kexec: add Kexec HandOver (KHO) generation helpers

Add the infrastructure to generate Kexec HandOver metadata.  Kexec
HandOver is a mechanism that allows Linux to preserve state - arbitrary
properties as well as memory locations - across kexec.

It does so using 2 concepts:

  1) KHO FDT - Every KHO kexec carries a KHO specific flattened device tree
     blob that describes preserved memory regions. Device drivers can
     register to KHO to serialize and preserve their states before kexec.

  2) Scratch Regions - CMA regions that we allocate in the first kernel.
     CMA gives us the guarantee that no handover pages land in those
     regions, because handover pages must be at a static physical memory
     location. We use these regions as the place to load future kexec
     images so that they won't collide with any handover data.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Graf <[email protected]>
Co-developed-by: Mike Rapoport (Microsoft) <[email protected]>
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
Co-developed-by: Pratyush Yadav <[email protected]>
Signed-off-by: Pratyush Yadav <[email protected]>
Co-developed-by: Changyuan Lyu <[email protected]>
Signed-off-by: Changyuan Lyu <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anthony Yznaga <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Ashish Kalra <[email protected]>
Cc: Ben Herrenschmidt <[email protected]>
Cc: Borislav Betkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Gowans <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Marc Rutland <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Saravana Kannan <[email protected]>
Cc: Stanislav Kinsburskii <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleinxer <[email protected]>
Cc: Thomas Lendacky <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 62d7f551b295..b35006d9d49d 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -30,6 +30,7 @@
 #include <linux/crash_dump.h>
 #include <linux/execmem.h>
 #include <linux/vmstat.h>
+#include <linux/kexec_handover.h>
 #include <linux/hugetlb.h>
 #include "internal.h"
 #include "slab.h"
@@ -2770,6 +2771,13 @@ void __init mm_core_init(void)
 	report_meminit();
 	kmsan_init_shadow();
 	stack_depot_early_init();
+
+	/*
+	 * KHO memory setup must happen while memblock is still active, but
+	 * as close as possible to buddy initialization
+	 */
+	kho_memory_init();
+
 	memblock_free_all();
 	mem_init();
 	kmem_cache_init();