physmem: xen: Conditionalize use of the mapcache

Conditionalize use of the mapcache. This is in preparation
to optionally disable the mapcache at runtime.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

system/physmem.c

@@ -578,7 +578,9 @@ MemoryRegion *flatview_translate(FlatView *fv, hwaddr addr, hwaddr *xlat,
                                     is_write, true, &as, attrs);
     mr = section.mr;
 
-    if (xen_enabled() && memory_access_is_direct(mr, is_write, attrs)) {
+    if (xen_map_cache_enabled() &&
+        memory_access_is_direct(mr, is_write, attrs)) {
+        /* mapcache: Next page may be unmapped or in a different bucket/VA. */
         hwaddr page = ((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - addr;
         *plen = MIN(page, *plen);
     }
@@ -2577,7 +2579,7 @@ static void reclaim_ramblock(RAMBlock *block)
 {
     if (block->flags & RAM_PREALLOC) {
         ;
-    } else if (xen_enabled()) {
+    } else if (xen_map_cache_enabled()) {
         xen_invalidate_map_cache_entry(block->host);
 #if !defined(_WIN32) && !defined(EMSCRIPTEN)
     } else if (block->fd >= 0) {
@@ -2736,7 +2738,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
         len = *size;
     }
 
-    if (xen_enabled() && block->host == NULL) {
+    if (xen_map_cache_enabled() && block->host == NULL) {
         /* We need to check if the requested address is in the RAM
          * because we don't want to map the entire memory in QEMU.
          * In that case just map the requested area.
@@ -2785,7 +2787,7 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
     RAMBlock *block;
     uint8_t *host = ptr;
 
-    if (xen_enabled()) {
+    if (xen_map_cache_enabled()) {
         ram_addr_t ram_addr;
         RCU_READ_LOCK_GUARD();
         ram_addr = xen_ram_addr_from_mapcache(ptr);
@@ -3787,7 +3789,7 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
         if (is_write) {
             invalidate_and_set_dirty(mr, addr1, access_len);
         }
-        if (xen_enabled()) {
+        if (xen_map_cache_enabled()) {
             xen_invalidate_map_cache_entry(buffer);
         }
         memory_region_unref(mr);
@@ -3898,7 +3900,7 @@ void address_space_cache_destroy(MemoryRegionCache *cache)
         return;
     }
 
-    if (xen_enabled()) {
+    if (xen_map_cache_enabled()) {
         xen_invalidate_map_cache_entry(cache->ptr);
     }
     memory_region_unref(cache->mrs.mr);