[PATCH v5 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough

[Masayoshi Mizuma <msys.mizuma@gmail.com>]

From: Masayoshi Mizuma <m.mizuma@jp.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@jp.fujitsu.com>
---
 arch/x86/include/asm/setup.h |  2 ++
 drivers/acpi/numa.c          | 16 ++++++++++++++++
 2 files changed, 18 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..5a11aa5 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)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