When stop is executed with EC=ESL=0, it appears to execute like a
normal instruction (resuming from NIP when woken by interrupt).
So all the save/restore handling can be avoided completely. In
particular NV GPRs do not have to be saved, and MSR does not have
to be switched back to kernel MSR.
So move the test for "lite" sleep states out to power9_idle_stop.
Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/idle_book3s.S | 35 ++++++++++++++++++++++++-----------
1 file changed, 24 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/kernel/idle_book3s.S
b/arch/powerpc/kernel/idle_book3s.S
index 32d65ee323a0..fa56120bd0bc 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -315,9 +315,6 @@ enter_winkle:
ARCH207_IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
-/*
- * r3 - PSSCR value corresponding to the requested stop state.
- */
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
power_enter_stop_kvm_rm:
/*
@@ -330,14 +327,11 @@ power_enter_stop_kvm_rm:
li r4,KVM_HWTHREAD_IN_IDLE
/* DO THIS IN REAL MODE! See comment above. */
stb r4,HSTATE_HWTHREAD_STATE(r13)
-#endif
-power_enter_stop:
/*
* Check if we are executing the lite variant with ESL=EC=0
*/
- andis. r4,r3,PSSCR_EC_ESL_MASK_SHIFTED
- clrldi r3,r3,60 /* r3 = Bits[60:63] = Requested Level (RL) */
- bne .Lhandle_esl_ec_set
+ andis. r4,r3,PSSCR_EC_ESL_MASK_SHIFTED
+ bne power_enter_stop_esl
PPC_STOP
li r3,0 /* Since we didn't lose state, return 0 */
@@ -354,8 +348,13 @@ power_enter_stop:
*/
li r12, 0
b pnv_wakeup_noloss
+#endif
-.Lhandle_esl_ec_set:
+/*
+ * r3 - PSSCR value corresponding to the requested stop state.
+ */
+power_enter_stop_esl:
+ clrldi r3,r3,60 /* r3 = Bits[60:63] = Requested Level (RL) */
/*
* POWER9 DD2 can incorrectly set PMAO when waking up after a
* state-loss idle. Saving and restoring MMCR0 over idle is a
@@ -428,9 +427,23 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);
\
* r3 contains desired PSSCR register value.
*/
_GLOBAL(power9_idle_stop)
- std r3, PACA_REQ_PSSCR(r13)
mtspr SPRN_PSSCR,r3
- LOAD_REG_ADDR(r4,power_enter_stop)
+
+ /*
+ * Check if we are executing the lite variant with ESL=EC=0
+ * This case resumes execution after the stop instruction without
+ * losing any state, so nothing has to be saved. The following
+ * instructions up to the blr must be skipped if we want to
+ * use power_enter_stop_kvm_rm.
+ */
+ andis. r4,r3,PSSCR_EC_ESL_MASK_SHIFTED
+ bne 1f
+ PPC_STOP
+ li r3,0 /* Since we didn't lose state, return 0 */
+ blr
+1: /* state-loss idle */
+ std r3, PACA_REQ_PSSCR(r13)
+ LOAD_REG_ADDR(r4,power_enter_stop_esl)
b pnv_powersave_common
/* No return */
--
2.13.3
