memory: add address_space_translate

Using phys_page_find to translate an AddressSpace to a MemoryRegionSection
is unwieldy.  It requires to pass the page index rather than the address,
and later memory_region_section_addr has to be called.  Replace
memory_region_section_addr with a function that does all of it: call
phys_page_find, compute the offset within the region, and check how
big the current mapping is.  This way, a large flat region can be written
with a single lookup rather than a page at a time.

address_space_translate will also provide a single point where IOMMU
forwarding is implemented.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 17 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index fdf55feea1..688d3f0e96 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -752,23 +752,6 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
                                        hwaddr addr, uint64_t size);
 
 /**
- * memory_region_section_addr: get offset within MemoryRegionSection
- *
- * Returns offset within MemoryRegionSection
- *
- * @section: the memory region section being queried
- * @addr: address in address space
- */
-static inline hwaddr
-memory_region_section_addr(MemoryRegionSection *section,
-                           hwaddr addr)
-{
-    addr -= section->offset_within_address_space;
-    addr += section->offset_within_region;
-    return addr;
-}
-
-/**
  * address_space_sync_dirty_bitmap: synchronize the dirty log for all memory
  *
  * Synchronizes the dirty page log for an entire address space.
@@ -869,6 +852,20 @@ void address_space_write(AddressSpace *as, hwaddr addr,
  */
 void address_space_read(AddressSpace *as, hwaddr addr, uint8_t *buf, int len);
 
+/* address_space_translate: translate an address range into an address space
+ * into a MemoryRegionSection and an address range into that section
+ *
+ * @as: #AddressSpace to be accessed
+ * @addr: address within that address space
+ * @xlat: pointer to address within the returned memory region section's
+ * #MemoryRegion.
+ * @len: pointer to length
+ * @is_write: indicates the transfer direction
+ */
+MemoryRegionSection *address_space_translate(AddressSpace *as, hwaddr addr,
+                                             hwaddr *xlat, hwaddr *len,
+                                             bool is_write);
+
 /* address_space_map: map a physical memory region into a host virtual address
  *
  * May map a subset of the requested range, given by and returned in @plen.