4 files changed, 89 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/cpuidle.h b/arch/powerpc/include/asm/cpuidle.h
index 52586f9956bb..8a174cba5567 100644
--- a/arch/powerpc/include/asm/cpuidle.h
+++ b/arch/powerpc/include/asm/cpuidle.h
@@ -67,6 +67,17 @@
 #define ERR_DEEP_STATE_ESL_MISMATCH	-2
 
 #ifndef __ASSEMBLY__
+/* Additional SPRs that need to be saved/restored during stop */
+struct stop_sprs {
+	u64 pid;
+	u64 ldbar;
+	u64 fscr;
+	u64 hfscr;
+	u64 mmcr1;
+	u64 mmcr2;
+	u64 mmcra;
+};
+
 extern u32 pnv_fastsleep_workaround_at_entry[];
 extern u32 pnv_fastsleep_workaround_at_exit[];
 
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index dc88a31cc79a..04b60af027ae 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -31,6 +31,7 @@
 #endif
 #include <asm/accounting.h>
 #include <asm/hmi.h>
+#include <asm/cpuidle.h>
 
 register struct paca_struct *local_paca asm("r13");
 
@@ -183,6 +184,12 @@ struct paca_struct {
 	struct paca_struct **thread_sibling_pacas;
 	/* The PSSCR value that the kernel requested before going to stop */
 	u64 requested_psscr;
+
+	/*
+	 * Save area for additional SPRs that need to be
+	 * saved/restored during cpuidle stop.
+	 */
+	struct stop_sprs stop_sprs;
 #endif
 
 #ifdef CONFIG_PPC_STD_MMU_64
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 6e95c2c19a7e..8cfb20e38cfe 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -746,6 +746,14 @@ int main(void)
 	OFFSET(PACA_SUBCORE_SIBLING_MASK, paca_struct, subcore_sibling_mask);
 	OFFSET(PACA_SIBLING_PACA_PTRS, paca_struct, thread_sibling_pacas);
 	OFFSET(PACA_REQ_PSSCR, paca_struct, requested_psscr);
+#define STOP_SPR(x, f)	OFFSET(x, paca_struct, stop_sprs.f)
+	STOP_SPR(STOP_PID, pid);
+	STOP_SPR(STOP_LDBAR, ldbar);
+	STOP_SPR(STOP_FSCR, fscr);
+	STOP_SPR(STOP_HFSCR, hfscr);
+	STOP_SPR(STOP_MMCR1, mmcr1);
+	STOP_SPR(STOP_MMCR2, mmcr2);
+	STOP_SPR(STOP_MMCRA, mmcra);
 #endif
 
 	DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER);
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: