Re: [Xen-devel] [PATCH 3/4] hvm/dmop: Implement copy_{to, from}_guest_buf_offset() helpers

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: jennifer.herbert@xxxxxxxxxx [mailto:jennifer.herbert@xxxxxxxxxx]
> Sent: 20 April 2017 19:00
> To: Xen-devel <xen-devel@xxxxxxxxxxxxx>
> Cc: Jennifer Herbert <jennifer.herbert@xxxxxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; Paul Durrant <Paul.Durrant@xxxxxxxxxx>;
> Jan Beulich <JBeulich@xxxxxxxx>; Julien Grall <julien.grall@xxxxxxx>
> Subject: [PATCH 3/4] hvm/dmop: Implement copy_{to,
> from}_guest_buf_offset() helpers
> 
> From: Jennifer Herbert <Jennifer.Herbert@xxxxxxxxxx>
> 
> copy_{to,from}_guest_buf() are now implemented using an offset of 0.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Jennifer Herbert <Jennifer.Herbert@xxxxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> --
> CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/arch/x86/hvm/dm.c | 48 +++++++++++++++++++++++++++++++++----
> -----------
>  1 file changed, 33 insertions(+), 15 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
> index 3607ddb..6990725 100644
> --- a/xen/arch/x86/hvm/dm.c
> +++ b/xen/arch/x86/hvm/dm.c
> @@ -32,10 +32,11 @@ struct dmop_args {
>      struct xen_dm_op_buf buf[2];
>  };
> 
> -static bool _raw_copy_from_guest_buf(void *dst,
> -                                     const struct dmop_args *args,
> -                                     unsigned int buf_idx,
> -                                     size_t dst_bytes)
> +static bool _raw_copy_from_guest_buf_offset(void *dst,
> +                                            const struct dmop_args *args,
> +                                            unsigned int buf_idx,
> +                                            size_t offset_bytes,
> +                                            size_t dst_bytes)
>  {
>      size_t buf_bytes;
> 
> @@ -44,15 +45,20 @@ static bool _raw_copy_from_guest_buf(void *dst,
> 
>      buf_bytes =  args->buf[buf_idx].size;
> 
> -    if ( dst_bytes > buf_bytes )
> +    if ( offset_bytes >= buf_bytes ||
> +         (offset_bytes + dst_bytes) < offset_bytes ||
> +         (offset_bytes + dst_bytes) > buf_bytes )
>          return false;
> 
> -    return !copy_from_guest(dst, args->buf[buf_idx].h, buf_bytes);
> +    return !copy_from_guest_offset(dst, args->buf[buf_idx].h,
> +                                   offset_bytes, dst_bytes);
>  }
> 
> -static bool _raw_copy_to_guest_buf(struct dmop_args *args,
> -                                   unsigned int buf_idx,
> -                                   const void *src, size_t src_bytes)
> +static bool _raw_copy_to_guest_buf_offset(struct dmop_args *args,
> +                                          unsigned int buf_idx,
> +                                          size_t offset_bytes,
> +                                          const void *src,
> +                                          size_t src_bytes)
>  {
>      size_t buf_bytes;
> 
> @@ -61,17 +67,29 @@ static bool _raw_copy_to_guest_buf(struct
> dmop_args *args,
> 
>      buf_bytes = args->buf[buf_idx].size;
> 
> -    if ( src_bytes > buf_bytes )
> +
> +    if ( offset_bytes >= buf_bytes ||
> +         (offset_bytes + src_bytes) < offset_bytes ||
> +         (offset_bytes + src_bytes) > buf_bytes )
>          return false;
> 
> -    return !copy_to_guest(args->buf[buf_idx].h, src, buf_bytes);
> +    return !copy_to_guest_offset(args->buf[buf_idx].h, offset_bytes,
> +                                 src, src_bytes);
>  }
> 
> -#define copy_from_guest_buf(dst, args, buf_idx) \
> -    _raw_copy_from_guest_buf(dst, args, buf_idx, sizeof(*(dst)))
> +#define copy_from_guest_buf_offset(dst, bufs, buf_idx, offset_bytes) \
> +    _raw_copy_from_guest_buf_offset(dst, bufs, buf_idx, offset_bytes, \
> +                                    sizeof(*(dst)))
> +
> +#define copy_to_guest_buf_offset(bufs, buf_idx, offset_bytes, src) \
> +    _raw_copy_to_guest_buf_offset(bufs, buf_idx, offset_bytes, \
> +                                  src, sizeof(*(src)))
> +
> +#define copy_from_guest_buf(dst, bufs, buf_idx) \
> +    copy_from_guest_buf_offset(dst, bufs, buf_idx, 0)
> 
> -#define copy_to_guest_buf(args, buf_idx, src) \
> -    _raw_copy_to_guest_buf(args, buf_idx, src, sizeof(*(src)))
> +#define copy_to_guest_buf(bufs, buf_idx, src) \
> +    copy_to_guest_buf_offset(bufs, buf_idx, 0, src)
> 
>  static int track_dirty_vram(struct domain *d, xen_pfn_t first_pfn,
>                              unsigned int nr, struct xen_dm_op_buf *buf)
> --
> 2.1.4


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