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-rw-r--r--arch/powerpc/kernel/idle_book3s.S65
1 files changed, 63 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 516ebef905c0..4621568277f2 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -85,7 +85,61 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
std r3,_WORT(r1)
mfspr r3,SPRN_WORC
std r3,_WORC(r1)
+/*
+ * On POWER9, there are idle states such as stop4, invoked via cpuidle,
+ * that lose hypervisor resources. In such cases, we need to save
+ * additional SPRs before entering those idle states so that they can
+ * be restored to their older values on wakeup from the idle state.
+ *
+ * On POWER8, the only such deep idle state is winkle which is used
+ * only in the context of CPU-Hotplug, where these additional SPRs are
+ * reinitiazed to a sane value. Hence there is no need to save/restore
+ * these SPRs.
+ */
+BEGIN_FTR_SECTION
+ blr
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
+
+power9_save_additional_sprs:
+ mfspr r3, SPRN_PID
+ mfspr r4, SPRN_LDBAR
+ std r3, STOP_PID(r13)
+ std r4, STOP_LDBAR(r13)
+ mfspr r3, SPRN_FSCR
+ mfspr r4, SPRN_HFSCR
+ std r3, STOP_FSCR(r13)
+ std r4, STOP_HFSCR(r13)
+
+ mfspr r3, SPRN_MMCRA
+ mfspr r4, SPRN_MMCR1
+ std r3, STOP_MMCRA(r13)
+ std r4, STOP_MMCR1(r13)
+
+ mfspr r3, SPRN_MMCR2
+ std r3, STOP_MMCR2(r13)
+ blr
+
+power9_restore_additional_sprs:
+ ld r3,_LPCR(r1)
+ ld r4, STOP_PID(r13)
+ mtspr SPRN_LPCR,r3
+ mtspr SPRN_PID, r4
+
+ ld r3, STOP_LDBAR(r13)
+ ld r4, STOP_FSCR(r13)
+ mtspr SPRN_LDBAR, r3
+ mtspr SPRN_FSCR, r4
+
+ ld r3, STOP_HFSCR(r13)
+ ld r4, STOP_MMCRA(r13)
+ mtspr SPRN_HFSCR, r3
+ mtspr SPRN_MMCRA, r4
+ /* We have already restored PACA_MMCR0 */
+ ld r3, STOP_MMCR1(r13)
+ ld r4, STOP_MMCR2(r13)
+ mtspr SPRN_MMCR1, r3
+ mtspr SPRN_MMCR2, r4
blr
/*
@@ -803,9 +857,16 @@ no_segments:
mtctr r12
bctrl
+/*
+ * On POWER9, we can come here on wakeup from a cpuidle stop state.
+ * Hence restore the additional SPRs to the saved value.
+ *
+ * On POWER8, we come here only on winkle. Since winkle is used
+ * only in the case of CPU-Hotplug, we don't need to restore
+ * the additional SPRs.
+ */
BEGIN_FTR_SECTION
- ld r4,_LPCR(r1)
- mtspr SPRN_LPCR,r4
+ bl power9_restore_additional_sprs
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
hypervisor_state_restored: