[Qemu-devel] [PATCH v8 06/13] vfio: Add VM state change handler to know state of VM

[Kirti Wankhede <kwankhede@nvidia.com>]

VM state change handler gets called on change in VM's state. This is used to set
VFIO device state to _RUNNING.
VM state change handler, migration state change handler and log_sync listener
are called asynchronously, which sometimes lead to data corruption in migration
region. Initialised mutex that is used to serialize operations on migration data
region during saving state.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 hw/vfio/migration.c           | 67 +++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/trace-events          |  2 ++
 include/hw/vfio/vfio-common.h |  4 +++
 3 files changed, 73 insertions(+)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index a1feeb7e1a5a..83057d909d49 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -10,6 +10,7 @@
 #include "qemu/osdep.h"
 #include <linux/vfio.h>
 
+#include "sysemu/runstate.h"
 #include "hw/vfio/vfio-common.h"
 #include "cpu.h"
 #include "migration/migration.h"
@@ -74,6 +75,65 @@ err:
     return ret;
 }
 
+static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t set_flags,
+                                    uint32_t clear_flags)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint32_t device_state;
+    int ret = 0;
+
+    /* same flags should not be set or clear */
+    assert(!(set_flags & clear_flags));
+
+    device_state = (vbasedev->device_state | set_flags) & ~clear_flags;
+
+    if ((device_state & VFIO_DEVICE_STATE_MASK) == VFIO_DEVICE_STATE_INVALID) {
+        return -EINVAL;
+    }
+
+    ret = pwrite(vbasedev->fd, &device_state, sizeof(device_state),
+                 region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                              device_state));
+    if (ret < 0) {
+        error_report("%s: Failed to set device state %d %s",
+                     vbasedev->name, ret, strerror(errno));
+        return ret;
+    }
+
+    vbasedev->device_state = device_state;
+    trace_vfio_migration_set_state(vbasedev->name, device_state);
+    return 0;
+}
+
+static void vfio_vmstate_change(void *opaque, int running, RunState state)
+{
+    VFIODevice *vbasedev = opaque;
+
+    if ((vbasedev->vm_running != running)) {
+        int ret;
+        uint32_t set_flags = 0, clear_flags = 0;
+
+        if (running) {
+            set_flags = VFIO_DEVICE_STATE_RUNNING;
+            if (vbasedev->device_state & VFIO_DEVICE_STATE_RESUMING) {
+                clear_flags = VFIO_DEVICE_STATE_RESUMING;
+            }
+        } else {
+            clear_flags = VFIO_DEVICE_STATE_RUNNING;
+        }
+
+        ret = vfio_migration_set_state(vbasedev, set_flags, clear_flags);
+        if (ret) {
+            error_report("%s: Failed to set device state 0x%x",
+                         vbasedev->name, set_flags & ~clear_flags);
+        }
+        vbasedev->vm_running = running;
+        trace_vfio_vmstate_change(vbasedev->name, running, RunState_str(state),
+                                  set_flags & ~clear_flags);
+    }
+}
+
 static int vfio_migration_init(VFIODevice *vbasedev,
                                struct vfio_region_info *info)
 {
@@ -89,6 +149,9 @@ static int vfio_migration_init(VFIODevice *vbasedev,
         return ret;
     }
 
+    vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change,
+                                                          vbasedev);
+
     return 0;
 }
 
@@ -127,6 +190,10 @@ add_blocker:
 
 void vfio_migration_finalize(VFIODevice *vbasedev)
 {
+    if (vbasedev->vm_state) {
+        qemu_del_vm_change_state_handler(vbasedev->vm_state);
+    }
+
     if (vbasedev->migration_blocker) {
         migrate_del_blocker(vbasedev->migration_blocker);
         error_free(vbasedev->migration_blocker);
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 191a726a1312..3d15bacd031a 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -146,3 +146,5 @@ vfio_display_edid_write_error(void) ""
 
 # migration.c
 vfio_migration_probe(char *name, uint32_t index) " (%s) Region %d"
+vfio_migration_set_state(char *name, uint32_t state) " (%s) state %d"
+vfio_vmstate_change(char *name, int running, const char *reason, uint32_t dev_state) " (%s) running %d reason %s device state %d"
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index f80e04e26e1f..15be0358845b 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -29,6 +29,7 @@
 #ifdef CONFIG_LINUX
 #include <linux/vfio.h>
 #endif
+#include "sysemu/sysemu.h"
 
 #define VFIO_MSG_PREFIX "vfio %s: "
 
@@ -121,6 +122,9 @@ typedef struct VFIODevice {
     unsigned int flags;
     VFIOMigration *migration;
     Error *migration_blocker;
+    uint32_t device_state;
+    VMChangeStateEntry *vm_state;
+    int vm_running;
 } VFIODevice;
 
 struct VFIODeviceOps {
-- 
2.7.0