memregion: Support fine grained invalidate by cpu_cache_invalidate_memregion()

Extend cpu_cache_invalidate_memregion() to support invalidating a
particular range of memory by introducing start and length parameters.
Control of types of invalidation is left for when use cases turn up. For
now everything is Clean and Invalidate.

Where the range is unknown, use the provided cpu_cache_invalidate_all()
helper to act as documentation of intent in a fashion that is clearer than
passing (0, -1) to cpu_cache_invalidate_memregion().

Signed-off-by: Yicong Yang <[e-mail]>
Reviewed-by: Dan Williams <[e-mail]>
Acked-by: Davidlohr Bueso <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>
Signed-off-by: Conor Dooley <[e-mail]>

arch/x86/mm/pat/set_memory.c

···
 }
 EXPORT_SYMBOL_NS_GPL(cpu_cache_has_invalidate_memregion, "DEVMEM");
 
-int cpu_cache_invalidate_memregion(void)
+int cpu_cache_invalidate_memregion(phys_addr_t start, size_t len)
 {
 	if (WARN_ON_ONCE(!cpu_cache_has_invalidate_memregion()))
 		return -ENXIO;

drivers/cxl/core/region.c

···
 		return -ENXIO;
 	}
 
-	cpu_cache_invalidate_memregion();
+	if (!cxlr->params.res)
+		return -ENXIO;
+	cpu_cache_invalidate_memregion(cxlr->params.res->start,
+				       resource_size(cxlr->params.res));
 	return 0;
 }
 

drivers/nvdimm/region.c

···
 	 * here is ok.
 	 */
 	if (cpu_cache_has_invalidate_memregion())
-		cpu_cache_invalidate_memregion();
+		cpu_cache_invalidate_all();
 }
 
 static int child_notify(struct device *dev, void *data)

drivers/nvdimm/region_devs.c

···
 		}
 	}
 
-	cpu_cache_invalidate_memregion();
+	cpu_cache_invalidate_all();
 out:
 	for (i = 0; i < nd_region->ndr_mappings; i++) {
 		struct nd_mapping *nd_mapping = &nd_region->mapping[i];

include/linux/memregion.h

···
 /**
  * cpu_cache_invalidate_memregion - drop any CPU cached data for
  *     memregion
+ * @start: start physical address of the target memory region.
+ * @len: length of the target memory region. -1 for all the regions of
+ *       the target type.
  *
  * Perform cache maintenance after a memory event / operation that
  * changes the contents of physical memory in a cache-incoherent manner.
···
  * the cache maintenance.
  */
 #ifdef CONFIG_ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
-int cpu_cache_invalidate_memregion(void);
+int cpu_cache_invalidate_memregion(phys_addr_t start, size_t len);
 bool cpu_cache_has_invalidate_memregion(void);
 #else
 static inline bool cpu_cache_has_invalidate_memregion(void)
···
 	return false;
 }
 
-static inline int cpu_cache_invalidate_memregion(void)
+static inline int cpu_cache_invalidate_memregion(phys_addr_t start, size_t len)
 {
 	WARN_ON_ONCE("CPU cache invalidation required");
 	return -ENXIO;
 }
 #endif
+
+static inline int cpu_cache_invalidate_all(void)
+{
+	return cpu_cache_invalidate_memregion(0, -1);
+}
+
 #endif /* _MEMREGION_H_ */