[PATCH v27 08/17] vfio: Add save state functions to SaveVMHandlers

[Kirti Wankhede <kwankhede@nvidia.com>]

Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy
functions. These functions handles pre-copy and stop-and-copy phase.

In _SAVING|_RUNNING device state or pre-copy phase:
- read pending_bytes. If pending_bytes > 0, go through below steps.
- read data_offset - indicates kernel driver to write data to staging
  buffer.
- read data_size - amount of data in bytes written by vendor driver in
  migration region.
- read data_size bytes of data from data_offset in the migration region.
- Write data packet to file stream as below:
{VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data,
VFIO_MIG_FLAG_END_OF_STATE }

In _SAVING device state or stop-and-copy phase
a. read config space of device and save to migration file stream. This
   doesn't need to be from vendor driver. Any other special config state
   from driver can be saved as data in following iteration.
b. read pending_bytes. If pending_bytes > 0, go through below steps.
c. read data_offset - indicates kernel driver to write data to staging
   buffer.
d. read data_size - amount of data in bytes written by vendor driver in
   migration region.
e. read data_size bytes of data from data_offset in the migration region.
f. Write data packet as below:
   {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data}
g. iterate through steps b to f while (pending_bytes > 0)
h. Write {VFIO_MIG_FLAG_END_OF_STATE}

When data region is mapped, its user's responsibility to read data from
data_offset of data_size before moving to next steps.

Includes
Fix Reported-by: Zhi Wang <zhi.wang.linux@gmail.com>
https://www.mail-archive.com/qemu-devel@nongnu.org/msg743722.htm

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>

---
 hw/vfio/migration.c           | 276 ++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/trace-events          |   6 +
 include/hw/vfio/vfio-common.h |   1 +
 3 files changed, 283 insertions(+)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 2e1054bf7f43..5506cef15d88 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -148,6 +148,151 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask,
     return 0;
 }
 
+static void *get_data_section_size(VFIORegion *region, uint64_t data_offset,
+                                   uint64_t data_size, uint64_t *size)
+{
+    void *ptr = NULL;
+    uint64_t limit = 0;
+    int i;
+
+    if (!region->mmaps) {
+        if (size) {
+            *size = MIN(data_size, region->size - data_offset);
+        }
+        return ptr;
+    }
+
+    for (i = 0; i < region->nr_mmaps; i++) {
+        VFIOMmap *map = region->mmaps + i;
+
+        if ((data_offset >= map->offset) &&
+            (data_offset < map->offset + map->size)) {
+
+            /* check if data_offset is within sparse mmap areas */
+            ptr = map->mmap + data_offset - map->offset;
+            if (size) {
+                *size = MIN(data_size, map->offset + map->size - data_offset);
+            }
+            break;
+        } else if ((data_offset < map->offset) &&
+                   (!limit || limit > map->offset)) {
+            /*
+             * data_offset is not within sparse mmap areas, find size of
+             * non-mapped area. Check through all list since region->mmaps list
+             * is not sorted.
+             */
+            limit = map->offset;
+        }
+    }
+
+    if (!ptr && size) {
+        *size = limit ? MIN(data_size, limit - data_offset) : data_size;
+    }
+    return ptr;
+}
+
+static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev, uint64_t *size)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint64_t data_offset = 0, data_size = 0, sz;
+    int ret;
+
+    ret = vfio_mig_read(vbasedev, &data_offset, sizeof(data_offset),
+                      region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_offset));
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = vfio_mig_read(vbasedev, &data_size, sizeof(data_size),
+                        region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_size));
+    if (ret < 0) {
+        return ret;
+    }
+
+    trace_vfio_save_buffer(vbasedev->name, data_offset, data_size,
+                           migration->pending_bytes);
+
+    qemu_put_be64(f, data_size);
+    sz = data_size;
+
+    while (sz) {
+        void *buf;
+        uint64_t sec_size;
+        bool buf_allocated = false;
+
+        buf = get_data_section_size(region, data_offset, sz, &sec_size);
+
+        if (!buf) {
+            buf = g_try_malloc(sec_size);
+            if (!buf) {
+                error_report("%s: Error allocating buffer ", __func__);
+                return -ENOMEM;
+            }
+            buf_allocated = true;
+
+            ret = vfio_mig_read(vbasedev, buf, sec_size,
+                                region->fd_offset + data_offset);
+            if (ret < 0) {
+                g_free(buf);
+                return ret;
+            }
+        }
+
+        qemu_put_buffer(f, buf, sec_size);
+
+        if (buf_allocated) {
+            g_free(buf);
+        }
+        sz -= sec_size;
+        data_offset += sec_size;
+    }
+
+    ret = qemu_file_get_error(f);
+
+    if (!ret && size) {
+        *size = data_size;
+    }
+
+    return ret;
+}
+
+static int vfio_update_pending(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint64_t pending_bytes = 0;
+    int ret;
+
+    ret = vfio_mig_read(vbasedev, &pending_bytes, sizeof(pending_bytes),
+                    region->fd_offset + VFIO_MIG_STRUCT_OFFSET(pending_bytes));
+    if (ret < 0) {
+        migration->pending_bytes = 0;
+        return ret;
+    }
+
+    migration->pending_bytes = pending_bytes;
+    trace_vfio_update_pending(vbasedev->name, pending_bytes);
+    return 0;
+}
+
+static int vfio_save_device_config_state(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_STATE);
+
+    if (vbasedev->ops && vbasedev->ops->vfio_save_config) {
+        vbasedev->ops->vfio_save_config(vbasedev, f);
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    trace_vfio_save_device_config_state(vbasedev->name);
+
+    return qemu_file_get_error(f);
+}
+
 /* ---------------------------------------------------------------------- */
 
 static int vfio_save_setup(QEMUFile *f, void *opaque)
@@ -204,9 +349,140 @@ static void vfio_save_cleanup(void *opaque)
     trace_vfio_save_cleanup(vbasedev->name);
 }
 
+static void vfio_save_pending(QEMUFile *f, void *opaque,
+                              uint64_t threshold_size,
+                              uint64_t *res_precopy_only,
+                              uint64_t *res_compatible,
+                              uint64_t *res_postcopy_only)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret;
+
+    ret = vfio_update_pending(vbasedev);
+    if (ret) {
+        return;
+    }
+
+    *res_precopy_only += migration->pending_bytes;
+
+    trace_vfio_save_pending(vbasedev->name, *res_precopy_only,
+                            *res_postcopy_only, *res_compatible);
+}
+
+static int vfio_save_iterate(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    uint64_t data_size;
+    int ret;
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
+
+    if (migration->pending_bytes == 0) {
+        ret = vfio_update_pending(vbasedev);
+        if (ret) {
+            return ret;
+        }
+
+        if (migration->pending_bytes == 0) {
+            qemu_put_be64(f, 0);
+            qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+            /* indicates data finished, goto complete phase */
+            return 1;
+        }
+    }
+
+    ret = vfio_save_buffer(f, vbasedev, &data_size);
+    if (ret) {
+        error_report("%s: vfio_save_buffer failed %s", vbasedev->name,
+                     strerror(errno));
+        return ret;
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    /*
+     * Reset pending_bytes as .save_live_pending is not called during savevm or
+     * snapshot case, in such case vfio_update_pending() at the start of this
+     * function updates pending_bytes.
+     */
+    migration->pending_bytes = 0;
+    trace_vfio_save_iterate(vbasedev->name, data_size);
+    return 0;
+}
+
+static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    uint64_t data_size;
+    int ret;
+
+    ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_RUNNING,
+                                   VFIO_DEVICE_STATE_SAVING);
+    if (ret) {
+        error_report("%s: Failed to set state STOP and SAVING",
+                     vbasedev->name);
+        return ret;
+    }
+
+    ret = vfio_save_device_config_state(f, opaque);
+    if (ret) {
+        return ret;
+    }
+
+    ret = vfio_update_pending(vbasedev);
+    if (ret) {
+        return ret;
+    }
+
+    while (migration->pending_bytes > 0) {
+        qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
+        ret = vfio_save_buffer(f, vbasedev, &data_size);
+        if (ret < 0) {
+            error_report("%s: Failed to save buffer", vbasedev->name);
+            return ret;
+        }
+
+        if (data_size == 0) {
+            break;
+        }
+
+        ret = vfio_update_pending(vbasedev);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_SAVING, 0);
+    if (ret) {
+        error_report("%s: Failed to set state STOPPED", vbasedev->name);
+        return ret;
+    }
+
+    trace_vfio_save_complete_precopy(vbasedev->name);
+    return ret;
+}
+
 static SaveVMHandlers savevm_vfio_handlers = {
     .save_setup = vfio_save_setup,
     .save_cleanup = vfio_save_cleanup,
+    .save_live_pending = vfio_save_pending,
+    .save_live_iterate = vfio_save_iterate,
+    .save_live_complete_precopy = vfio_save_complete_precopy,
 };
 
 /* ---------------------------------------------------------------------- */
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index f148b5e828c1..9f5712dab1ea 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -153,3 +153,9 @@ vfio_vmstate_change(const char *name, int running, const char *reason, uint32_t
 vfio_migration_state_notifier(const char *name, const char *state) " (%s) state %s"
 vfio_save_setup(const char *name) " (%s)"
 vfio_save_cleanup(const char *name) " (%s)"
+vfio_save_buffer(const char *name, uint64_t data_offset, uint64_t data_size, uint64_t pending) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64" pending 0x%"PRIx64
+vfio_update_pending(const char *name, uint64_t pending) " (%s) pending 0x%"PRIx64
+vfio_save_device_config_state(const char *name) " (%s)"
+vfio_save_pending(const char *name, uint64_t precopy, uint64_t postcopy, uint64_t compatible) " (%s) precopy 0x%"PRIx64" postcopy 0x%"PRIx64" compatible 0x%"PRIx64
+vfio_save_iterate(const char *name, int data_size) " (%s) data_size %d"
+vfio_save_complete_precopy(const char *name) " (%s)"
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 2bd593ba38bb..f4ebdae013ad 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -65,6 +65,7 @@ typedef struct VFIOMigration {
     uint32_t device_state;
     int vm_running;
     Notifier migration_state;
+    uint64_t pending_bytes;
 } VFIOMigration;
 
 typedef struct VFIOAddressSpace {
-- 
2.7.0