[PATCH v6 2/3] x86/boot: Introduce the kernel_info.setup_type_max

[Daniel Kiper]

This field contains maximal allowed type for setup_data.

Do not bump setup_header version in arch/x86/boot/header.S because it
will be followed by additional changes coming into the Linux/x86 boot
protocol.

Suggested-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
Reviewed-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
---
v6 - suggestions/fixes:
   - fix setup_type_max offset in Documentation/x86/boot.rst
     (suggested by Borislav Petkov),
   - drop "This patch" from the commit message
     (suggested by Borislav Petkov).

v5 - suggestions/fixes:
   - move incorrect references to the setup_indirect to the
     patch introducing it,
   - do not bump setup_header version in arch/x86/boot/header.S
     (suggested by H. Peter Anvin).
---
 Documentation/x86/boot.rst             | 9 ++++++++-
 arch/x86/boot/compressed/kernel_info.S | 5 +++++
 arch/x86/include/uapi/asm/bootparam.h  | 3 +++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/boot.rst b/Documentation/x86/boot.rst
index c60fafda9427..6cdd767c3835 100644
--- a/Documentation/x86/boot.rst
+++ b/Documentation/x86/boot.rst
@@ -73,7 +73,7 @@ Protocol 2.14:	BURNT BY INCORRECT COMMIT ae7e1238e68f2a472a125673ab506d49158c188
 		(x86/boot: Add ACPI RSDP address to setup_header)
 		DO NOT USE!!! ASSUME SAME AS 2.13.
 
-Protocol 2.15:	(Kernel 5.5) Added the kernel_info.
+Protocol 2.15:	(Kernel 5.5) Added the kernel_info and kernel_info.setup_type_max.
 =============	============================================================
 
 .. note::
@@ -981,6 +981,13 @@ Offset/size:	0x0008/4
   This field contains the size of the kernel_info including kernel_info.header
   and kernel_info.kernel_info_var_len_data.
 
+============	==============
+Field name:	setup_type_max
+Offset/size:	0x000c/4
+============	==============
+
+  This field contains maximal allowed type for setup_data.
+
 
 The Image Checksum
 ==================
diff --git a/arch/x86/boot/compressed/kernel_info.S b/arch/x86/boot/compressed/kernel_info.S
index 8ea6f6e3feef..018dacbd753e 100644
--- a/arch/x86/boot/compressed/kernel_info.S
+++ b/arch/x86/boot/compressed/kernel_info.S
@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 
+#include <asm/bootparam.h>
+
 	.section ".rodata.kernel_info", "a"
 
 	.global kernel_info
@@ -12,6 +14,9 @@ kernel_info:
 	/* Size total. */
 	.long	kernel_info_end - kernel_info
 
+	/* Maximal allowed type for setup_data. */
+	.long	SETUP_TYPE_MAX
+
 kernel_info_var_len_data:
 	/* Empty for time being... */
 kernel_info_end:
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index a1ebcd7a991c..dbb41128e5a0 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -11,6 +11,9 @@
 #define SETUP_APPLE_PROPERTIES		5
 #define SETUP_JAILHOUSE			6
 
+/* max(SETUP_*) */
+#define SETUP_TYPE_MAX			SETUP_JAILHOUSE
+
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK	0x07FF
 #define RAMDISK_PROMPT_FLAG		0x8000
-- 
2.11.0