linux-kernel - [PATCH v4 2/4] x86/boot: Add max_addr field in struct boot

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Message-Id: <20191102010911.21460-3-msys.mizuma@gmail.com>
Date:   Fri,  1 Nov 2019 21:09:09 -0400
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Baoquan He <bhe@...hat.com>
Cc:     Masayoshi Mizuma <msys.mizuma@...il.com>,
        Masayoshi Mizuma <m.mizuma@...fujitsu.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/4] x86/boot: Add max_addr field in struct boot_params

From: Masayoshi Mizuma <m.mizuma@...fujitsu.com>

Add max_addr field in struct boot_params. max_addr shows the
maximum memory address to be reachable by memory hot-add.
max_addr is set by parsing ACPI SRAT.

Reviewed-by: Baoquan He <bhe@...hat.com>
Signed-off-by: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
---
 Documentation/x86/zero-page.rst       | 4 ++++
 arch/x86/include/uapi/asm/bootparam.h | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/zero-page.rst b/Documentation/x86/zero-page.rst
index f088f5881..cc3938d68 100644
--- a/Documentation/x86/zero-page.rst
+++ b/Documentation/x86/zero-page.rst
@@ -19,6 +19,7 @@ Offset/Size	Proto	Name			Meaning
 058/008		ALL	tboot_addr      	Physical address of tboot shared page
 060/010		ALL	ist_info		Intel SpeedStep (IST) BIOS support information
 						(struct ist_info)
+078/010		ALL	max_addr		The possible maximum physical memory address [1]_
 080/010		ALL	hd0_info		hd0 disk parameter, OBSOLETE!!
 090/010		ALL	hd1_info		hd1 disk parameter, OBSOLETE!!
 0A0/010		ALL	sys_desc_table		System description table (struct sys_desc_table),
@@ -43,3 +44,6 @@ Offset/Size	Proto	Name			Meaning
 						(array of struct e820_entry)
 D00/1EC		ALL	eddbuf			EDD data (array of struct edd_info)
 ===========	=====	=======================	=================================================
+
+.. [1] max_addr shows the maximum memory address to be reachable by memory
+       hot-add. max_addr is set by parsing ACPI SRAT.
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index db1e24e56..855d30f64 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -165,7 +165,7 @@ struct boot_params {
 	__u64  tboot_addr;				/* 0x058 */
 	struct ist_info ist_info;			/* 0x060 */
 	__u64 acpi_rsdp_addr;				/* 0x070 */
-	__u8  _pad3[8];					/* 0x078 */
+	__u64 max_addr;					/* 0x078 */
 	__u8  hd0_info[16];	/* obsolete! */		/* 0x080 */
 	__u8  hd1_info[16];	/* obsolete! */		/* 0x090 */
 	struct sys_desc_table sys_desc_table; /* obsolete! */	/* 0x0a0 */
-- 
2.20.1