[S390] Use diagnose 308 for system reset

The diagnose 308 call is the prefered method for clearing all ongoing I/O.
Therefore if it is available we use it instead of doing a manual reset.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

3 files changed, 43 insertions, 0 deletions

diff --git a/arch/s390/include/asm/ipl.h b/arch/s390/include/asm/ipl.h
index 5e95d95450b3..97cc4403fabf 100644
--- a/arch/s390/include/asm/ipl.h
+++ b/arch/s390/include/asm/ipl.h
@@ -167,5 +167,6 @@ enum diag308_rc {
 };
 
 extern int diag308(unsigned long subcode, void *addr);
+extern void diag308_reset(void);
 
 #endif /* _ASM_S390_IPL_H */
diff --git a/arch/s390/kernel/base.S b/arch/s390/kernel/base.S
index 209938c1dfc8..255435663bf8 100644
--- a/arch/s390/kernel/base.S
+++ b/arch/s390/kernel/base.S
@@ -76,6 +76,42 @@ s390_base_pgm_handler_fn:
         .quad   0
         .previous
 
+#
+# Calls diag 308 subcode 1 and continues execution
+#
+# The following conditions must be ensured before calling this function:
+# * Prefix register = 0
+# * Lowcore protection is disabled
+#
+ENTRY(diag308_reset)
+        larl    %r4,.Lctlregs           # Save control registers
+        stctg   %c0,%c15,0(%r4)
+        larl    %r4,.Lrestart_psw       # Setup restart PSW at absolute 0
+        lghi    %r3,0
+        lg      %r4,0(%r4)              # Save PSW
+        sturg   %r4,%r3                 # Use sturg, because of large pages
+        lghi    %r1,1
+        diag    %r1,%r1,0x308
+.Lrestart_part2:
+        lhi     %r0,0                   # Load r0 with zero
+        lhi     %r1,2                   # Use mode 2 = ESAME (dump)
+        sigp    %r1,%r0,0x12            # Switch to ESAME mode
+        sam64                           # Switch to 64 bit addressing mode
+        larl    %r4,.Lctlregs           # Restore control registers
+        lctlg   %c0,%c15,0(%r4)
+        br      %r14
+.align 16
+.Lrestart_psw:
+        .long   0x00080000,0x80000000 + .Lrestart_part2
+
+        .section .bss
+.align 8
+.Lctlregs:
+        .rept   16
+        .quad   0
+        .endr
+        .previous
+
 #else /* CONFIG_64BIT */
 
 ENTRY(s390_base_mcck_handler)
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 059c59027ac0..04361d5a4279 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1996,6 +1996,12 @@ static void do_reset_calls(void)
 {
         struct reset_call *reset;
 
+#ifdef CONFIG_64BIT
+        if (diag308_set_works) {
+                diag308_reset();
+                return;
+        }
+#endif
         list_for_each_entry(reset, &rcall, list)
                 reset->fn();
 }