On 2/20/2017 2:09 PM, Borislav Petkov wrote:

On Thu, Feb 16, 2017 at 09:44:30AM -0600, Tom Lendacky wrote:

quoted

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

s/This patch adds/Add/

quoted

range.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 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,
+

Now this is strange - ACPI spec doesn't explicitly say that range type 0
is invalid. Am I looking at the wrong place?

"Table 15-312 Address Range Types12" in ACPI spec 6.

If 0 is really the invalid entry, then e820_print_type() needs updating
too. And then the invalid-entry-add should be a separate patch.

The 0 return (originally) was to indicate that an e820 entry for the
range wasn't found. This series just gave it a name.  So it's not that
the type field held a 0.  Since 0 isn't defined in the ACPI spec I don't
see an issue with creating it and I can add a comment to the effect that
this value is used for the type when an e820 entry isn't found. I could
always rename it to E820_TYPE_NOT_FOUND if that would help.

Or if we want to guard against ACPI adding a type 0 in the future, I
could make the function return an int and then return -EINVAL if an e820
entry isn't found.  This might be the better option.

Thanks,
Tom

quoted

 	E820_TYPE_RAM		= 1,
 	E820_TYPE_RESERVED	= 2,
 	E820_TYPE_ACPI		= 3,

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