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

[Zhao Yan]

On Tue, Feb 19, 2019 at 11:25:43AM +0000, Dr. David Alan Gilbert wrote:
> * Yan Zhao (address@hidden) wrote:
> > 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");
> 
> That's forgotten to g_free(buf)
>
Right, I'll correct that.

> > +            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");
> 
> Again, failed to free buf
> 
Right, I'll correct that.
> > +            return -1;
> > +        }
> > +        g_free(buf);
> > +    } else {
> > +        dest = region_devmem->mmaps[0].mmap;
> > +        qemu_get_buffer(f, dest, len);
> > +    }
> 
> You might want to use qemu_file_get_error(f)  before writing the data
> to the device, to check for the case of a read error on the migration
> stream that happened somewhere in the pevious qemu_get's
>

ok.

> > +    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);
> 
> Please check len/pos - always assume that the migration stream could
> be (maliciously or accidentally) corrupt.
>
ok.

> > +        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
> > 
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
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