From 0db6896ff6332ba694f1e61b93ae3b2640317633 Mon Sep 17 00:00:00 2001
From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Date: Mon, 20 Aug 2018 13:47:32 +0530
Subject: [PATCH] powerpc/fadump: Do not allow hot-remove memory from fadump
 reserved area.

References: bsc#1120937, FATE#321840, FATE#325306
Patch-mainline: v5.0-rc1
Git-commit: 0db6896ff6332ba694f1e61b93ae3b2640317633

For fadump to work successfully there should not be any holes in reserved
memory ranges where kernel has asked firmware to move the content of old
kernel memory in event of crash. Now that fadump uses CMA for reserved
area, this memory area is now not protected from hot-remove operations
unless it is cma allocated. Hence, fadump service can fail to re-register
after the hot-remove operation, if hot-removed memory belongs to fadump
reserved region. To avoid this make sure that memory from fadump reserved
area is not hot-removable if fadump is registered.

However, if user still wants to remove that memory, he can do so by
manually stopping fadump service before hot-remove operation.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/include/asm/fadump.h               |  2 +-
 arch/powerpc/kernel/fadump.c                    | 10 ++++++++--
 arch/powerpc/platforms/pseries/hotplug-memory.c |  7 +++++--
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h
index 0a4e37159276..188776befaf9 100644
--- a/arch/powerpc/include/asm/fadump.h
+++ b/arch/powerpc/include/asm/fadump.h
@@ -205,7 +205,7 @@ struct fad_crash_memory_ranges {
 	unsigned long long	size;
 };
 
-extern int is_fadump_boot_memory_area(u64 addr, ulong size);
+extern int is_fadump_memory_area(u64 addr, ulong size);
 extern int early_init_dt_scan_fw_dump(unsigned long node,
 		const char *uname, int depth, void *data);
 extern int fadump_reserve_mem(void);
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index b7f83d6eb697..45a8d0be1c96 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -183,13 +183,19 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 
 /*
  * If fadump is registered, check if the memory provided
- * falls within boot memory area.
+ * falls within boot memory area and reserved memory area.
  */
-int is_fadump_boot_memory_area(u64 addr, ulong size)
+int is_fadump_memory_area(u64 addr, ulong size)
 {
+	u64 d_start = fw_dump.reserve_dump_area_start;
+	u64 d_end = d_start + fw_dump.reserve_dump_area_size;
+
 	if (!fw_dump.dump_registered)
 		return 0;
 
+	if (((addr + size) > d_start) && (addr <= d_end))
+		return 1;
+
 	return (addr + size) > RMA_START && addr <= fw_dump.boot_memory_size;
 }
 
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 3b881ac66d9a..be8a6db3558e 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -353,8 +353,11 @@ static bool lmb_is_removable(struct drmem_lmb *lmb)
 	phys_addr = lmb->base_addr;
 
 #ifdef CONFIG_FA_DUMP
-	/* Don't hot-remove memory that falls in fadump boot memory area */
-	if (is_fadump_boot_memory_area(phys_addr, block_sz))
+	/*
+	 * Don't hot-remove memory that falls in fadump boot memory area
+	 * and memory that is reserved for capturing old kernel memory.
+	 */
+	if (is_fadump_memory_area(phys_addr, block_sz))
 		return false;
 #endif
 
-- 
2.19.2