memory: add address_space_access_valid

The old-style IOMMU lets you check whether an access is valid in a
given DMAContext.  There is no equivalent for AddressSpace in the
memory API, implement it with a lookup of the dispatch tree.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 17 insertions, 1 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 688d3f0e96..81e0e416a4 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -866,6 +866,21 @@ MemoryRegionSection *address_space_translate(AddressSpace *as, hwaddr addr,
                                              hwaddr *xlat, hwaddr *len,
                                              bool is_write);
 
+/* address_space_access_valid: check for validity of accessing an address
+ * space range
+ *
+ * Check whether memory is assigned to the given address space range.
+ *
+ * For now, addr and len should be aligned to a page size.  This limitation
+ * will be lifted in the future.
+ *
+ * @as: #AddressSpace to be accessed
+ * @addr: address within that address space
+ * @len: length of the area to be checked
+ * @is_write: indicates the transfer direction
+ */
+bool address_space_access_valid(AddressSpace *as, hwaddr addr, int 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.
diff --git a/include/sysemu/dma.h b/include/sysemu/dma.h
index a52c93a553..02e0dcdfeb 100644
--- a/include/sysemu/dma.h
+++ b/include/sysemu/dma.h
@@ -113,7 +113,8 @@ static inline bool dma_memory_valid(DMAContext *dma,
                                     DMADirection dir)
 {
     if (!dma_has_iommu(dma)) {
-        return true;
+        return address_space_access_valid(dma->as, addr, len,
+                                          dir == DMA_DIRECTION_FROM_DEVICE);
     } else {
         return iommu_dma_memory_valid(dma, addr, len, dir);
     }