Re: [PATCH v4 13/17] softmmu: Pass RAM MemoryRegion and is_write xen_map_cache()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 30 Apr 2024, Edgar E. Iglesias wrote:
> From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxx>
> 
> Propagate MR and is_write to xen_map_cache().
> This is in preparation for adding support for grant mappings.
> 
> No functional change.
> 
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  hw/xen/xen-mapcache.c         | 10 ++++++----
>  include/sysemu/xen-mapcache.h | 11 +++++++----
>  system/physmem.c              | 31 +++++++++++++++++++++++--------
>  3 files changed, 36 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/xen/xen-mapcache.c b/hw/xen/xen-mapcache.c
> index 0365311788..09b5f36d9c 100644
> --- a/hw/xen/xen-mapcache.c
> +++ b/hw/xen/xen-mapcache.c
> @@ -264,7 +264,7 @@ static void xen_remap_bucket(MapCache *mc,
>  
>  static uint8_t *xen_map_cache_unlocked(MapCache *mc,
>                                         hwaddr phys_addr, hwaddr size,
> -                                       uint8_t lock, bool dma)
> +                                       uint8_t lock, bool dma, bool is_write)
>  {
>      MapCacheEntry *entry, *pentry = NULL,
>                    *free_entry = NULL, *free_pentry = NULL;
> @@ -387,13 +387,15 @@ tryagain:
>      return mc->last_entry->vaddr_base + address_offset;
>  }
>  
> -uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
> -                       uint8_t lock, bool dma)
> +uint8_t *xen_map_cache(MemoryRegion *mr,
> +                       hwaddr phys_addr, hwaddr size,
> +                       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);
> +    p = xen_map_cache_unlocked(mapcache, phys_addr, size, lock, dma, 
> is_write);
>      mapcache_unlock(mapcache);
>      return p;
>  }
> diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-mapcache.h
> index 10c2e3082a..1ec9e66752 100644
> --- a/include/sysemu/xen-mapcache.h
> +++ b/include/sysemu/xen-mapcache.h
> @@ -18,8 +18,9 @@ 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(hwaddr phys_addr, hwaddr size,
> -                       uint8_t lock, bool dma);
> +uint8_t *xen_map_cache(MemoryRegion *mr, hwaddr phys_addr, hwaddr size,
> +                       uint8_t lock, bool dma,
> +                       bool is_write);
>  ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
>  void xen_invalidate_map_cache_entry(uint8_t *buffer);
>  void xen_invalidate_map_cache(void);
> @@ -33,10 +34,12 @@ static inline void 
> xen_map_cache_init(phys_offset_to_gaddr_t f,
>  {
>  }
>  
> -static inline uint8_t *xen_map_cache(hwaddr phys_addr,
> +static inline uint8_t *xen_map_cache(MemoryRegion *mr,
> +                                     hwaddr phys_addr,
>                                       hwaddr size,
>                                       uint8_t lock,
> -                                     bool dma)
> +                                     bool dma,
> +                                     bool is_write)
>  {
>      abort();
>  }
> diff --git a/system/physmem.c b/system/physmem.c
> index f114b972a5..ad7a8c7d95 100644
> --- a/system/physmem.c
> +++ b/system/physmem.c
> @@ -2190,11 +2190,22 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t 
> length)
>  
>  /*
>   * Return a host pointer to guest's ram.
> + * For Xen, foreign mappings get created if they don't already exist.
> + *
> + * @block: block for the RAM to lookup (optional and may be NULL).
> + * @addr: address within the memory region.
> + * @size: pointer to requested size (optional and may be NULL).
> + *        size may get modified and return a value smaller than
> + *        what was requested.
> + * @lock: wether to lock the mapping in xen-mapcache until invalidated.
> + * @is_write: hint wether to map RW or RO in the xen-mapcache.
> + *            (optional and may always be set to true).
>   *
>   * Called within RCU critical section.
>   */
>  static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
> -                                 hwaddr *size, bool lock)
> +                                 hwaddr *size, bool lock,
> +                                 bool is_write)
>  {
>      hwaddr len = 0;
>  
> @@ -2217,10 +2228,13 @@ static void *qemu_ram_ptr_length(RAMBlock *block, 
> ram_addr_t addr,
>           * In that case just map the requested area.
>           */
>          if (block->offset == 0) {
> -            return xen_map_cache(addr, len, lock, lock);
> +            return xen_map_cache(block->mr, addr, len, lock, lock,
> +                                 is_write);
>          }
>  
> -        block->host = xen_map_cache(block->offset, block->max_length, 1, 
> lock);
> +        block->host = xen_map_cache(block->mr, block->offset,
> +                                    block->max_length, 1,
> +                                    lock, is_write);
>      }
>  
>      return ramblock_ptr(block, addr);
> @@ -2236,7 +2250,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, 
> ram_addr_t addr,
>   */
>  void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr)
>  {
> -    return qemu_ram_ptr_length(ram_block, addr, NULL, false);
> +    return qemu_ram_ptr_length(ram_block, addr, NULL, false, true);
>  }
>  
>  /* Return the offset of a hostpointer within a ramblock */
> @@ -2746,7 +2760,7 @@ static MemTxResult 
> flatview_write_continue_step(MemTxAttrs attrs,
>      } else {
>          /* RAM case */
>          uint8_t *ram_ptr = qemu_ram_ptr_length(mr->ram_block, mr_addr, l,
> -                                               false);
> +                                               false, true);
>  
>          memmove(ram_ptr, buf, *l);
>          invalidate_and_set_dirty(mr, mr_addr, *l);
> @@ -2839,7 +2853,7 @@ static MemTxResult 
> flatview_read_continue_step(MemTxAttrs attrs, uint8_t *buf,
>      } else {
>          /* RAM case */
>          uint8_t *ram_ptr = qemu_ram_ptr_length(mr->ram_block, mr_addr, l,
> -                                               false);
> +                                               false, false);
>  
>          memcpy(buf, ram_ptr, *l);
>  
> @@ -3233,7 +3247,7 @@ void *address_space_map(AddressSpace *as,
>      *plen = flatview_extend_translation(fv, addr, len, mr, xlat,
>                                          l, is_write, attrs);
>      fuzz_dma_read_cb(addr, *plen, mr);
> -    return qemu_ram_ptr_length(mr->ram_block, xlat, plen, true);
> +    return qemu_ram_ptr_length(mr->ram_block, xlat, plen, true, is_write);
>  }
>  
>  /* Unmaps a memory region previously mapped by address_space_map().
> @@ -3329,7 +3343,8 @@ int64_t address_space_cache_init(MemoryRegionCache 
> *cache,
>          l = flatview_extend_translation(cache->fv, addr, len, mr,
>                                          cache->xlat, l, is_write,
>                                          MEMTXATTRS_UNSPECIFIED);
> -        cache->ptr = qemu_ram_ptr_length(mr->ram_block, cache->xlat, &l, 
> true);
> +        cache->ptr = qemu_ram_ptr_length(mr->ram_block, cache->xlat, &l, 
> true,
> +                                         is_write);
>      } else {
>          cache->ptr = NULL;
>      }
> -- 
> 2.40.1
>