Re: [PATCH v5 6/8] xen: mapcache: Pass the ram_addr offset to xen_map_cache()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 3 May 2024, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxx>
> 
> Pass the ram_addr offset to xen_map_cache.
> This is in preparation for adding grant mappings that need
> to compute the address within the RAMBlock.
> 
> No functional changes.
> 
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
> ---
>  hw/xen/xen-mapcache.c         | 16 +++++++++++-----
>  include/sysemu/xen-mapcache.h |  2 ++
>  system/physmem.c              |  9 +++++----
>  3 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
> index ec95445696..26bc38a9e3 100644
> --- a/hw/xen/xen-mapcache.c
> +++ b/hw/xen/xen-mapcache.c
> @@ -167,7 +167,8 @@ static void xen_remap_bucket(MapCache *mc,
>                               void *vaddr,
>                               hwaddr size,
>                               hwaddr address_index,
> -                             bool dummy)
> +                             bool dummy,
> +                             ram_addr_t ram_offset)
>  {
>      uint8_t *vaddr_base;
>      xen_pfn_t *pfns;
> @@ -266,6 +267,7 @@ static void xen_remap_bucket(MapCache *mc,
>  
>  static uint8_t *xen_map_cache_unlocked(MapCache *mc,
>                                         hwaddr phys_addr, hwaddr size,
> +                                       ram_addr_t ram_offset,
>                                         uint8_t lock, bool dma, bool is_write)
>  {
>      MapCacheEntry *entry, *pentry = NULL,
> @@ -337,14 +339,16 @@ tryagain:
>      if (!entry) {
>          entry = g_new0(MapCacheEntry, 1);
>          pentry->next = entry;
> -        xen_remap_bucket(mc, entry, NULL, cache_size, address_index, dummy);
> +        xen_remap_bucket(mc, entry, NULL, cache_size, address_index, dummy,
> +                         ram_offset);
>      } else if (!entry->lock) {
>          if (!entry->vaddr_base || entry->paddr_index != address_index ||
>                  entry->size != cache_size ||
>                  !test_bits(address_offset >> XC_PAGE_SHIFT,
>                      test_bit_size >> XC_PAGE_SHIFT,
>                      entry->valid_mapping)) {
> -            xen_remap_bucket(mc, entry, NULL, cache_size, address_index, 
> dummy);
> +            xen_remap_bucket(mc, entry, NULL, cache_size, address_index, 
> dummy,
> +                             ram_offset);
>          }
>      }
>  
> @@ -391,13 +395,15 @@ tryagain:
>  
>  uint8_t *xen_map_cache(MemoryRegion *mr,
>                         hwaddr phys_addr, hwaddr size,
> +                       ram_addr_t ram_addr_offset,
>                         uint8_t lock, bool dma,
>                         bool is_write)
>  {
>      uint8_t *p;
>  
>      mapcache_lock(mapcache);
> -    p = xen_map_cache_unlocked(mapcache, phys_addr, size, lock, dma, 
> is_write);
> +    p = xen_map_cache_unlocked(mapcache, phys_addr, size, ram_addr_offset,
> +                               lock, dma, is_write);
>      mapcache_unlock(mapcache);
>      return p;
>  }
> @@ -632,7 +638,7 @@ static uint8_t *xen_replace_cache_entry_unlocked(MapCache 
> *mc,
>      trace_xen_replace_cache_entry_dummy(old_phys_addr, new_phys_addr);
>  
>      xen_remap_bucket(mc, entry, entry->vaddr_base,
> -                     cache_size, address_index, false);
> +                     cache_size, address_index, false, new_phys_addr);

Everything else makes sense, but I don't understand how can it be that
new_phys_addr is the block->offset here?


>      if (!test_bits(address_offset >> XC_PAGE_SHIFT,
>                  test_bit_size >> XC_PAGE_SHIFT,
>                  entry->valid_mapping)) {
> diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-mapcache.h
> index 1ec9e66752..b5e3ea1bc0 100644
> --- a/include/sysemu/xen-mapcache.h
> +++ b/include/sysemu/xen-mapcache.h
> @@ -19,6 +19,7 @@ typedef hwaddr (*phys_offset_to_gaddr_t)(hwaddr phys_offset,
>  void xen_map_cache_init(phys_offset_to_gaddr_t f,
>                          void *opaque);
>  uint8_t *xen_map_cache(MemoryRegion *mr, hwaddr phys_addr, hwaddr size,
> +                       ram_addr_t ram_addr_offset,
>                         uint8_t lock, bool dma,
>                         bool is_write);
>  ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
> @@ -37,6 +38,7 @@ static inline void 
> xen_map_cache_init(phys_offset_to_gaddr_t f,
>  static inline uint8_t *xen_map_cache(MemoryRegion *mr,
>                                       hwaddr phys_addr,
>                                       hwaddr size,
> +                                     ram_addr_t ram_addr_offset,
>                                       uint8_t lock,
>                                       bool dma,
>                                       bool is_write)
> diff --git a/system/physmem.c b/system/physmem.c
> index b7847db1a2..33d09f7571 100644
> --- a/system/physmem.c
> +++ b/system/physmem.c
> @@ -2231,13 +2231,14 @@ static void *qemu_ram_ptr_length(RAMBlock *block, 
> ram_addr_t addr,
>           */
>          if (xen_mr_is_memory(block->mr)) {
>              return xen_map_cache(block->mr, block->offset + addr,
> -                                 len, lock, lock,
> -                                 is_write);
> +                                 len, block->offset,
> +                                 lock, lock, is_write);
>          }
>  
>          block->host = xen_map_cache(block->mr, block->offset,
> -                                    block->max_length, 1,
> -                                    lock, is_write);
> +                                    block->max_length,
> +                                    block->offset,
> +                                    1, lock, is_write);
>      }

This is OK but it is really making it clear that there is a mistake in
the code. OK for now but it is something to fix in the future.


>      return ramblock_ptr(block, addr);
> -- 
> 2.40.1
>