Re: [Qemu-devel] [PATCH v4 02/15] memory: Access MemoryRegion with MemOp

[Philippe Mathieu-Daudé]

On 7/25/19 11:52 AM, address@hidden wrote:
> Replacing size with size+sign+endianness (MemOp) will enable us to
> collapse the two byte swaps, adjust_endianness and handle_bswap, along
> the I/O path.
> 
> While interfaces are converted, callers will have existing unsigned
> size coerced into a MemOp, and the callee will use this MemOp as an
> unsigned size.
> 
> Signed-off-by: Tony Nguyen <address@hidden>
> ---
>  include/exec/memop.h  | 4 ++++
>  include/exec/memory.h | 9 +++++----
>  memory.c              | 7 +++++--
>  3 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/include/exec/memop.h b/include/exec/memop.h
> index ac58066..09c8d20 100644
> --- a/include/exec/memop.h
> +++ b/include/exec/memop.h
> @@ -106,4 +106,8 @@ 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.  */

SIZE_MEMOP() is never used until patch #10 "memory: Access MemoryRegion
with MemOp semantics", it would be clearer to only introduce the
MEMOP_SIZE() no-op here, and directly introduce the correct SIZE_MEMOP()
macro in patch #10.

> +
>  #endif
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index bb0961d..30b1c58 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -19,6 +19,7 @@
>  #include "exec/cpu-common.h"
>  #include "exec/hwaddr.h"
>  #include "exec/memattrs.h"
> +#include "exec/memop.h"
>  #include "exec/ramlist.h"
>  #include "qemu/queue.h"
>  #include "qemu/int128.h"
> @@ -1731,13 +1732,13 @@ 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
> - * @size: size of the access in bytes
> + * @op: encodes size of the access in bytes
>   * @attrs: memory transaction attributes to use for the access
>   */
>  MemTxResult memory_region_dispatch_read(MemoryRegion *mr,
>                                          hwaddr addr,
>                                          uint64_t *pval,
> -                                        unsigned size,
> +                                        MemOp op,
>                                          MemTxAttrs attrs);
>  /**
>   * memory_region_dispatch_write: perform a write directly to the specified
> @@ -1746,13 +1747,13 @@ MemTxResult memory_region_dispatch_read(MemoryRegion 
> *mr,
>   * @mr: #MemoryRegion to access
>   * @addr: address within that region
>   * @data: data to write
> - * @size: size of the access in bytes
> + * @op: encodes size of the access in bytes
>   * @attrs: memory transaction attributes to use for the access
>   */
>  MemTxResult memory_region_dispatch_write(MemoryRegion *mr,
>                                           hwaddr addr,
>                                           uint64_t data,
> -                                         unsigned size,
> +                                         MemOp op,
>                                           MemTxAttrs attrs);
> 
>  /**
> diff --git a/memory.c b/memory.c
> index 5d8c9a9..6982e19 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1439,10 +1439,11 @@ static MemTxResult 
> memory_region_dispatch_read1(MemoryRegion *mr,
>  MemTxResult memory_region_dispatch_read(MemoryRegion *mr,
>                                          hwaddr addr,
>                                          uint64_t *pval,
> -                                        unsigned size,
> +                                        MemOp op,
>                                          MemTxAttrs attrs)
>  {
>      MemTxResult r;
> +    unsigned size = MEMOP_SIZE(op);
> 
>      if (!memory_region_access_valid(mr, addr, size, false, attrs)) {
>          *pval = unassigned_mem_read(mr, addr, size);
> @@ -1483,9 +1484,11 @@ static bool 
> memory_region_dispatch_write_eventfds(MemoryRegion *mr,
>  MemTxResult memory_region_dispatch_write(MemoryRegion *mr,
>                                           hwaddr addr,
>                                           uint64_t data,
> -                                         unsigned size,
> +                                         MemOp op,
>                                           MemTxAttrs attrs)
>  {
> +    unsigned size = MEMOP_SIZE(op);
> +
>      if (!memory_region_access_valid(mr, addr, size, true, attrs)) {
>          unassigned_mem_write(mr, addr, data, size);
>          return MEMTX_DECODE_ERROR;
> --
> 1.8.3.1
> 
> 
>