[kvm-unit-tests PATCH v4 1/9] s390x: saving regs for interrupts

[Pierre Morel <pmorel@linux.ibm.com>]

If we use multiple source of interrupts, for exemple, using SCLP
console to print information while using I/O interrupts, we need
to have a re-entrant register saving interruption handling.

Instead of saving at a static memory address, let's save the base
registers and the floating point registers on the stack.

Note that we keep the static register saving to recover from the
RESET tests.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 s390x/cstart64.S | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 86dd4c4..ff05f9b 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -118,6 +118,25 @@ memsetxc:
 	lmg	%r0, %r15, GEN_LC_SW_INT_GRS
 	.endm
 
+	.macro SAVE_IRQ_REGS
+	slgfi   %r15, 15 * 8
+	stmg    %r0, %r14, 0(%r15)
+	slgfi   %r15, 16 * 8
+	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	std	\i, \i * 8(%r15)
+	.endr
+	lgr     %r2, %r15
+	.endm
+
+	.macro RESTORE_IRQ_REGS
+	.irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	ld	\i, \i * 8(%r15)
+	.endr
+	algfi   %r15, 16 * 8
+	lmg     %r0, %r14, 0(%r15)
+	algfi   %r15, 15 * 8
+	.endm
+
 .section .text
 /*
  * load_reset calling convention:
@@ -154,6 +173,8 @@ diag308_load_reset:
 	lpswe	GEN_LC_SW_INT_PSW
 1:	br	%r14
 
+
+
 .globl smp_cpu_setup_state
 smp_cpu_setup_state:
 	xgr	%r1, %r1
@@ -180,9 +201,9 @@ mcck_int:
 	lpswe	GEN_LC_MCCK_OLD_PSW
 
 io_int:
-	SAVE_REGS
+	SAVE_IRQ_REGS
 	brasl	%r14, handle_io_int
-	RESTORE_REGS
+	RESTORE_IRQ_REGS
 	lpswe	GEN_LC_IO_OLD_PSW
 
 svc_int:
-- 
2.17.0