[RFC V2 22/37] kvm, x86: Distinguish dmemfs page from mmio page

[yulei . kernel]

From: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>

Dmem page is pfn invalid but not mmio, introduce API
is_dmem_pfn() to distinguish that.

Signed-off-by: Chen Zhuo <sagazchen@xxxxxxxxxxx>
Signed-off-by: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c | 1 +
 include/linux/dmem.h   | 7 +++++++
 mm/dmem.c              | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5bb1939..394508f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -43,6 +43,7 @@
 #include <linux/hash.h>
 #include <linux/kern_levels.h>
 #include <linux/kthread.h>
+#include <linux/dmem.h>
 
 #include <asm/page.h>
 #include <asm/memtype.h>
diff --git a/include/linux/dmem.h b/include/linux/dmem.h
index 8682d63..59d3ef14 100644
--- a/include/linux/dmem.h
+++ b/include/linux/dmem.h
@@ -19,11 +19,18 @@
 		     unsigned int try_max, unsigned int *result_nr);
 
 void dmem_free_pages(phys_addr_t addr, unsigned int dpages_nr);
+bool is_dmem_pfn(unsigned long pfn);
 #define dmem_free_page(addr)	dmem_free_pages(addr, 1)
 #else
 static inline int dmem_reserve_init(void)
 {
 	return 0;
 }
+
+static inline bool is_dmem_pfn(unsigned long pfn)
+{
+	return 0;
+}
+
 #endif
 #endif	/* _LINUX_DMEM_H */
diff --git a/mm/dmem.c b/mm/dmem.c
index 2e61dbd..eb6df70 100644
--- a/mm/dmem.c
+++ b/mm/dmem.c
@@ -972,3 +972,10 @@ void dmem_free_pages(phys_addr_t addr, unsigned int dpages_nr)
 }
 EXPORT_SYMBOL(dmem_free_pages);
 
+bool is_dmem_pfn(unsigned long pfn)
+{
+	struct dmem_node *dnode;
+
+	return !!find_dmem_region(__pfn_to_phys(pfn), &dnode);
+}
+EXPORT_SYMBOL(is_dmem_pfn);
-- 
1.8.3.1