exec: Explicitly export target AS from address_space_translate_internal

This adds an AS** parameter to address_space_do_translate()
to make it easier for the next patch to share FlatViews.

This should cause no behavioural change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20170921085110.25598-2-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

exec.c

@@ -476,7 +476,8 @@ static MemoryRegionSection address_space_do_translate(AddressSpace *as,
                                                       hwaddr *xlat,
                                                       hwaddr *plen,
                                                       bool is_write,
-                                                      bool is_mmio)
+                                                      bool is_mmio,
+                                                      AddressSpace **target_as)
 {
     IOMMUTLBEntry iotlb;
     MemoryRegionSection *section;
@@ -503,6 +504,7 @@ static MemoryRegionSection address_space_do_translate(AddressSpace *as,
         }
 
         as = iotlb.target_as;
+        *target_as = iotlb.target_as;
     }
 
     *xlat = addr;
@@ -525,7 +527,7 @@ IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
 
     /* This can never be MMIO. */
     section = address_space_do_translate(as, addr, &xlat, &plen,
-                                         is_write, false);
+                                         is_write, false, &as);
 
     /* Illegal translation */
     if (section.mr == &io_mem_unassigned) {
@@ -548,7 +550,7 @@ IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
     plen -= 1;
 
     return (IOMMUTLBEntry) {
-        .target_as = section.address_space,
+        .target_as = as,
         .iova = addr & ~plen,
         .translated_addr = xlat & ~plen,
         .addr_mask = plen,
@@ -569,7 +571,8 @@ MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
     MemoryRegionSection section;
 
     /* This can be MMIO, so setup MMIO bit. */
-    section = address_space_do_translate(as, addr, xlat, plen, is_write, true);
+    section = address_space_do_translate(as, addr, xlat, plen, is_write, true,
+                                         &as);
     mr = section.mr;
 
     if (xen_enabled() && memory_access_is_direct(mr, is_write)) {