[Qemu-devel] [PATCH 5/5] vfio/migration: support device memory capability

[Yan Zhao]

If a device has device memory capability, save/load data from device memory
in pre-copy and stop-and-copy phases.

LOGGING state is set for device memory for dirty page logging:
in LOGGING state, get device memory returns whole device memory snapshot;
outside LOGGING state, get device memory returns dirty data since last get
operation.

Usually, device memory is very big, qemu needs to chunk it into several
pieces each with size of device memory region.

Signed-off-by: Yan Zhao <address@hidden>
Signed-off-by: Kirti Wankhede <address@hidden>
---
 hw/vfio/migration.c | 235 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 hw/vfio/pci.h       |   1 +
 2 files changed, 231 insertions(+), 5 deletions(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 16d6395..f1e9309 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -203,6 +203,201 @@ static int vfio_load_data_device_config(VFIOPCIDevice 
*vdev,
     return 0;
 }
 
+static int vfio_get_device_memory_size(VFIOPCIDevice *vdev)
+{
+    VFIODevice *vbasedev = &vdev->vbasedev;
+    VFIORegion *region_ctl =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_CTL];
+    uint64_t len;
+    int sz;
+
+    sz = sizeof(len);
+    if (pread(vbasedev->fd, &len, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.size))
+            != sz) {
+        error_report("vfio: Failed to get length of device memory");
+        return -1;
+    }
+    vdev->migration->devmem_size = len;
+    return 0;
+}
+
+static int vfio_set_device_memory_size(VFIOPCIDevice *vdev, uint64_t size)
+{
+    VFIODevice *vbasedev = &vdev->vbasedev;
+    VFIORegion *region_ctl =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_CTL];
+    int sz;
+
+    sz = sizeof(size);
+    if (pwrite(vbasedev->fd, &size, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.size))
+            != sz) {
+        error_report("vfio: Failed to set length of device comemory");
+        return -1;
+    }
+    vdev->migration->devmem_size = size;
+    return 0;
+}
+
+static
+int vfio_save_data_device_memory_chunk(VFIOPCIDevice *vdev, QEMUFile *f,
+                                    uint64_t pos, uint64_t len)
+{
+    VFIODevice *vbasedev = &vdev->vbasedev;
+    VFIORegion *region_ctl =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_CTL];
+    VFIORegion *region_devmem =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_DATA_DEVICE_MEMORY];
+    void *dest;
+    uint32_t sz;
+    uint8_t *buf = NULL;
+    uint32_t action = VFIO_DEVICE_DATA_ACTION_GET_BUFFER;
+
+    if (len > region_devmem->size) {
+        return -1;
+    }
+
+    sz = sizeof(pos);
+    if (pwrite(vbasedev->fd, &pos, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.pos))
+            != sz) {
+        error_report("vfio: Failed to set save buffer pos");
+        return -1;
+    }
+    sz = sizeof(action);
+    if (pwrite(vbasedev->fd, &action, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.action))
+            != sz) {
+        error_report("vfio: Failed to set save buffer action");
+        return -1;
+    }
+
+    if (!vfio_device_state_region_mmaped(region_devmem)) {
+        buf = g_malloc(len);
+        if (buf == NULL) {
+            error_report("vfio: Failed to allocate memory for migrate");
+            return -1;
+        }
+        if (pread(vbasedev->fd, buf, len, region_devmem->fd_offset) != len) {
+            error_report("vfio: error load device memory buffer");
+            return -1;
+        }
+        qemu_put_be64(f, len);
+        qemu_put_be64(f, pos);
+        qemu_put_buffer(f, buf, len);
+        g_free(buf);
+    } else {
+        dest = region_devmem->mmaps[0].mmap;
+        qemu_put_be64(f, len);
+        qemu_put_be64(f, pos);
+        qemu_put_buffer(f, dest, len);
+    }
+    return 0;
+}
+
+static int vfio_save_data_device_memory(VFIOPCIDevice *vdev, QEMUFile *f)
+{
+    VFIORegion *region_devmem =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_DATA_DEVICE_MEMORY];
+    uint64_t total_len = vdev->migration->devmem_size;
+    uint64_t pos = 0;
+
+    qemu_put_be64(f, total_len);
+    while (pos < total_len) {
+        uint64_t len = region_devmem->size;
+
+        if (pos + len >= total_len) {
+            len = total_len - pos;
+        }
+        if (vfio_save_data_device_memory_chunk(vdev, f, pos, len)) {
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static
+int vfio_load_data_device_memory_chunk(VFIOPCIDevice *vdev, QEMUFile *f,
+                                uint64_t pos, uint64_t len)
+{
+    VFIODevice *vbasedev = &vdev->vbasedev;
+    VFIORegion *region_ctl =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_CTL];
+    VFIORegion *region_devmem =
+        &vdev->migration->region[VFIO_DEVSTATE_REGION_DATA_DEVICE_MEMORY];
+
+    void *dest;
+    uint32_t sz;
+    uint8_t *buf = NULL;
+    uint32_t action = VFIO_DEVICE_DATA_ACTION_SET_BUFFER;
+
+    if (len > region_devmem->size) {
+        return -1;
+    }
+
+    sz = sizeof(pos);
+    if (pwrite(vbasedev->fd, &pos, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.pos))
+            != sz) {
+        error_report("vfio: Failed to set device memory buffer pos");
+        return -1;
+    }
+    if (!vfio_device_state_region_mmaped(region_devmem)) {
+        buf = g_malloc(len);
+        if (buf == NULL) {
+            error_report("vfio: Failed to allocate memory for migrate");
+            return -1;
+        }
+        qemu_get_buffer(f, buf, len);
+        if (pwrite(vbasedev->fd, buf, len,
+                    region_devmem->fd_offset) != len) {
+            error_report("vfio: Failed to load devie memory buffer");
+            return -1;
+        }
+        g_free(buf);
+    } else {
+        dest = region_devmem->mmaps[0].mmap;
+        qemu_get_buffer(f, dest, len);
+    }
+
+    sz = sizeof(action);
+    if (pwrite(vbasedev->fd, &action, sz,
+                region_ctl->fd_offset +
+                offsetof(struct vfio_device_state_ctl, device_memory.action))
+            != sz) {
+        error_report("vfio: Failed to set load device memory buffer action");
+        return -1;
+    }
+
+    return 0;
+
+}
+
+static int vfio_load_data_device_memory(VFIOPCIDevice *vdev,
+                        QEMUFile *f, uint64_t total_len)
+{
+    uint64_t pos = 0, len = 0;
+
+    vfio_set_device_memory_size(vdev, total_len);
+
+    while (pos + len < total_len) {
+        len = qemu_get_be64(f);
+        pos = qemu_get_be64(f);
+
+        vfio_load_data_device_memory_chunk(vdev, f, pos, len);
+    }
+
+    return 0;
+}
+
+
 static int vfio_set_dirty_page_bitmap_chunk(VFIOPCIDevice *vdev,
         uint64_t start_addr, uint64_t page_nr)
 {
@@ -377,6 +572,10 @@ static void vfio_save_live_pending(QEMUFile *f, void 
*opaque,
         return;
     }
 
+    /* get dirty data size of device memory */
+    vfio_get_device_memory_size(vdev);
+
+    *res_precopy_only += vdev->migration->devmem_size;
     return;
 }
 
@@ -388,7 +587,9 @@ static int vfio_save_iterate(QEMUFile *f, void *opaque)
         return 0;
     }
 
-    return 0;
+    qemu_put_byte(f, VFIO_SAVE_FLAG_DEVMEMORY);
+    /* get dirty data of device memory */
+    return vfio_save_data_device_memory(vdev, f);
 }
 
 static void vfio_pci_load_config(VFIOPCIDevice *vdev, QEMUFile *f)
@@ -458,6 +659,10 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int 
version_id)
             len = qemu_get_be64(f);
             vfio_load_data_device_config(vdev, f, len);
             break;
+        case VFIO_SAVE_FLAG_DEVMEMORY:
+            len = qemu_get_be64(f);
+            vfio_load_data_device_memory(vdev, f, len);
+            break;
         default:
             ret = -EINVAL;
         }
@@ -503,6 +708,13 @@ static int vfio_save_complete_precopy(QEMUFile *f, void 
*opaque)
     VFIOPCIDevice *vdev = opaque;
     int rc = 0;
 
+    if (vfio_device_data_cap_device_memory(vdev)) {
+        qemu_put_byte(f, VFIO_SAVE_FLAG_DEVMEMORY | VFIO_SAVE_FLAG_CONTINUE);
+        /* get dirty data of device memory */
+        vfio_get_device_memory_size(vdev);
+        rc = vfio_save_data_device_memory(vdev, f);
+    }
+
     qemu_put_byte(f, VFIO_SAVE_FLAG_PCI | VFIO_SAVE_FLAG_CONTINUE);
     vfio_pci_save_config(vdev, f);
 
@@ -515,12 +727,22 @@ static int vfio_save_complete_precopy(QEMUFile *f, void 
*opaque)
 
 static int vfio_save_setup(QEMUFile *f, void *opaque)
 {
+    int rc = 0;
     VFIOPCIDevice *vdev = opaque;
-    qemu_put_byte(f, VFIO_SAVE_FLAG_SETUP);
+
+    if (vfio_device_data_cap_device_memory(vdev)) {
+        qemu_put_byte(f, VFIO_SAVE_FLAG_SETUP | VFIO_SAVE_FLAG_CONTINUE);
+        qemu_put_byte(f, VFIO_SAVE_FLAG_DEVMEMORY);
+        /* get whole snapshot of device memory */
+        vfio_get_device_memory_size(vdev);
+        rc = vfio_save_data_device_memory(vdev, f);
+    } else {
+        qemu_put_byte(f, VFIO_SAVE_FLAG_SETUP);
+    }
 
     vfio_set_device_state(vdev, VFIO_DEVICE_STATE_RUNNING |
             VFIO_DEVICE_STATE_LOGGING);
-    return 0;
+    return rc;
 }
 
 static int vfio_load_setup(QEMUFile *f, void *opaque)
@@ -576,8 +798,11 @@ int vfio_migration_init(VFIOPCIDevice *vdev, Error **errp)
         goto error;
     }
 
-    if (vfio_device_data_cap_device_memory(vdev)) {
-        error_report("No suppport of data cap device memory Yet");
+    if (vfio_device_data_cap_device_memory(vdev) &&
+            vfio_device_state_region_setup(vdev,
+              
&vdev->migration->region[VFIO_DEVSTATE_REGION_DATA_DEVICE_MEMORY],
+              VFIO_REGION_SUBTYPE_DEVICE_STATE_DATA_MEMORY,
+              "device-state-data-device-memory")) {
         goto error;
     }
 
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 4b7b1bb..a2cc64b 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -69,6 +69,7 @@ typedef struct VFIOMigration {
     uint32_t data_caps;
     uint32_t device_state;
     uint64_t devconfig_size;
+    uint64_t devmem_size;
     VMChangeStateEntry *vm_state;
 } VFIOMigration;
 
-- 
2.7.4