Re: [Qemu-devel] [PATCH 1/5] migration/ram.c: Use RAMBlock rather than MemoryRegion

[Paolo Bonzini <pbonzini@redhat.com>]

On 13/08/2015 12:51, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> RAM migration mainly works on RAMBlocks but in a few places
> uses data from MemoryRegions to access the same information that's
> already held in RAMBlocks; clean it up just to avoid the
> MemoryRegion use.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/ram.c | 26 +++++++++++---------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 7f007e6..7df9157 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -497,13 +497,13 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data,
>  
>  /* Called with rcu_read_lock() to protect migration_bitmap */
>  static inline
> -ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
> +ram_addr_t migration_bitmap_find_and_reset_dirty(RAMBlock *rb,
>                                                   ram_addr_t start)
>  {
> -    unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS;
> +    unsigned long base = rb->offset >> TARGET_PAGE_BITS;
>      unsigned long nr = base + (start >> TARGET_PAGE_BITS);
> -    uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr));
> -    unsigned long size = base + (mr_size >> TARGET_PAGE_BITS);
> +    uint64_t rb_size = rb->used_length;
> +    unsigned long size = base + (rb_size >> TARGET_PAGE_BITS);
>      unsigned long *bitmap;
>  
>      unsigned long next;
> @@ -573,7 +573,7 @@ static void migration_bitmap_sync(void)
>      qemu_mutex_lock(&migration_bitmap_mutex);
>      rcu_read_lock();
>      QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
> -        migration_bitmap_sync_range(block->mr->ram_addr, block->used_length);
> +        migration_bitmap_sync_range(block->offset, block->used_length);
>      }
>      rcu_read_unlock();
>      qemu_mutex_unlock(&migration_bitmap_mutex);
> @@ -668,12 +668,11 @@ static int ram_save_page(QEMUFile *f, RAMBlock* block, ram_addr_t offset,
>      int pages = -1;
>      uint64_t bytes_xmit;
>      ram_addr_t current_addr;
> -    MemoryRegion *mr = block->mr;
>      uint8_t *p;
>      int ret;
>      bool send_async = true;
>  
> -    p = memory_region_get_ram_ptr(mr) + offset;
> +    p = block->host + offset;
>  
>      /* In doubt sent page as normal */
>      bytes_xmit = 0;
> @@ -744,7 +743,7 @@ static int do_compress_ram_page(CompressParam *param)
>      RAMBlock *block = param->block;
>      ram_addr_t offset = param->offset;
>  
> -    p = memory_region_get_ram_ptr(block->mr) + (offset & TARGET_PAGE_MASK);
> +    p = block->host + (offset & TARGET_PAGE_MASK);
>  
>      bytes_sent = save_page_header(param->file, block, offset |
>                                    RAM_SAVE_FLAG_COMPRESS_PAGE);
> @@ -852,11 +851,10 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
>  {
>      int pages = -1;
>      uint64_t bytes_xmit;
> -    MemoryRegion *mr = block->mr;
>      uint8_t *p;
>      int ret;
>  
> -    p = memory_region_get_ram_ptr(mr) + offset;
> +    p = block->host + offset;
>  
>      bytes_xmit = 0;
>      ret = ram_control_save_page(f, block->offset,
> @@ -929,14 +927,12 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
>      ram_addr_t offset = last_offset;
>      bool complete_round = false;
>      int pages = 0;
> -    MemoryRegion *mr;
>  
>      if (!block)
>          block = QLIST_FIRST_RCU(&ram_list.blocks);
>  
>      while (true) {
> -        mr = block->mr;
> -        offset = migration_bitmap_find_and_reset_dirty(mr, offset);
> +        offset = migration_bitmap_find_and_reset_dirty(block, offset);
>          if (complete_round && block == last_seen_block &&
>              offset >= last_offset) {
>              break;
> @@ -1344,7 +1340,7 @@ static inline void *host_from_stream_offset(QEMUFile *f,
>              return NULL;
>          }
>  
> -        return memory_region_get_ram_ptr(block->mr) + offset;
> +        return block->host + offset;
>      }
>  
>      len = qemu_get_byte(f);
> @@ -1354,7 +1350,7 @@ static inline void *host_from_stream_offset(QEMUFile *f,
>      QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
>          if (!strncmp(id, block->idstr, sizeof(id)) &&
>              block->max_length > offset) {
> -            return memory_region_get_ram_ptr(block->mr) + offset;
> +            return block->host + offset;
>          }
>      }
>  
> 

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

It would be nice in a follow-up patch to move RAMBlock-related
definitions into include/exec/ram_addr.h.

Paolo