Re: [SeaBIOS] [PATCH v7 4/5] QEMU fw_cfg: Add functions for accessing files by key

[Laszlo Ersek]

On 02/21/17 04:56, [e-mail] wrote:
> From: Ben Warren <[e-mail]>
>
> Due to memory contraints, when resuming from S3 the fw_cfg "files" API
> isn't available.  This adds a simple API to get a file 'key', and to
> write to the file using the key as a reference.
>
> Signed-off-by: Ben Warren <[e-mail]>
> Reviewed-by: Igor Mammedov <[e-mail]>
> Reviewed-by: Laszlo Ersek <[e-mail]>
> ---
>  src/fw/paravirt.c | 41 ++++++++++++++++++++++++++++++-----------
>  src/fw/paravirt.h |  2 ++
>  2 files changed, 32 insertions(+), 11 deletions(-)

Yep, looks good, my R-b stands.

Thanks,
Laszlo
> diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c
> index 4618647..707502d 100644
> --- a/src/fw/paravirt.c
> +++ b/src/fw/paravirt.c
> @@ -329,6 +329,22 @@ qemu_cfg_read_file(struct romfile_s *file, void *dst, u32 maxlen)
>      return file->size;
>  }
>
> +// Bare-bones function for writing a file knowing only its unique
> +// identifying key (select)
> +int
> +qemu_cfg_write_file_simple(void *src, u16 key, u32 offset, u32 len)
> +{
> +    if (offset == 0) {
> +        /* Do it in one transfer */
> +        qemu_cfg_write_entry(src, key, len);
> +    } else {
> +        qemu_cfg_select(key);
> +        qemu_cfg_skip(offset);
> +        qemu_cfg_write(src, len);
> +    }
> +    return len;
> +}
> +
>  int
>  qemu_cfg_write_file(void *src, struct romfile_s *file, u32 offset, u32 len)
>  {
> @@ -339,17 +355,8 @@ qemu_cfg_write_file(void *src, struct romfile_s *file, u32 offset, u32 len)
>          warn_internalerror();
>          return -1;
>      }
> -    struct qemu_romfile_s *qfile;
> -    qfile = container_of(file, struct qemu_romfile_s, file);
> -    if (offset == 0) {
> -        /* Do it in one transfer */
> -        qemu_cfg_write_entry(src, qfile->select, len);
> -    } else {
> -        qemu_cfg_select(qfile->select);
> -        qemu_cfg_skip(offset);
> -        qemu_cfg_write(src, len);
> -    }
> -    return len;
> +    return qemu_cfg_write_file_simple(src, qemu_get_romfile_key(file),
> +                                      offset, len);
>  }
>
> static void
> @@ -370,6 +377,18 @@ qemu_romfile_add(char *name, int select, int skip, int size)
>  }
>
> u16
> +qemu_get_romfile_key(struct romfile_s *file)
> +{
> +    struct qemu_romfile_s *qfile;
> +    if (file->copy != qemu_cfg_read_file) {
> +        warn_internalerror();
> +        return 0;
> +    }
> +    qfile = container_of(file, struct qemu_romfile_s, file);
> +    return qfile->select;
> +}
> +
> +u16
>  qemu_get_present_cpus_count(void)
>  {
>      u16 smp_count = 0;
> diff --git a/src/fw/paravirt.h b/src/fw/paravirt.h
> index fb220d8..16f3d9a 100644
> --- a/src/fw/paravirt.h
> +++ b/src/fw/paravirt.h
> @@ -56,5 +56,7 @@ void qemu_cfg_init(void);
>
> u16 qemu_get_present_cpus_count(void);
>  int qemu_cfg_write_file(void *src, struct romfile_s *file, u32 offset, u32 len);
> +int qemu_cfg_write_file_simple(void *src, u16 key, u32 offset, u32 len);
> +u16 qemu_get_romfile_key(struct romfile_s *file);
>
> #endif