Re: [Qemu-devel] [PATCH v5 10/15] memory: Access MemoryRegion with MemOp semantics

[Richard Henderson <richard.henderson@linaro.org>]

On 7/25/19 11:47 PM, tony.nguyen@bt.com wrote:
> To convert interfaces of MemoryRegion access, MEMOP_SIZE and
> SIZE_MEMOP no-op stubs were introduced to change syntax while keeping
> the existing semantics.
> 
> Now with interfaces converted, we fill the stubs and use MemOp
> semantics.
> 
> Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
> ---
>  include/exec/memop.h  | 5 ++---
>  include/exec/memory.h | 4 ++--
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/include/exec/memop.h b/include/exec/memop.h
> index 09c8d20..f2847e8 100644
> --- a/include/exec/memop.h
> +++ b/include/exec/memop.h
> @@ -106,8 +106,7 @@ typedef enum MemOp {
>      MO_SSIZE = MO_SIZE | MO_SIGN,
>  } MemOp;
> 
> -/* No-op while memory_region_dispatch_[read|write] is converted to MemOp */
> -#define MEMOP_SIZE(op)  (op)    /* MemOp to size.  */
> -#define SIZE_MEMOP(ul)  (ul)    /* Size to MemOp.  */
> +#define MEMOP_SIZE(op)  (1 << ((op) & MO_SIZE)) /* MemOp to size.  */
> +#define SIZE_MEMOP(ul)  (ctzl(ul))              /* Size to MemOp.  */

As mentioned, I'd prefer inline functions.

I think it wouldn't go amiss to do

static inline MemOp size_memop(unsigned size)
{
#ifdef CONFIG_DEBUG_TCG
    /* power of 2 up to 8 */
    assert((size & (size - 1)) == 0 && size >= 1 && size <= 8);
#endif
    return ctz32(size);
}


> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 0ea4843..975b86a 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -1732,7 +1732,7 @@ void mtree_info(bool flatview, bool dispatch_tree, bool owner);
>   * @mr: #MemoryRegion to access
>   * @addr: address within that region
>   * @pval: pointer to uint64_t which the data is written to
> - * @op: size of the access in bytes
> + * @op: size, sign, and endianness of the memory operation
>   * @attrs: memory transaction attributes to use for the access
>   */
>  MemTxResult memory_region_dispatch_read(MemoryRegion *mr,
> @@ -1747,7 +1747,7 @@ MemTxResult memory_region_dispatch_read(MemoryRegion *mr,
>   * @mr: #MemoryRegion to access
>   * @addr: address within that region
>   * @data: data to write
> - * @op: size of the access in bytes
> + * @op: size, sign, and endianness of the memory operation
>   * @attrs: memory transaction attributes to use for the access
>   */
>  MemTxResult memory_region_dispatch_write(MemoryRegion *mr,

As I mentioned, now is when the actual interface change to these functions
should occur.


r~