exec: add wrapper for host pointer access

host pointer accesses force pointer math, let's
add a wrapper to make them safer.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

include/exec/cpu-all.h

@@ -313,6 +313,11 @@ typedef struct RAMBlock {
     int fd;
 } RAMBlock;
 
+static inline void *ramblock_ptr(RAMBlock *block, ram_addr_t offset)
+{
+    return (char *)block->host + offset;
+}
+
 typedef struct RAMList {
     QemuMutex mutex;
     /* Protected by the iothread lock.  */