>

A common helper implementing the realloc algorithm for handling
capabilities.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Robin Voetter <robin@streamhpc.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/hw/vfio/vfio-common.h |  1 +
 hw/s390x/s390-pci-vfio.c      | 37 ++++------------------------
 hw/vfio/common.c              | 46 ++++++++++++++++++++++++++---------
 3 files changed, 41 insertions(+), 43 deletions(-)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 3dc5f2104c86..6d1b8487c374 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -216,6 +216,7 @@ void vfio_region_finalize(VFIORegion *region);
 void vfio_reset_handler(void *opaque);
 VFIOGroup *vfio_get_group(int groupid, AddressSpace *as, Error **errp);
 void vfio_put_group(VFIOGroup *group);
+struct vfio_device_info *vfio_get_device_info(int fd);
 int vfio_get_device(VFIOGroup *group, const char *name,
                     VFIODevice *vbasedev, Error **errp);
 
diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
index f51190d4662f..59a2e03873bd 100644
--- a/hw/s390x/s390-pci-vfio.c
+++ b/hw/s390x/s390-pci-vfio.c
@@ -289,38 +289,11 @@ static void s390_pci_read_pfip(S390PCIBusDevice *pbdev,
     memcpy(pbdev->zpci_fn.pfip, cap->pfip, CLP_PFIP_NR_SEGMENTS);
 }
 
-static struct vfio_device_info *get_device_info(S390PCIBusDevice *pbdev,
-                                                uint32_t argsz)
+static struct vfio_device_info *get_device_info(S390PCIBusDevice *pbdev)
 {
-    struct vfio_device_info *info = g_malloc0(argsz);
-    VFIOPCIDevice *vfio_pci;
-    int fd;
+    VFIOPCIDevice *vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
 
-    vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
-    fd = vfio_pci->vbasedev.fd;
-
-    /*
-     * If the specified argsz is not large enough to contain all capabilities
-     * it will be updated upon return from the ioctl.  Retry until we have
-     * a big enough buffer to hold the entire capability chain.  On error,
-     * just exit and rely on CLP defaults.
-     */
-retry:
-    info->argsz = argsz;
-
-    if (ioctl(fd, VFIO_DEVICE_GET_INFO, info)) {
-        trace_s390_pci_clp_dev_info(vfio_pci->vbasedev.name);
-        g_free(info);
-        return NULL;
-    }
-
-    if (info->argsz > argsz) {
-        argsz = info->argsz;
-        info = g_realloc(info, argsz);
-        goto retry;
-    }
-
-    return info;
+    return vfio_get_device_info(vfio_pci->vbasedev.fd);
 }
 
 /*
@@ -335,7 +308,7 @@ bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh)
 
     assert(fh);
 
-    info = get_device_info(pbdev, sizeof(*info));
+    info = get_device_info(pbdev);
     if (!info) {
         return false;
     }
@@ -356,7 +329,7 @@ void s390_pci_get_clp_info(S390PCIBusDevice *pbdev)
 {
     g_autofree struct vfio_device_info *info = NULL;
 
-    info = get_device_info(pbdev, sizeof(*info));
+    info = get_device_info(pbdev);
     if (!info) {
         return;
     }
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 25801de173c4..28ec9e999c09 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -2846,11 +2846,35 @@ void vfio_put_group(VFIOGroup *group)
     }
 }
 
+struct vfio_device_info *vfio_get_device_info(int fd)
+{
+    struct vfio_device_info *info;
+    uint32_t argsz = sizeof(*info);
+
+    info = g_malloc0(argsz);
+
+retry:
+    info->argsz = argsz;
+
+    if (ioctl(fd, VFIO_DEVICE_GET_INFO, info)) {
+        g_free(info);
+        return NULL;
+    }
+
+    if (info->argsz > argsz) {
+        argsz = info->argsz;
+        info = g_realloc(info, argsz);
+        goto retry;
+    }
+
+    return info;
+}
+
 int vfio_get_device(VFIOGroup *group, const char *name,
                     VFIODevice *vbasedev, Error **errp)
 {
-    struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
-    int ret, fd;
+    g_autofree struct vfio_device_info *info = NULL;
+    int fd;
 
     fd = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name);
     if (fd < 0) {
@@ -2862,11 +2886,11 @@ int vfio_get_device(VFIOGroup *group, const char *name,
         return fd;
     }
 
-    ret = ioctl(fd, VFIO_DEVICE_GET_INFO, &dev_info);
-    if (ret) {
+    info = vfio_get_device_info(fd);
+    if (!info) {
         error_setg_errno(errp, errno, "error getting device info");
         close(fd);
-        return ret;
+        return -1;
     }
 
     /*
@@ -2894,14 +2918,14 @@ int vfio_get_device(VFIOGroup *group, const char *name,
     vbasedev->group = group;
     QLIST_INSERT_HEAD(&group->device_list, vbasedev, next);
 
-    vbasedev->num_irqs = dev_info.num_irqs;
-    vbasedev->num_regions = dev_info.num_regions;
-    vbasedev->flags = dev_info.flags;
+    vbasedev->num_irqs = info->num_irqs;
+    vbasedev->num_regions = info->num_regions;
+    vbasedev->flags = info->flags;
+
+    trace_vfio_get_device(name, info->flags, info->num_regions, info->num_irqs);
 
-    trace_vfio_get_device(name, dev_info.flags, dev_info.num_regions,
-                          dev_info.num_irqs);
+    vbasedev->reset_works = !!(info->flags & VFIO_DEVICE_FLAGS_RESET);
 
-    vbasedev->reset_works = !!(dev_info.flags & VFIO_DEVICE_FLAGS_RESET);
     return 0;
 }
 
-- 
2.41.0

[PULL 10/16] hw/vfio/pci-quirks: Support alternate offset for GPUDirect Cliques

[Cédric Le Goater]

From: Alex Williamson <alex.williamson@redhat.com>

NVIDIA Turing and newer GPUs implement the MSI-X capability at the offset
previously reserved for use by hypervisors to implement the GPUDirect
Cliques capability.  A revised specification provides an alternate
location.  Add a config space walk to the quirk to check for conflicts,
allowing us to fall back to the new location or generate an error at the
quirk setup rather than when the real conflicting capability is added
should there be no available location.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/pci-quirks.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index f0147a050aaa..0ed2fcd53152 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -1490,6 +1490,9 @@ void vfio_setup_resetfn_quirk(VFIOPCIDevice *vdev)
  * +---------------------------------+---------------------------------+
  *
  * https://lists.gnu.org/archive/html/qemu-devel/2017-08/pdfUda5iEpgOS.pdf
+ *
+ * Specification for Turning and later GPU architectures:
+ * https://lists.gnu.org/archive/html/qemu-devel/2023-06/pdf142OR4O4c2.pdf
  */
 static void get_nv_gpudirect_clique_id(Object *obj, Visitor *v,
                                        const char *name, void *opaque,
@@ -1530,7 +1533,9 @@ const PropertyInfo qdev_prop_nv_gpudirect_clique = {
 static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
 {
     PCIDevice *pdev = &vdev->pdev;
-    int ret, pos = 0xC8;
+    int ret, pos;
+    bool c8_conflict = false, d4_conflict = false;
+    uint8_t tmp;
 
     if (vdev->nv_gpudirect_clique == 0xFF) {
         return 0;
@@ -1547,6 +1552,40 @@ static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
         return -EINVAL;
     }
 
+    /*
+     * Per the updated specification above, it's recommended to use offset
+     * D4h for Turing and later GPU architectures due to a conflict of the
+     * MSI-X capability at C8h.  We don't know how to determine the GPU
+     * architecture, instead we walk the capability chain to mark conflicts
+     * and choose one or error based on the result.
+     *
+     * NB. Cap list head in pdev->config is already cleared, read from device.
+     */
+    ret = pread(vdev->vbasedev.fd, &tmp, 1,
+                vdev->config_offset + PCI_CAPABILITY_LIST);
+    if (ret != 1 || !tmp) {
+        error_setg(errp, "NVIDIA GPUDirect Clique ID: error getting cap list");
+        return -EINVAL;
+    }
+
+    do {
+        if (tmp == 0xC8) {
+            c8_conflict = true;
+        } else if (tmp == 0xD4) {
+            d4_conflict = true;
+        }
+        tmp = pdev->config[tmp + PCI_CAP_LIST_NEXT];
+    } while (tmp);
+
+    if (!c8_conflict) {
+        pos = 0xC8;
+    } else if (!d4_conflict) {
+        pos = 0xD4;
+    } else {
+        error_setg(errp, "NVIDIA GPUDirect Clique ID: invalid config space");
+        return -EINVAL;
+    }
+
     ret = pci_add_capability(pdev, PCI_CAP_ID_VNDR, pos, 8, errp);
     if (ret < 0) {
         error_prepend(errp, "Failed to add NVIDIA GPUDirect cap: ");
-- 
2.41.0

[PULL 11/16] vfio/pci: Call vfio_prepare_kvm_msi_virq_batch() in MSI retry path

[Cédric Le Goater]

From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

When vfio_enable_vectors() returns with less than requested nr_vectors
we retry with what kernel reported back. But the retry path doesn't
call vfio_prepare_kvm_msi_virq_batch() and this results in,

qemu-system-aarch64: vfio: Error: Failed to enable 4 MSI vectors, retry with 1
qemu-system-aarch64: ../hw/vfio/pci.c:602: vfio_commit_kvm_msi_virq_batch: Assertion `vdev->defer_kvm_irq_routing' failed

Fixes: dc580d51f7dd ("vfio: defer to commit kvm irq routing when enable msi/msix")
Reviewed-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 73874a94de12..8fb2c53a63bf 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -663,6 +663,8 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
 
     vfio_disable_interrupts(vdev);
 
+    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
+retry:
     /*
      * Setting vector notifiers needs to enable route for each vector.
      * Deferring to commit the KVM routes once rather than per vector
@@ -670,8 +672,6 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
      */
     vfio_prepare_kvm_msi_virq_batch(vdev);
 
-    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
-retry:
     vdev->msi_vectors = g_new0(VFIOMSIVector, vdev->nr_vectors);
 
     for (i = 0; i < vdev->nr_vectors; i++) {
-- 
2.41.0

Re: [PULL 11/16] vfio/pci: Call vfio_prepare_kvm_msi_virq_batch() in MSI retry path

[Michael Tokarev]

30.06.2023 08:22, Cédric Le Goater wrote:
> From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> 
> When vfio_enable_vectors() returns with less than requested nr_vectors
> we retry with what kernel reported back. But the retry path doesn't
> call vfio_prepare_kvm_msi_virq_batch() and this results in,
> 
> qemu-system-aarch64: vfio: Error: Failed to enable 4 MSI vectors, retry with 1
> qemu-system-aarch64: ../hw/vfio/pci.c:602: vfio_commit_kvm_msi_virq_batch: Assertion `vdev->defer_kvm_irq_routing' failed
> 
> Fixes: dc580d51f7dd ("vfio: defer to commit kvm irq routing when enable msi/msix")

Is it -stable material?

Thanks,

/mjt

[PULL 12/16] vfio/migration: Reset bytes_transferred properly

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

Currently, VFIO bytes_transferred is not reset properly:
1. bytes_transferred is not reset after a VM snapshot (so a migration
   following a snapshot will report incorrect value).
2. bytes_transferred is a single counter for all VFIO devices, however
   upon migration failure it is reset multiple times, by each VFIO
   device.

Fix it by introducing a new function vfio_reset_bytes_transferred() and
calling it during migration and snapshot start.

Remove existing bytes_transferred reset in VFIO migration state
notifier, which is not needed anymore.

Fixes: 3710586caa5d ("qapi: Add VFIO devices migration stats in Migration stats")
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/hw/vfio/vfio-common.h |  1 +
 migration/migration.h         |  1 +
 hw/vfio/migration.c           |  6 +++++-
 migration/migration.c         |  1 +
 migration/savevm.c            |  1 +
 migration/target.c            | 17 +++++++++++++++--
 6 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 6d1b8487c374..1d19c6f251c1 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -229,6 +229,7 @@ int vfio_block_multiple_devices_migration(Error **errp);
 void vfio_unblock_multiple_devices_migration(void);
 int vfio_block_giommu_migration(Error **errp);
 int64_t vfio_mig_bytes_transferred(void);
+void vfio_reset_bytes_transferred(void);
 
 #ifdef CONFIG_LINUX
 int vfio_get_region_info(VFIODevice *vbasedev, int index,
diff --git a/migration/migration.h b/migration/migration.h
index c859a0d35eb7..a80b22b703cd 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -514,6 +514,7 @@ bool migration_rate_limit(void);
 void migration_cancel(const Error *error);
 
 void populate_vfio_info(MigrationInfo *info);
+void reset_vfio_bytes_transferred(void);
 void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
 
 #endif
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index acbf0bb7ab3c..7cf143926ce9 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -697,7 +697,6 @@ static void vfio_migration_state_notifier(Notifier *notifier, void *data)
     case MIGRATION_STATUS_CANCELLING:
     case MIGRATION_STATUS_CANCELLED:
     case MIGRATION_STATUS_FAILED:
-        bytes_transferred = 0;
         /*
          * If setting the device in RUNNING state fails, the device should
          * be reset. To do so, use ERROR state as a recover state.
@@ -818,6 +817,11 @@ int64_t vfio_mig_bytes_transferred(void)
     return bytes_transferred;
 }
 
+void vfio_reset_bytes_transferred(void)
+{
+    bytes_transferred = 0;
+}
+
 int vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
 {
     int ret = -ENOTSUP;
diff --git a/migration/migration.c b/migration/migration.c
index 7653787f745d..096e8191d15c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1628,6 +1628,7 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
      */
     memset(&mig_stats, 0, sizeof(mig_stats));
     memset(&compression_counters, 0, sizeof(compression_counters));
+    reset_vfio_bytes_transferred();
 
     return true;
 }
diff --git a/migration/savevm.c b/migration/savevm.c
index cdf47939244d..95c2abf47c10 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1622,6 +1622,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
     migrate_init(ms);
     memset(&mig_stats, 0, sizeof(mig_stats));
     memset(&compression_counters, 0, sizeof(compression_counters));
+    reset_vfio_bytes_transferred();
     ms->to_dst_file = f;
 
     qemu_mutex_unlock_iothread();
diff --git a/migration/target.c b/migration/target.c
index 00ca007f9784..f39c9a8d8877 100644
--- a/migration/target.c
+++ b/migration/target.c
@@ -14,12 +14,25 @@
 #include "hw/vfio/vfio-common.h"
 #endif
 
+#ifdef CONFIG_VFIO
 void populate_vfio_info(MigrationInfo *info)
 {
-#ifdef CONFIG_VFIO
     if (vfio_mig_active()) {
         info->vfio = g_malloc0(sizeof(*info->vfio));
         info->vfio->transferred = vfio_mig_bytes_transferred();
     }
-#endif
 }
+
+void reset_vfio_bytes_transferred(void)
+{
+    vfio_reset_bytes_transferred();
+}
+#else
+void populate_vfio_info(MigrationInfo *info)
+{
+}
+
+void reset_vfio_bytes_transferred(void)
+{
+}
+#endif
-- 
2.41.0

[PULL 13/16] vfio/migration: Make VFIO migration non-experimental

[Cédric Le Goater]

From: Avihai Horon <avihaih@nvidia.com>

The major parts of VFIO migration are supported today in QEMU. This
includes basic VFIO migration, device dirty page tracking and precopy
support.

Thus, at this point in time, it seems appropriate to make VFIO migration
non-experimental: remove the x prefix from enable_migration property,
change it to ON_OFF_AUTO and let the default value be AUTO.

In addition, make the following adjustments:
1. When enable_migration is ON and migration is not supported, fail VFIO
   device realization.
2. When enable_migration is AUTO (i.e., not explicitly enabled), require
   device dirty tracking support. This is because device dirty tracking
   is currently the only method to do dirty page tracking, which is
   essential for migrating in a reasonable downtime. Setting
   enable_migration to ON will not require device dirty tracking.
3. Make migration error and blocker messages more elaborate.
4. Remove error prints in vfio_migration_query_flags().
5. Rename trace_vfio_migration_probe() to
   trace_vfio_migration_realize().

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 include/hw/vfio/vfio-common.h |  6 +--
 hw/vfio/common.c              | 16 ++++++-
 hw/vfio/migration.c           | 79 +++++++++++++++++++++++------------
 hw/vfio/pci.c                 |  4 +-
 hw/vfio/trace-events          |  2 +-
 5 files changed, 73 insertions(+), 34 deletions(-)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 1d19c6f251c1..93429b9abba0 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -139,7 +139,7 @@ typedef struct VFIODevice {
     bool needs_reset;
     bool no_mmap;
     bool ram_block_discard_allowed;
-    bool enable_migration;
+    OnOffAuto enable_migration;
     VFIODeviceOps *ops;
     unsigned int num_irqs;
     unsigned int num_regions;
@@ -225,9 +225,9 @@ typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
 extern VFIOGroupList vfio_group_list;
 
 bool vfio_mig_active(void);
-int vfio_block_multiple_devices_migration(Error **errp);
+int vfio_block_multiple_devices_migration(VFIODevice *vbasedev, Error **errp);
 void vfio_unblock_multiple_devices_migration(void);
-int vfio_block_giommu_migration(Error **errp);
+int vfio_block_giommu_migration(VFIODevice *vbasedev, Error **errp);
 int64_t vfio_mig_bytes_transferred(void);
 void vfio_reset_bytes_transferred(void);
 
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 28ec9e999c09..77e2ee0e5c6e 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -381,7 +381,7 @@ static unsigned int vfio_migratable_device_num(void)
     return device_num;
 }
 
-int vfio_block_multiple_devices_migration(Error **errp)
+int vfio_block_multiple_devices_migration(VFIODevice *vbasedev, Error **errp)
 {
     int ret;
 
@@ -390,6 +390,12 @@ int vfio_block_multiple_devices_migration(Error **errp)
         return 0;
     }
 
+    if (vbasedev->enable_migration == ON_OFF_AUTO_ON) {
+        error_setg(errp, "Migration is currently not supported with multiple "
+                         "VFIO devices");
+        return -EINVAL;
+    }
+
     error_setg(&multiple_devices_migration_blocker,
                "Migration is currently not supported with multiple "
                "VFIO devices");
@@ -427,7 +433,7 @@ static bool vfio_viommu_preset(void)
     return false;
 }
 
-int vfio_block_giommu_migration(Error **errp)
+int vfio_block_giommu_migration(VFIODevice *vbasedev, Error **errp)
 {
     int ret;
 
@@ -436,6 +442,12 @@ int vfio_block_giommu_migration(Error **errp)
         return 0;
     }
 
+    if (vbasedev->enable_migration == ON_OFF_AUTO_ON) {
+        error_setg(errp,
+                   "Migration is currently not supported with vIOMMU enabled");
+        return -EINVAL;
+    }
+
     error_setg(&giommu_migration_blocker,
                "Migration is currently not supported with vIOMMU enabled");
     ret = migrate_add_blocker(giommu_migration_blocker, errp);
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 7cf143926ce9..1db7d52ab2c1 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -724,14 +724,6 @@ static int vfio_migration_query_flags(VFIODevice *vbasedev, uint64_t *mig_flags)
     feature->argsz = sizeof(buf);
     feature->flags = VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_MIGRATION;
     if (ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature)) {
-        if (errno == ENOTTY) {
-            error_report("%s: VFIO migration is not supported in kernel",
-                         vbasedev->name);
-        } else {
-            error_report("%s: Failed to query VFIO migration support, err: %s",
-                         vbasedev->name, strerror(errno));
-        }
-
         return -errno;
     }
 
@@ -810,6 +802,27 @@ static int vfio_migration_init(VFIODevice *vbasedev)
     return 0;
 }
 
+static int vfio_block_migration(VFIODevice *vbasedev, Error *err, Error **errp)
+{
+    int ret;
+
+    if (vbasedev->enable_migration == ON_OFF_AUTO_ON) {
+        error_propagate(errp, err);
+        return -EINVAL;
+    }
+
+    vbasedev->migration_blocker = error_copy(err);
+    error_free(err);
+
+    ret = migrate_add_blocker(vbasedev->migration_blocker, errp);
+    if (ret < 0) {
+        error_free(vbasedev->migration_blocker);
+        vbasedev->migration_blocker = NULL;
+    }
+
+    return ret;
+}
+
 /* ---------------------------------------------------------------------- */
 
 int64_t vfio_mig_bytes_transferred(void)
@@ -824,40 +837,54 @@ void vfio_reset_bytes_transferred(void)
 
 int vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
 {
-    int ret = -ENOTSUP;
+    Error *err = NULL;
+    int ret;
 
-    if (!vbasedev->enable_migration) {
-        goto add_blocker;
+    if (vbasedev->enable_migration == ON_OFF_AUTO_OFF) {
+        error_setg(&err, "%s: Migration is disabled for VFIO device",
+                   vbasedev->name);
+        return vfio_block_migration(vbasedev, err, errp);
     }
 
     ret = vfio_migration_init(vbasedev);
     if (ret) {
-        goto add_blocker;
+        if (ret == -ENOTTY) {
+            error_setg(&err, "%s: VFIO migration is not supported in kernel",
+                       vbasedev->name);
+        } else {
+            error_setg(&err,
+                       "%s: Migration couldn't be initialized for VFIO device, "
+                       "err: %d (%s)",
+                       vbasedev->name, ret, strerror(-ret));
+        }
+
+        return vfio_block_migration(vbasedev, err, errp);
+    }
+
+    if (!vbasedev->dirty_pages_supported) {
+        if (vbasedev->enable_migration == ON_OFF_AUTO_AUTO) {
+            error_setg(&err,
+                       "%s: VFIO device doesn't support device dirty tracking",
+                       vbasedev->name);
+            return vfio_block_migration(vbasedev, err, errp);
+        }
+
+        warn_report("%s: VFIO device doesn't support device dirty tracking",
+                    vbasedev->name);
     }
 
-    ret = vfio_block_multiple_devices_migration(errp);
+    ret = vfio_block_multiple_devices_migration(vbasedev, errp);
     if (ret) {
         return ret;
     }
 
-    ret = vfio_block_giommu_migration(errp);
+    ret = vfio_block_giommu_migration(vbasedev, errp);
     if (ret) {
         return ret;
     }
 
-    trace_vfio_migration_probe(vbasedev->name);
+    trace_vfio_migration_realize(vbasedev->name);
     return 0;
-
-add_blocker:
-    error_setg(&vbasedev->migration_blocker,
-               "VFIO device doesn't support migration");
-
-    ret = migrate_add_blocker(vbasedev->migration_blocker, errp);
-    if (ret < 0) {
-        error_free(vbasedev->migration_blocker);
-        vbasedev->migration_blocker = NULL;
-    }
-    return ret;
 }
 
 void vfio_migration_exit(VFIODevice *vbasedev)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 8fb2c53a63bf..73e19a04b2bf 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3347,8 +3347,8 @@ static Property vfio_pci_dev_properties[] = {
                     VFIO_FEATURE_ENABLE_REQ_BIT, true),
     DEFINE_PROP_BIT("x-igd-opregion", VFIOPCIDevice, features,
                     VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false),
-    DEFINE_PROP_BOOL("x-enable-migration", VFIOPCIDevice,
-                     vbasedev.enable_migration, false),
+    DEFINE_PROP_ON_OFF_AUTO("enable-migration", VFIOPCIDevice,
+                            vbasedev.enable_migration, ON_OFF_AUTO_AUTO),
     DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false),
     DEFINE_PROP_BOOL("x-balloon-allowed", VFIOPCIDevice,
                      vbasedev.ram_block_discard_allowed, false),
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index e328d644d289..ee7509e68e4f 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -155,7 +155,7 @@ vfio_load_cleanup(const char *name) " (%s)"
 vfio_load_device_config_state(const char *name) " (%s)"
 vfio_load_state(const char *name, uint64_t data) " (%s) data 0x%"PRIx64
 vfio_load_state_device_data(const char *name, uint64_t data_size, int ret) " (%s) size 0x%"PRIx64" ret %d"
-vfio_migration_probe(const char *name) " (%s)"
+vfio_migration_realize(const char *name) " (%s)"
 vfio_migration_set_state(const char *name, const char *state) " (%s) state %s"
 vfio_migration_state_notifier(const char *name, const char *state) " (%s) state %s"
 vfio_save_block(const char *name, int data_size) " (%s) data_size %d"
-- 
2.41.0

[PULL 14/16] MAINTAINERS: Promote Cédric to VFIO co-maintainer

[Cédric Le Goater]

From: Alex Williamson <alex.williamson@redhat.com>

Cédric has stepped up involvement in vfio, reviewing and managing
patches, as well as pull requests.  This work deserves gratitude and
punishment with a promotion to co-maintainer ;)

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 MAINTAINERS | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index aba07722f64f..4feea49a6e95 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2051,7 +2051,7 @@ F: hw/usb/dev-serial.c
 
 VFIO
 M: Alex Williamson <alex.williamson@redhat.com>
-R: Cédric Le Goater <clg@redhat.com>
+M: Cédric Le Goater <clg@redhat.com>
 S: Supported
 F: hw/vfio/*
 F: include/hw/vfio/
-- 
2.41.0

[PULL 15/16] vfio/pci: Fix a segfault in vfio_realize

[Cédric Le Goater]

From: Zhenzhong Duan <zhenzhong.duan@intel.com>

The kvm irqchip notifier is only registered if the device supports
INTx, however it's unconditionally removed in vfio realize error
path. If the assigned device does not support INTx, this will cause
QEMU to crash when vfio realize fails. Change it to conditionally
remove the notifier only if the notify hook is setup.

Before fix:
(qemu) device_add vfio-pci,host=81:11.1,id=vfio1,bus=root1,xres=1
Connection closed by foreign host.

After fix:
(qemu) device_add vfio-pci,host=81:11.1,id=vfio1,bus=root1,xres=1
Error: vfio 0000:81:11.1: xres and yres properties require display=on
(qemu)

Fixes: c5478fea27ac ("vfio/pci: Respond to KVM irqchip change notifier")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/pci.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 73e19a04b2bf..48df517f79ee 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3221,7 +3221,9 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
 
 out_deregister:
     pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
-    kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
+    if (vdev->irqchip_change_notifier.notify) {
+        kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
+    }
 out_teardown:
     vfio_teardown_msi(vdev);
     vfio_bars_exit(vdev);
-- 
2.41.0

[PULL 16/16] vfio/pci: Free leaked timer in vfio_realize error path

[Cédric Le Goater]

From: Zhenzhong Duan <zhenzhong.duan@intel.com>

When vfio_realize fails, the mmap_timer used for INTx optimization
isn't freed. As this timer isn't activated yet, the potential impact
is just a piece of leaked memory.

Fixes: ea486926b07d ("vfio-pci: Update slow path INTx algorithm timer related")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 48df517f79ee..ab6645ba60af 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3224,6 +3224,9 @@ out_deregister:
     if (vdev->irqchip_change_notifier.notify) {
         kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
     }
+    if (vdev->intx.mmap_timer) {
+        timer_free(vdev->intx.mmap_timer);
+    }
 out_teardown:
     vfio_teardown_msi(vdev);
     vfio_bars_exit(vdev);
-- 
2.41.0

Re: [PULL 00/16] vfio queue

[Richard Henderson]

On 6/30/23 07:22, Cédric Le Goater wrote:
> The following changes since commit 4d541f63e90c81112c298cbb35ed53e9c79deb00:
> 
>    Merge tag 'for-upstream' ofhttps://gitlab.com/bonzini/qemu  into staging (2023-06-29 13:16:06 +0200)
> 
> are available in the Git repository at:
> 
>    https://github.com/legoater/qemu/  tags/pull-vfio-20230630
> 
> for you to fetch changes up to 0cc889c8826cefa5b80110d31a62273b56aa1832:
> 
>    vfio/pci: Free leaked timer in vfio_realize error path (2023-06-30 06:02:51 +0200)
> 
> ----------------------------------------------------------------
> vfio queue:
> 
> * migration: New switchover ack to reduce downtime
> * VFIO migration pre-copy support
> * Removal of the VFIO migration experimental flag
> * Alternate offset for GPUDirect Cliques
> * Misc fixes

Applied, thanks.  Please update https://wiki.qemu.org/ChangeLog/8.1 as appropriate.


r~