[PATCH 5.10 553/717] s390/idle: add missing mt_cycles calculation

Greg Kroah-Hartman
2020-12-28T14:25:52Z

From: Sven Schnelle <svens@linux.ibm.com>

commit e259b3fafa7de362b04ecd86e7fa9a9e9273e5fb upstream.

During removal of the critical section cleanup the calculation
of mt_cycles during idle was removed. This causes invalid
accounting on systems with SMT enabled.

Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S")
Cc: <stable@vger.kernel.org> # 5.8
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/s390/kernel/entry.S | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)

--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -112,7 +112,7 @@ _LPP_OFFSET = __LC_LPP

.macro SWITCH_ASYNC savearea,timer
tmhh %r8,0x0001 # interrupting from user ?
- jnz 2f
+ jnz 4f
#if IS_ENABLED(CONFIG_KVM)
lgr %r14,%r9
larl %r13,.Lsie_gmap
@@ -125,9 +125,25 @@ _LPP_OFFSET = __LC_LPP
#endif
0: larl %r13,.Lpsw_idle_exit
cgr %r13,%r9
- jne 1f
+ jne 3f

- mvc __CLOCK_IDLE_EXIT(8,%r2), __LC_INT_CLOCK
+ larl %r1,smp_cpu_mtid
+ llgf %r1,0(%r1)
+ ltgr %r1,%r1
+ jz 2f # no SMT, skip mt_cycles calculation
+ .insn rsy,0xeb0000000017,%r1,5,__SF_EMPTY+80(%r15)
+ larl %r3,mt_cycles
+ ag %r3,__LC_PERCPU_OFFSET
+ la %r4,__SF_EMPTY+16(%r15)
+1: lg %r0,0(%r3)
+ slg %r0,0(%r4)
+ alg %r0,64(%r4)
+ stg %r0,0(%r3)
+ la %r3,8(%r3)
+ la %r4,8(%r4)
+ brct %r1,1b
+
+2: mvc __CLOCK_IDLE_EXIT(8,%r2), __LC_INT_CLOCK
mvc __TIMER_IDLE_EXIT(8,%r2), __LC_ASYNC_ENTER_TIMER
# account system time going idle
ni __LC_CPU_FLAGS+7,255-_CIF_ENABLED_WAIT
@@ -146,17 +162,17 @@ _LPP_OFFSET = __LC_LPP
mvc __LC_LAST_UPDATE_TIMER(8),__TIMER_IDLE_EXIT(%r2)

nihh %r8,0xfcfd # clear wait state and irq bits
-1: lg %r14,__LC_ASYNC_STACK # are we already on the target stack?
+3: lg %r14,__LC_ASYNC_STACK # are we already on the target stack?
slgr %r14,%r15
srag %r14,%r14,STACK_SHIFT
- jnz 3f
+ jnz 5f
CHECK_STACK \savearea
aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
- j 4f
-2: UPDATE_VTIME %r14,%r15,\timer
+ j 6f
+4: UPDATE_VTIME %r14,%r15,\timer
BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
-3: lg %r15,__LC_ASYNC_STACK # load async stack
-4: la %r11,STACK_FRAME_OVERHEAD(%r15)
+5: lg %r15,__LC_ASYNC_STACK # load async stack
+6: la %r11,STACK_FRAME_OVERHEAD(%r15)
.endm

.macro UPDATE_VTIME w1,w2,enter_timer