kexec: add config option for KHO

We have all generic code in place now to support Kexec with KHO.  This
patch adds a config option that depends on architecture support to enable
KHO support.

Link: https://lkml.kernel.org/r/20250509074635.3187114-9-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
index 4d111f871951676544ed248b394c22b157b9536a..4fa212909d69974b02c7d1d9462eaf8666d44b5f 100644 (file)
--- a/kernel/Kconfig.kexec
+++ b/kernel/Kconfig.kexec
@@ -95,6 +95,20 @@ config KEXEC_JUMP
          Jump between original kernel and kexeced kernel and invoke
          code in physical address mode via KEXEC
 
+config KEXEC_HANDOVER
+       bool "kexec handover"
+       depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
+       select MEMBLOCK_KHO_SCRATCH
+       select KEXEC_FILE
+       select DEBUG_FS
+       select LIBFDT
+       select CMA
+       help
+         Allow kexec to hand over state across kernels by generating and
+         passing additional metadata to the target kernel. This is useful
+         to keep data or state alive across the kexec. For this to work,
+         both source and target kernels need to have this option enabled.
+
 config CRASH_DUMP
        bool "kernel crash dumps"
        default ARCH_DEFAULT_CRASH_DUMP