From 893ef61ca2b1e857b950654c1bb57f3624df5dc5 Mon Sep 17 00:00:00 2001
From: snoweay <snoweay@163.com>
Date: Wed, 12 Aug 2020 07:53:13 -0400
Subject: [PATCH] kexec: Add quick kexec support

Add quick kexec option -q and flags.

In normal kexec, relocating kernel may cost 5 ~ 10 seconds, to
copy all segments from vmalloced memory to kernel boot memory,
because of disabled mmu.

We introduce quick kexec to save time of copying memory as above,
just like kdump(kexec on crash), by using reserved memory.

We also add this support in syscall kexec_load of linux kernel
through flags of KEXEC_QUICK.

Add KEXEC_FLAGS_MAX to avoid conflicting with KEXEC_LIVE_UPDATE.
---
 kexec/kexec-syscall.h |  2 ++
 kexec/kexec-xen.h     |  2 +-
 kexec/kexec.c         | 10 ++++++++++
 kexec/kexec.h         |  4 +++-
 4 files changed, 16 insertions(+), 2 deletion(-)

diff --git a/kexec/kexec-syscall.h b/kexec/kexec-syscall.h
index bea29d4..5f22353 100644
--- a/kexec/kexec-syscall.h
+++ b/kexec/kexec-syscall.h
@@ -109,6 +109,8 @@ static inline long kexec_file_load(int kernel_fd, int initrd_fd,
 
 #define KEXEC_ON_CRASH		0x00000001
 #define KEXEC_PRESERVE_CONTEXT	0x00000002
+#define KEXEC_QUICK		0x00000004
+#define KEXEC_FLAGS_MAX	0x00000010
 #define KEXEC_ARCH_MASK		0xffff0000
 
 /* Flags for kexec file based system call */
diff --git a/kexec/kexec-xen.h b/kexec/kexec-xen.h
index 70fb576..d417c90 100644
--- a/kexec/kexec-xen.h
+++ b/kexec/kexec-xen.h
@@ -79,7 +79,7 @@ extern int __xc_interface_close(xc_interface *xch);
 #endif

 #ifndef KEXEC_LIVE_UPDATE
-#define KEXEC_LIVE_UPDATE 0x00000004
+#define KEXEC_LIVE_UPDATE KEXEC_FLAGS_MAX
 #endif

 int xen_get_kexec_range(int range, uint64_t *start, uint64_t *end);
diff --git a/kexec/kexec.c b/kexec/kexec.c
index f63b36b..5b8beca 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -1009,6 +1009,7 @@ void usage(void)
 	       " -l, --load           Load the new kernel into the\n"
 	       "                      current kernel.\n"
 	       " -p, --load-panic     Load the new kernel for use on panic.\n"
+	       " -q, --load-quick     Load the new kernel to quick kexec\n"
 	       " -u, --unload         Unload the current kexec target kernel.\n"
 	       "                      If capture kernel is being unloaded\n"
 	       "                      specify -p with -u.\n"
@@ -1340,6 +1341,7 @@ int main(int argc, char *argv[])
 	int has_opt_load = 0;
 	int do_load = 1;
 	int do_exec = 0;
+	int do_quick = 0;
 	int do_load_jump_back_helper = 0;
 	int do_shutdown = 1;
 	int do_sync = 1, skip_sync = 0;
@@ -1460,6 +1462,14 @@ int main(int argc, char *argv[])
 			kexec_file_flags |= KEXEC_FILE_ON_CRASH;
 			kexec_flags = KEXEC_ON_CRASH;
 			break;
+		case OPT_QUICK:
+			do_load = 1;
+			do_exec = 0;
+			do_shutdown = 0;
+			do_quick = 1;
+			kexec_flags = KEXEC_QUICK;
+			skip_checks = 1;
+			break;
 		case OPT_MEM_MIN:
 			mem_min = strtoul(optarg, &endptr, 0);
 			if (*endptr) {
diff --git a/kexec/kexec.h b/kexec/kexec.h
index 595dd68..9cbc77f 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -218,6 +218,7 @@ extern int file_types;
 #define OPT_UNLOAD		'u'
 #define OPT_TYPE		't'
 #define OPT_PANIC		'p'
+#define OPT_QUICK		'q'
 #define OPT_KEXEC_FILE_SYSCALL	's'
 #define OPT_KEXEC_SYSCALL	'c'
 #define OPT_KEXEC_SYSCALL_AUTO	'a'
@@ -249,6 +250,7 @@ extern int file_types;
 	{ "entry",		1, 0, OPT_ENTRY }, \
 	{ "type",		1, 0, OPT_TYPE }, \
 	{ "load-panic",         0, 0, OPT_PANIC }, \
+	{ "load-quick",         0, 0, OPT_QUICK }, \
 	{ "mem-min",		1, 0, OPT_MEM_MIN }, \
 	{ "mem-max",		1, 0, OPT_MEM_MAX }, \
 	{ "reuseinitrd",	0, 0, OPT_REUSE_INITRD }, \
@@ -259,7 +261,7 @@ extern int file_types;
 	{ "status",		0, 0, OPT_STATUS }, \
 	{ "print-ckr-size",     0, 0, OPT_PRINT_CKR_SIZE }, \
 
-#define KEXEC_OPT_STR "h?vdfixyluet:pscaS"
+#define KEXEC_OPT_STR "h?vdfixyluet:pqscaS"
 
 extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr);
 extern void die(const char *fmt, ...)
-- 
2.30.0