memory: Export a helper to get intersection of a MemoryRegionSection with a given range

Rename the helper to memory_region_section_intersect_range() to make it
more generic. Meanwhile, define the @end as Int128 and replace the
related operations with Int128_* format since the helper is exported as
a wider API.

Suggested-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Link: https://lore.kernel.org/r/20250612082747.51539-2-chenyi.qiang@intel.com
Signed-off-by: Peter Xu <peterx@redhat.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/system/memory.h b/include/system/memory.h
index 0848690ea4..da97753e28 100644
--- a/include/system/memory.h
+++ b/include/system/memory.h
@@ -1212,6 +1212,36 @@ MemoryRegionSection *memory_region_section_new_copy(MemoryRegionSection *s);
 void memory_region_section_free_copy(MemoryRegionSection *s);
 
 /**
+ * memory_region_section_intersect_range: Adjust the memory section to cover
+ * the intersection with the given range.
+ *
+ * @s: the #MemoryRegionSection to be adjusted
+ * @offset: the offset of the given range in the memory region
+ * @size: the size of the given range
+ *
+ * Returns false if the intersection is empty, otherwise returns true.
+ */
+static inline bool memory_region_section_intersect_range(MemoryRegionSection *s,
+                                                         uint64_t offset,
+                                                         uint64_t size)
+{
+    uint64_t start = MAX(s->offset_within_region, offset);
+    Int128 end = int128_min(int128_add(int128_make64(s->offset_within_region),
+                                       s->size),
+                            int128_add(int128_make64(offset),
+                                       int128_make64(size)));
+
+    if (int128_le(end, int128_make64(start))) {
+        return false;
+    }
+
+    s->offset_within_address_space += start - s->offset_within_region;
+    s->offset_within_region = start;
+    s->size = int128_sub(end, int128_make64(start));
+    return true;
+}
+
+/**
  * memory_region_init: Initialize a memory region
  *
  * The region typically acts as a container for other memory regions.  Use