Re: [Qemu-devel] [PATCH] vmstate: Add support for saving/loading bitmaps

[Igor Mitsyanko <i.mitsyanko@samsung.com>]

On 08/09/2012 03:54 PM, Peter Maydell wrote:
> Add support for saving/loading bitmap.h bitmaps in vmstate.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> This will be needed for saving/restoring the bitmap in sd.c which
> is introduced by Igor's latest patchset; the relevant VMSTATE line is:
>          VMSTATE_BITMAP(wp_groups, SDState, 1, wpgrps_size),
> (and you'll need to make wpgrps_size an int32_t, not uint32_t).
>
> Igor: I've only tested this fairly lightly, you'll probably want to
> do things like testing save on 32 bit and load on 64 bit and
> vice-versa.
>
>   savevm.c  |   41 +++++++++++++++++++++++++++++++++++++++++
>   vmstate.h |   13 +++++++++++++
>   2 files changed, 54 insertions(+)
>
> diff --git a/savevm.c b/savevm.c
> index 6e82b2d..0e2de97 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -86,6 +86,7 @@
>   #include "memory.h"
>   #include "qmp-commands.h"
>   #include "trace.h"
> +#include "bitops.h"
>   
>   #define SELF_ANNOUNCE_ROUNDS 5
>   
> @@ -1159,6 +1160,46 @@ const VMStateInfo vmstate_info_unused_buffer = {
>       .put  = put_unused_buffer,
>   };
>   
> +/* bitmaps (as defined by bitmap.h). Note that size here is the size
> + * of the bitmap in bits. The on-the-wire format of a bitmap is 64
> + * bit words with the bits in big endian order. The in-memory format
> + * is an array of 'unsigned long', which may be either 32 or 64 bits.
> + */
> +/* This is the number of 64 bit words sent over the wire */
> +#define BITS_TO_U64S(nr) DIV_ROUND_UP(nr, 64)
> +static int get_bitmap(QEMUFile *f, void *pv, size_t size)
> +{
> +    unsigned long *bmp = pv;
> +    int i, idx = 0;
> +    for (i = 0; i < BITS_TO_U64S(size); i++) {
> +        uint64_t w = qemu_get_be64(f);
> +        bmp[idx++] = w;
> +        if (sizeof(unsigned long) == 4 && idx < BITS_TO_LONGS(size)) {
> +            bmp[idx++] = w >> 32;
> +        }
> +    }
> +    return 0;
> +}
> +
> +static void put_bitmap(QEMUFile *f, void *pv, size_t size)
> +{
> +    unsigned long *bmp = pv;
> +    int i, idx = 0;
> +    for (i = 0; i < BITS_TO_U64S(size); i++) {
> +        uint64_t w = bmp[idx++];
> +        if (sizeof(unsigned long) == 4 && idx < BITS_TO_LONGS(size)) {
> +            w |= ((uint64_t)bmp[idx++]) << 32;
> +        }
> +        qemu_put_be64(f, w);
> +    }
> +}
> +
> +const VMStateInfo vmstate_info_bitmap = {
> +    .name = "bitmap",
> +    .get = get_bitmap,
> +    .put = put_bitmap,
> +};
> +
>   typedef struct CompatEntry {
>       char idstr[256];
>       int instance_id;
> diff --git a/vmstate.h b/vmstate.h
> index 5bd2b76..c45f46e 100644
> --- a/vmstate.h
> +++ b/vmstate.h
> @@ -139,6 +139,7 @@ extern const VMStateInfo vmstate_info_uint64;
>   extern const VMStateInfo vmstate_info_timer;
>   extern const VMStateInfo vmstate_info_buffer;
>   extern const VMStateInfo vmstate_info_unused_buffer;
> +extern const VMStateInfo vmstate_info_bitmap;
>   
>   #define type_check_array(t1,t2,n) ((t1(*)[n])0 - (t2*)0)
>   #define type_check_pointer(t1,t2) ((t1**)0 - (t2*)0)
> @@ -411,6 +412,18 @@ extern const VMStateInfo vmstate_info_unused_buffer;
>       .flags        = VMS_BUFFER,                                      \
>   }
>   
> +/* _field_size should be a uint32_t field in the _state struct giving the

"..should be an int32_t.."

> + * size of the bitmap _field in bits.
> + */
> +#define VMSTATE_BITMAP(_field, _state, _version, _field_size) {      \
> +    .name         = (stringify(_field)),                             \
> +    .version_id   = (_version),                                      \
> +    .size_offset  = vmstate_offset_value(_state, _field_size, int32_t),\
> +    .info         = &vmstate_info_bitmap,                            \
> +    .flags        = VMS_VBUFFER|VMS_POINTER,                         \
> +    .offset       = offsetof(_state, _field),                        \
> +}
> +
>   /* _f : field name
>      _f_n : num of elements field_name
>      _n : num of elements

I've successfully tested this patch with migration from 32bit to 64bit 
little endian host and vice versa. Haven’t tested with 
bigendian-littleendian migration since I don't have a bigendian machine 
at my disposal.

Tested-by: Igor Mitsyanko <i.mitsyanko@samsung.com>