ANDROID: KVM: arm64: Introduce kvm_has_memrelinquish_services

Used to determine whether memrelinquish services have been
initialised.

Bug: 240239989
Change-Id: I81dd23d8122ea54924d52b3fdc1fc4a8cdb28ea5
Signed-off-by: Keir Fraser <keirf@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>

arch/arm64/include/asm/mem_relinquish.h

@@ -9,6 +9,7 @@
 
 struct page;
 
+bool kvm_has_memrelinquish_services(void);
 void page_relinquish(struct page *page);
 
 #endif	/* __ASM_MEM_RELINQUISH_H */

arch/arm64/mm/mem_relinquish.c

@@ -36,6 +36,12 @@ void kvm_init_memrelinquish_services(void)
 	memshare_granule_sz = res.a0;
 }
 
+bool kvm_has_memrelinquish_services(void)
+{
+	return !!memshare_granule_sz;
+}
+EXPORT_SYMBOL_GPL(kvm_has_memrelinquish_services);
+
 void page_relinquish(struct page *page)
 {
 	phys_addr_t phys, end;

include/linux/mem_relinquish.h

@@ -13,6 +13,7 @@
 
 #else	/* !CONFIG_MEMORY_RELINQUISH */
 
+static inline bool kvm_has_memrelinquish_services(void) { return false; }
 static inline void page_relinquish(struct page *page) { }
 
 #endif	/* CONFIG_MEMORY_RELINQUISH */