4 files changed, 36 insertions, 10 deletions

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 67a03b20a2db..6d3b0b4fed4e 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -327,7 +327,7 @@ int hmm_vma_fault(struct vm_area_struct *vma,
 #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
 
 
-#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
+#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) ||  IS_ENABLED(CONFIG_DEVICE_PUBLIC)
 struct hmm_devmem;
 
 struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma,
@@ -494,7 +494,7 @@ struct hmm_device {
  */
 struct hmm_device *hmm_device_new(void *drvdata);
 void hmm_device_put(struct hmm_device *hmm_device);
-#endif /* IS_ENABLED(CONFIG_DEVICE_PRIVATE) */
+#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
 
 
 /* Below are for HMM internal use only! Not to be used by device driver! */
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 3a4f69137bc2..f5cf32e80041 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -131,6 +131,7 @@ enum {
         IORES_DESC_PERSISTENT_MEMORY            = 4,
         IORES_DESC_PERSISTENT_MEMORY_LEGACY     = 5,
         IORES_DESC_DEVICE_PRIVATE_MEMORY        = 6,
+        IORES_DESC_DEVICE_PUBLIC_MEMORY         = 7,
 };
 
 /* helpers to define resources */
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 8aa6b82679e2..f8ee1c73ad2d 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -57,10 +57,18 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
  *
  * A more complete discussion of unaddressable memory may be found in
  * include/linux/hmm.h and Documentation/vm/hmm.txt.
+ *
+ * MEMORY_DEVICE_PUBLIC:
+ * Device memory that is cache coherent from device and CPU point of view. This
+ * is use on platform that have an advance system bus (like CAPI or CCIX). A
+ * driver can hotplug the device memory using ZONE_DEVICE and with that memory
+ * type. Any page of a process can be migrated to such memory. However no one
+ * should be allow to pin such memory so that it can always be evicted.
  */
 enum memory_type {
         MEMORY_DEVICE_HOST = 0,
         MEMORY_DEVICE_PRIVATE,
+        MEMORY_DEVICE_PUBLIC,
 };
 
 /*
@@ -92,6 +100,8 @@ enum memory_type {
  * The page_free() callback is called once the page refcount reaches 1
  * (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug.
  * This allows the device driver to implement its own memory management.)
+ *
+ * For MEMORY_DEVICE_PUBLIC only the page_free() callback matter.
  */
 typedef int (*dev_page_fault_t)(struct vm_area_struct *vma,
                                 unsigned long addr,
@@ -134,6 +144,12 @@ static inline bool is_device_private_page(const struct page *page)
         return is_zone_device_page(page) &&
                 page->pgmap->type == MEMORY_DEVICE_PRIVATE;
 }
+
+static inline bool is_device_public_page(const struct page *page)
+{
+        return is_zone_device_page(page) &&
+                page->pgmap->type == MEMORY_DEVICE_PUBLIC;
+}
 #else
 static inline void *devm_memremap_pages(struct device *dev,
                 struct resource *res, struct percpu_ref *ref,
@@ -157,6 +173,11 @@ static inline bool is_device_private_page(const struct page *page)
 {
         return false;
 }
+
+static inline bool is_device_public_page(const struct page *page)
+{
+        return false;
+}
 #endif
 
 /**
diff --git a/include/linux/mm.h b/include/linux/mm.h
index eccdab4bb44a..de66a1127db4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -800,15 +800,16 @@ static inline bool is_zone_device_page(const struct page *page)
 }
 #endif
 
-#ifdef CONFIG_DEVICE_PRIVATE
-void put_zone_device_private_page(struct page *page);
+#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) ||  IS_ENABLED(CONFIG_DEVICE_PUBLIC)
+void put_zone_device_private_or_public_page(struct page *page);
 #else
-static inline void put_zone_device_private_page(struct page *page)
+static inline void put_zone_device_private_or_public_page(struct page *page)
 {
 }
-#endif
+#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
 
 static inline bool is_device_private_page(const struct page *page);
+static inline bool is_device_public_page(const struct page *page);
 
 DECLARE_STATIC_KEY_FALSE(device_private_key);
 
@@ -834,8 +835,9 @@ static inline void put_page(struct page *page)
          * include/linux/memremap.h and HMM for details.
          */
         if (static_branch_unlikely(&device_private_key) &&
-            unlikely(is_device_private_page(page))) {
-                put_zone_device_private_page(page);
+            unlikely(is_device_private_page(page) ||
+                     is_device_public_page(page))) {
+                put_zone_device_private_or_public_page(page);
                 return;
         }
 
@@ -1224,8 +1226,10 @@ struct zap_details {
         pgoff_t last_index;                     /* Highest page->index to unmap */
 };
 
-struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
-                pte_t pte);
+struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
+                             pte_t pte, bool with_public_device);
+#define vm_normal_page(vma, addr, pte) _vm_normal_page(vma, addr, pte, false)
+
 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
                                 pmd_t pmd);