linux-kernel - [PATCH v6 2/3] ACPI/NUMA: Add warning message if the padding size for KASLR is not enough

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Message-Id: <20181003013323.4162-3-msys.mizuma@gmail.com>
Date:   Tue,  2 Oct 2018 21:33:22 -0400
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Baoquan He <bhe@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     Masayoshi Mizuma <msys.mizuma@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 2/3] ACPI/NUMA: Add warning message if the padding size for KASLR is not enough

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>
---
 drivers/acpi/numa.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 8516760..420ed2c 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 +436,7 @@ acpi_table_parse_srat(enum acpi_srat_type id,
 int __init acpi_numa_init(void)
 {
 	int cnt = 0;
+	u64 max_possible_phys, max_actual_phys, threshold;
 
 	if (acpi_disabled)
 		return -EINVAL;
@@ -463,6 +465,20 @@ int __init acpi_numa_init(void)
 
 		cnt = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
 					    acpi_parse_memory_affinity, 0);
+
+		/* check the padding size for KASLR is enough. */
+		if (parsed_numa_memblks && kaslr_enabled()) {
+			max_actual_phys = roundup(PFN_PHYS(max_pfn),
+							1ULL << 40);
+			max_possible_phys = roundup(PFN_PHYS(max_possible_pfn),
+							1ULL << 40);
+			threshold = max_actual_phys +
+				((u64)get_rand_mem_physical_padding() << 40);
+
+			if (max_possible_phys > threshold)
+				pr_warn("Set 'rand_mem_physical_padding=%llu' to avoid memory hotadd failure.\n",
+				  (max_possible_phys - max_actual_phys) >> 40);
+		}
 	}
 
 	/* SLIT: System Locality Information Table */
-- 
2.18.0