[RFC PATCH v4 11/28] x86: Add support to determine the E820 type of an address

[Tom Lendacky <thomas.lendacky@xxxxxxx>]

This patch adds support to return the E820 type associated with an address
range.

Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 arch/x86/include/asm/e820/api.h   |    2 ++
 arch/x86/include/asm/e820/types.h |    2 ++
 arch/x86/kernel/e820.c            |   26 +++++++++++++++++++++++---
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h
index 8e0f8b8..7c1bdc9 100644
--- a/arch/x86/include/asm/e820/api.h
+++ b/arch/x86/include/asm/e820/api.h
@@ -38,6 +38,8 @@
 extern void e820__reallocate_tables(void);
 extern void e820__register_nosave_regions(unsigned long limit_pfn);
 
+extern enum e820_type e820__get_entry_type(u64 start, u64 end);
+
 /*
  * Returns true iff the specified range [start,end) is completely contained inside
  * the ISA region.
diff --git a/arch/x86/include/asm/e820/types.h b/arch/x86/include/asm/e820/types.h
index 4adeed0..bf49591 100644
--- a/arch/x86/include/asm/e820/types.h
+++ b/arch/x86/include/asm/e820/types.h
@@ -7,6 +7,8 @@
  * These are the E820 types known to the kernel:
  */
 enum e820_type {
+	E820_TYPE_INVALID	= 0,
+
 	E820_TYPE_RAM		= 1,
 	E820_TYPE_RESERVED	= 2,
 	E820_TYPE_ACPI		= 3,
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 6e9b26f..2ee7ee2 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -84,7 +84,8 @@ bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
  * Note: this function only works correctly once the E820 table is sorted and
  * not-overlapping (at least for the range specified), which is the case normally.
  */
-bool __init e820__mapped_all(u64 start, u64 end, enum e820_type type)
+static struct e820_entry *__e820__mapped_all(u64 start, u64 end,
+					     enum e820_type type)
 {
 	int i;
 
@@ -110,9 +111,28 @@ bool __init e820__mapped_all(u64 start, u64 end, enum e820_type type)
 		 * coverage of the desired range exists:
 		 */
 		if (start >= end)
-			return 1;
+			return entry;
 	}
-	return 0;
+
+	return NULL;
+}
+
+/*
+ * This function checks if the entire range <start,end> is mapped with type.
+ */
+bool __init e820__mapped_all(u64 start, u64 end, enum e820_type type)
+{
+	return __e820__mapped_all(start, end, type) ? 1 : 0;
+}
+
+/*
+ * This function returns the type associated with the range <start,end>.
+ */
+enum e820_type e820__get_entry_type(u64 start, u64 end)
+{
+	struct e820_entry *entry = __e820__mapped_all(start, end, 0);
+
+	return entry ? entry->type : E820_TYPE_INVALID;
 }
 
 /*