s390/kexec: set end-of-ipl flag in last diag308 call

If the facility IPL-complete-control is present then the last diag308
call made by kexec shall set the end-of-ipl flag in the subcode register
to signal the hypervisor that this is the last diag308 call made by Linux.
Only the diag308 calls made during a regular kexec need to set
the end-of-ipl flag, in all other cases the hypervisor will ignore it.

Signed-off-by: Alexander Egorenkov <[e-mail]>
Reviewed-by: Heiko Carstens <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/include/asm/ipl.h

···
  * DIAG 308 support
  */
 enum diag308_subcode  {
+	DIAG308_CLEAR_RESET = 0,
+	DIAG308_LOAD_NORMAL_RESET = 1,
 	DIAG308_REL_HSA = 2,
 	DIAG308_LOAD_CLEAR = 3,
 	DIAG308_LOAD_NORMAL_DUMP = 4,
 	DIAG308_SET = 5,
 	DIAG308_STORE = 6,
 	DIAG308_LOAD_NORMAL = 7,
+};
+
+enum diag308_subcode_flags {
+	DIAG308_FLAG_EI = 1UL << 16,
 };
 
 enum diag308_rc {

arch/s390/kernel/machine_kexec.c

···
 #include <asm/stacktrace.h>
 #include <asm/switch_to.h>
 #include <asm/nmi.h>
+#include <asm/sclp.h>
 
-typedef void (*relocate_kernel_t)(kimage_entry_t *, unsigned long);
+typedef void (*relocate_kernel_t)(kimage_entry_t *, unsigned long,
+				  unsigned long);
 
 extern const unsigned char relocate_kernel[];
 extern const unsigned long long relocate_kernel_len;
···
  */
 static void __do_machine_kexec(void *data)
 {
+	unsigned long diag308_subcode;
 	relocate_kernel_t data_mover;
 	struct kimage *image = data;
 
···
 
 	__arch_local_irq_stnsm(0xfb); /* disable DAT - avoid no-execute */
 	/* Call the moving routine */
-	(*data_mover)(&image->head, image->start);
+	diag308_subcode = DIAG308_CLEAR_RESET;
+	if (sclp.has_iplcc)
+		diag308_subcode |= DIAG308_FLAG_EI;
+	(*data_mover)(&image->head, image->start, diag308_subcode);
 
 	/* Die if kexec returns */
 	disabled_wait();

arch/s390/kernel/relocate_kernel.S

···
  * moves the new kernel to its destination...
  * %r2 = pointer to first kimage_entry_t
  * %r3 = start address - where to jump to after the job is done...
+ * %r4 = subcode
  *
  * %r5 will be used as temp. storage
  * %r6 holds the destination address
···
 		jo	0b
 		j	.base
 	.done:
-		sgr	%r0,%r0		# clear register r0
+		lgr	%r0,%r4		# subcode
 		cghi	%r3,0
 		je	.diag
 		la	%r4,load_psw-.base(%r13)	# load psw-address into the register