[PATCH v5 4/5] LoongArch: enable kexec handover (KHO)

[George Guo <dongtai.guo@linux.dev>]

From: George Guo <guodongtai@kylinos.cn>

Enable ARCH_SUPPORTS_KEXEC_HANDOVER for 64-bit LoongArch.  It selects
EFI_KHO whenever KEXEC_HANDOVER is enabled, so LoongArch uses the
architecture-agnostic EFI configuration table channel
(LINUX_EFI_KEXEC_HANDOVER_GUID) introduced by this series to carry the
KHO state across kexec.

LoongArch boots through EFI without a device tree, so it cannot use the
/chosen FDT path that arm64 and riscv use; the EFI configuration table
channel is its handover transport.  No arch-specific setup.c reader or
machine_kexec_file.c writer is needed -- both live in the generic EFI
code.

Co-developed-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: Kexin Liu <liukexin@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
---
 arch/loongarch/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index a21f51e5815e..5eaa65578d58 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -685,6 +685,10 @@ config ARCH_SUPPORTS_KEXEC
 config ARCH_SUPPORTS_KEXEC_FILE
 	def_bool 64BIT
 
+config ARCH_SUPPORTS_KEXEC_HANDOVER
+	def_bool 64BIT && EFI_STUB
+	select EFI_KHO if KEXEC_HANDOVER
+
 config ARCH_SELECTS_KEXEC_FILE
 	def_bool 64BIT
 	depends on KEXEC_FILE
-- 
2.53.0