Re: [Qemu-devel] [PATCH v2 05/14] exec.c: Convert subpage memory ops to _with_attrs

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> Convert the subpage memory ops to _with_attrs; this will allow
> us to pass the attributes through to the underlying access
> functions. (Nothing uses the attributes yet.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> ---
>  exec.c | 33 +++++++++++++++++++++------------
>  1 file changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 34dafd2..bba6f26 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1941,8 +1941,8 @@ static const MemoryRegionOps watch_mem_ops = {
>      .endianness = DEVICE_NATIVE_ENDIAN,
>  };
>  
> -static uint64_t subpage_read(void *opaque, hwaddr addr,
> -                             unsigned len)
> +static MemTxResult subpage_read(void *opaque, hwaddr addr, uint64_t *data,
> +                                unsigned len, MemTxAttrs attrs)
>  {
>      subpage_t *subpage = opaque;
>      uint8_t buf[8];
> @@ -1951,23 +1951,29 @@ static uint64_t subpage_read(void *opaque, hwaddr addr,
>      printf("%s: subpage %p len %u addr " TARGET_FMT_plx "\n", __func__,
>             subpage, len, addr);
>  #endif
> -    address_space_read(subpage->as, addr + subpage->base, buf, len);
> +    if (address_space_read(subpage->as, addr + subpage->base, buf, len)) {
> +        return MEMTX_DECODE_ERROR;
> +    }

Doesn't this mean we loose potential other error bits that are returned
by address_space_read()? Would MEMTX_ERROR ever potentially be returned?

>      switch (len) {
>      case 1:
> -        return ldub_p(buf);
> +        *data = ldub_p(buf);
> +        return MEMTX_OK;
>      case 2:
> -        return lduw_p(buf);
> +        *data = lduw_p(buf);
> +        return MEMTX_OK;
>      case 4:
> -        return ldl_p(buf);
> +        *data = ldl_p(buf);
> +        return MEMTX_OK;
>      case 8:
> -        return ldq_p(buf);
> +        *data = ldq_p(buf);
> +        return MEMTX_OK;
>      default:
>          abort();
>      }
>  }
>  
> -static void subpage_write(void *opaque, hwaddr addr,
> -                          uint64_t value, unsigned len)
> +static MemTxResult subpage_write(void *opaque, hwaddr addr,
> +                                 uint64_t value, unsigned len, MemTxAttrs attrs)
>  {
>      subpage_t *subpage = opaque;
>      uint8_t buf[8];
> @@ -1993,7 +1999,10 @@ static void subpage_write(void *opaque, hwaddr addr,
>      default:
>          abort();
>      }
> -    address_space_write(subpage->as, addr + subpage->base, buf, len);
> +    if (address_space_write(subpage->as, addr + subpage->base, buf, len)) {
> +        return MEMTX_DECODE_ERROR;
> +    }
> +    return MEMTX_OK;

Same comment as above.

>  }
>  
>  static bool subpage_accepts(void *opaque, hwaddr addr,
> @@ -2010,8 +2019,8 @@ static bool subpage_accepts(void *opaque, hwaddr addr,
>  }
>  
>  static const MemoryRegionOps subpage_ops = {
> -    .read = subpage_read,
> -    .write = subpage_write,
> +    .read_with_attrs = subpage_read,
> +    .write_with_attrs = subpage_write,
>      .impl.min_access_size = 1,
>      .impl.max_access_size = 8,
>      .valid.min_access_size = 1,

-- 
Alex Bennée