linux-kernel - [PATCH v4 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough

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Message-Id: <20180927203146.12201-3-msys.mizuma@gmail.com>
Date:   Thu, 27 Sep 2018 16:31:45 -0400
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "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 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough

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

Add warning message if the padding size for KASLR,
rand_mem_physical_padding, is not enough. The message also
says the suitable padding size.

Signed-off-by: Masayoshi Mizuma <m.mizuma@...fujitsu.com>
---
 arch/x86/include/asm/setup.h |  2 ++
 drivers/acpi/numa.c          | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index ae13bc9..65a5bf8 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -80,6 +80,8 @@ static inline unsigned long kaslr_offset(void)
 	return (unsigned long)&_text - __START_KERNEL;
 }
 
+extern int rand_mem_physical_padding;
+
 /*
  * Do NOT EVER look at the BIOS memory size location.
  * It does not work on many machines.
diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 8516760..9c3cc3c 100644
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -32,6 +32,7 @@
 #include <linux/numa.h>
 #include <linux/nodemask.h>
 #include <linux/topology.h>
+#include <asm/setup.h>
 
 static nodemask_t nodes_found_map = NODE_MASK_NONE;
 
@@ -435,6 +436,8 @@ acpi_table_parse_srat(enum acpi_srat_type id,
 int __init acpi_numa_init(void)
 {
 	int cnt = 0;
+	u32 max_phys_addr_tb;
+	u64 max_phys_addr;
 
 	if (acpi_disabled)
 		return -EINVAL;
@@ -463,6 +466,17 @@ int __init acpi_numa_init(void)
 
 		cnt = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
 					    acpi_parse_memory_affinity, 0);
+
+		if (parsed_numa_memblks && kaslr_enabled()) {
+			max_phys_addr = PFN_PHYS(max_possible_pfn);
+			max_phys_addr_tb = (roundup(max_phys_addr, 1ULL << 40)) >> 40;
+
+			if (max_phys_addr_tb > rand_mem_physical_padding)
+				pr_warn("Set 'rand_mem_physical_padding=%d' "
+					"as the kernel parameter. "
+					"Otherwise, memory hotadd may be failed.\n",
+					max_phys_addr_tb);
+		}
 	}
 
 	/* SLIT: System Locality Information Table */
-- 
2.18.0