powerpc/fadump: avoid holes in boot memory area when fadump is registered

To register fadump, boot memory area - the size of low memory chunk that
is required for a kernel to boot successfully when booted with restricted
memory, is assumed to have no holes. But this memory area is currently
not protected from hot-remove operations. So, fadump could fail to
re-register after a memory hot-remove operation, if memory is removed
from boot memory area. To avoid this, ensure that memory from boot
memory area is not hot-removed when fadump is registered.

Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 08e00448a355..750bff3b4af3 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -113,6 +113,18 @@ int __init early_init_dt_scan_fw_dump(unsigned long node,
 	return 1;
 }
 
+/*
+ * If fadump is registered, check if the memory provided
+ * falls within boot memory area.
+ */
+int is_fadump_boot_memory_area(u64 addr, ulong size)
+{
+	if (!fw_dump.dump_registered)
+		return 0;
+
+	return (addr + size) > RMA_START && addr <= fw_dump.boot_memory_size;
+}
+
 int is_fadump_active(void)
 {
 	return fw_dump.dump_active;