xen/memory: Introduce CONFIG_ARCH_ACQUIRE_RESOURCE

New architectures shouldn't be forced to implement no-op stubs for unused
functionality.

Introduce CONFIG_ARCH_ACQUIRE_RESOURCE which can be opted in to, and provide
compatibility logic in xen/mm.h

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/x86/Kconfig

@@ -6,6 +6,7 @@ config X86
 	select ACPI
 	select ACPI_LEGACY_TABLES_LOOKUP
 	select ARCH_SUPPORTS_INT128
+	select ARCH_ACQUIRE_RESOURCE
 	select COMPAT
 	select CORE_PARKING
 	select HAS_ALTERNATIVE

xen/common/Kconfig

@@ -22,6 +22,9 @@ config GRANT_TABLE
 
 	  If unsure, say Y.
 
+config ARCH_ACQUIRE_RESOURCE
+	bool
+
 config HAS_ALTERNATIVE
 	bool
 

xen/include/asm-arm/mm.h

@@ -358,14 +358,6 @@ static inline void put_page_and_type(struct page_info *page)
 
 void clear_and_clean_page(struct page_info *page);
 
-static inline
-int arch_acquire_resource(struct domain *d, unsigned int type, unsigned int id,
-                          unsigned long frame, unsigned int nr_frames,
-                          xen_pfn_t mfn_list[])
-{
-    return -EOPNOTSUPP;
-}
-
 unsigned int arch_get_dma_bitsize(void);
 
 #endif /*  __ARCH_ARM_MM__ */

xen/include/xen/mm.h

@@ -702,4 +702,13 @@ static inline void put_page_alloc_ref(struct page_info *page)
     }
 }
 
+#ifndef CONFIG_ARCH_ACQUIRE_RESOURCE
+static inline int arch_acquire_resource(
+    struct domain *d, unsigned int type, unsigned int id, unsigned long frame,
+    unsigned int nr_frames, xen_pfn_t mfn_list[])
+{
+    return -EOPNOTSUPP;
+}
+#endif /* !CONFIG_ARCH_ACQUIRE_RESOURCE */
+
 #endif /* __XEN_MM_H__ */