[V1,14/26] migration: close kvm after cpr

Commit Message

Steven Sistare Jan. 29, 2025, 2:43 p.m. UTC

cpr-transfer breaks vfio network connectivity to and from the guest, and
the host system log shows:
  irq bypass consumer (token 00000000a03c32e5) registration fails: -16
which is EBUSY.  This occurs because KVM descriptors are still open in
the old QEMU process.  Close them.

Signed-off-by: Steve Sistare <[e-mail]>
---
 accel/kvm/kvm-all.c           | 20 ++++++++++++++++++++
 hw/vfio/common.c              |  8 ++++++++
 include/hw/vfio/vfio-common.h |  1 +
 include/migration/cpr.h       |  2 ++
 include/system/kvm.h          |  1 +
 migration/cpr-transfer.c      | 18 ++++++++++++++++++
 migration/cpr.c               |  8 ++++++++
 migration/migration.c         |  1 +
 8 files changed, 59 insertions(+)

Patch

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index c65b790..f4e341f 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -595,6 +595,26 @@  err:
     return ret;
 }
 
+void kvm_close(void)
+{
+    CPUState *cpu;
+
+    CPU_FOREACH(cpu) {
+        cpu_remove_sync(cpu);
+        close(cpu->kvm_fd);
+        cpu->kvm_fd = -1;
+        close(cpu->kvm_vcpu_stats_fd);
+        cpu->kvm_vcpu_stats_fd = -1;
+    }
+
+    if (kvm_state && kvm_state->fd != -1) {
+        close(kvm_state->vmfd);
+        kvm_state->vmfd = -1;
+        close(kvm_state->fd);
+        kvm_state->fd = -1;
+    }
+}
+
 /*
  * dirty pages logging control
  */
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index c8ee71a..db0498e 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1511,6 +1511,14 @@  int vfio_kvm_device_del_fd(int fd, Error **errp)
     return 0;
 }
 
+void vfio_kvm_device_close(void)
+{
+    if (vfio_kvm_device_fd != -1) {
+        close(vfio_kvm_device_fd);
+        vfio_kvm_device_fd = -1;
+    }
+}
+
 VFIOAddressSpace *vfio_get_address_space(AddressSpace *as)
 {
     VFIOAddressSpace *space;
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 8a4a658..5a89aca 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -262,6 +262,7 @@  void vfio_detach_device(VFIODevice *vbasedev);
 
 int vfio_kvm_device_add_fd(int fd, Error **errp);
 int vfio_kvm_device_del_fd(int fd, Error **errp);
+void vfio_kvm_device_close(void);
 
 bool vfio_cpr_register_container(VFIOContainerBase *bcontainer, Error **errp);
 void vfio_cpr_unregister_container(VFIOContainerBase *bcontainer);
diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index faeb0cc..e8f4aba 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -29,7 +29,9 @@  void cpr_state_close(void);
 struct QIOChannel *cpr_state_ioc(void);
 
 bool cpr_needed_for_reuse(void *opaque);
+void cpr_kvm_close(void);
 
+void cpr_transfer_init(void);
 QEMUFile *cpr_transfer_output(MigrationChannel *channel, Error **errp);
 QEMUFile *cpr_transfer_input(MigrationChannel *channel, Error **errp);
 
diff --git a/include/system/kvm.h b/include/system/kvm.h
index ab17c09..ad5c55e 100644
--- a/include/system/kvm.h
+++ b/include/system/kvm.h
@@ -194,6 +194,7 @@  bool kvm_has_sync_mmu(void);
 int kvm_has_vcpu_events(void);
 int kvm_max_nested_state_length(void);
 int kvm_has_gsi_routing(void);
+void kvm_close(void);
 
 /**
  * kvm_arm_supports_user_irq
diff --git a/migration/cpr-transfer.c b/migration/cpr-transfer.c
index e1f1403..396558f 100644
--- a/migration/cpr-transfer.c
+++ b/migration/cpr-transfer.c
@@ -17,6 +17,24 @@ 
 #include "migration/vmstate.h"
 #include "trace.h"
 
+static int cpr_transfer_notifier(NotifierWithReturn *notifier,
+                                 MigrationEvent *e,
+                                 Error **errp)
+{
+    if (e->type == MIG_EVENT_PRECOPY_DONE) {
+        cpr_kvm_close();
+    }
+    return 0;
+}
+
+void cpr_transfer_init(void)
+{
+    static NotifierWithReturn notifier;
+
+    migration_add_notifier_mode(&notifier, cpr_transfer_notifier,
+                                MIG_MODE_CPR_TRANSFER);
+}
+
 QEMUFile *cpr_transfer_output(MigrationChannel *channel, Error **errp)
 {
     MigrationAddress *addr = channel->addr;
diff --git a/migration/cpr.c b/migration/cpr.c
index e3f27e9..86eb484 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -7,12 +7,14 @@ 
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
+#include "hw/vfio/vfio-common.h"
 #include "migration/cpr.h"
 #include "migration/misc.h"
 #include "migration/options.h"
 #include "migration/qemu-file.h"
 #include "migration/savevm.h"
 #include "migration/vmstate.h"
+#include "system/kvm.h"
 #include "system/runstate.h"
 #include "trace.h"
 
@@ -243,3 +245,9 @@  bool cpr_needed_for_reuse(void *opaque)
     MigMode mode = migrate_mode();
     return mode == MIG_MODE_CPR_TRANSFER;
 }
+
+void cpr_kvm_close(void)
+{
+    kvm_close();
+    vfio_kvm_device_close();
+}
diff --git a/migration/migration.c b/migration/migration.c
index 88b0991..7a69782 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -288,6 +288,7 @@  void migration_object_init(void)
 
     ram_mig_init();
     dirty_bitmap_mig_init();
+    cpr_transfer_init();
 
     /* Initialize cpu throttle timers */
     cpu_throttle_init();