[PATCH v2 0/5] Winkle support for offline cpus

[PATCH v2 0/5] Winkle support for offline cpus

[Shreyas B. Prabhu]

Powernv already has support for nap and sleep and these states are used
by cpuidle framework. This patchset adds support for 'deep winkle' a 
deeper idle state. 

In deep winkle, entire chiplet (core/L2/L3) is power off, leading to 
higher power savings. But this results in hypervisor state loss. This
patchset add the necessary infrastructure to recover from hypervisor
state loss and enables offline cpus to use winkle. 

I've successfully tested subcore functionality with these patches. 
Particularly these two scenarios:

Scenario 1:
-> Set subcore-per-core to 4.
-> Offline and online a complete core
Check if core wakes up with 4 subcores

Scenario 2. 
-> Set subcore-per-core to 1.
-> Offline a core. 
-> set subcore-per-core to 4.
-> Online a core 
Check if core wakes up with 4 subcores.

In both these scenarios, the core wakes up with 4 subcores and can run 
guests on individual subcores.

Note, these patches apply on top 'powernv/cpuidle: Fastsleep workaround and
fixes' series.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Srivatsa S. Bhat <srivatsa@MIT.EDU>
Cc: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org

v2:
Rebased on 3.17-rc7
Split from 'powerpc/powernv: Support for fastsleep and winkle'

v1:
https://lkml.org/lkml/2014/8/25/446

Shreyas B. Prabhu (5):
  powerpc/powernv: Add OPAL call to save and restore
  powerpc: Adding macro for accessing Thread Switch Control Register
  powerpc/powernv: Add winkle infrastructure
  powerpc/powernv: Discover and enable winkle
  powerpc/powernv: Enter deepest supported idle state in offline

 arch/powerpc/include/asm/machdep.h             |  1 +
 arch/powerpc/include/asm/opal.h                |  3 +
 arch/powerpc/include/asm/paca.h                |  3 +
 arch/powerpc/include/asm/ppc-opcode.h          |  2 +
 arch/powerpc/include/asm/processor.h           |  2 +
 arch/powerpc/include/asm/reg.h                 |  1 +
 arch/powerpc/kernel/asm-offsets.c              |  1 +
 arch/powerpc/kernel/exceptions-64s.S           |  4 +-
 arch/powerpc/kernel/idle.c                     | 11 +++
 arch/powerpc/kernel/idle_power7.S              | 81 ++++++++++++++++++++-
 arch/powerpc/platforms/powernv/opal-wrappers.S |  1 +
 arch/powerpc/platforms/powernv/powernv.h       |  1 +
 arch/powerpc/platforms/powernv/setup.c         | 99 ++++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/smp.c           |  6 +-
 arch/powerpc/platforms/powernv/subcore.c       | 15 ++++
 15 files changed, 226 insertions(+), 5 deletions(-)

-- 
1.9.3

[PATCH v2 1/5] powerpc/powernv: Add OPAL call to save and restore

[Shreyas B. Prabhu]

PORE can be programmed to restore hypervisor registers when waking up
from deep cpu idle states like winkle.

Add call to pass SPR address and value to OPAL, which in turn will
program PORE to restore the register state.

Cc: linuxppc-dev@lists.ozlabs.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Suggested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/opal.h                | 2 ++
 arch/powerpc/platforms/powernv/opal-wrappers.S | 1 +
 2 files changed, 3 insertions(+)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 166d572..d376020 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -150,6 +150,7 @@ struct opal_sg_list {
 #define OPAL_PCI_EEH_FREEZE_SET			97
 #define OPAL_HANDLE_HMI				98
 #define OPAL_CONFIG_IDLE_STATE			99
+#define OPAL_SLW_SET_REG			100
 #define OPAL_REGISTER_DUMP_REGION		101
 #define OPAL_UNREGISTER_DUMP_REGION		102
 
@@ -978,6 +979,7 @@ extern int opal_handle_hmi_exception(struct pt_regs *regs);
 extern void opal_shutdown(void);
 extern int opal_resync_timebase(void);
 int64_t opal_config_idle_state(uint64_t state, uint64_t enter);
+int64_t opal_slw_set_reg(uint64_t cpu_pir, uint64_t sprn, uint64_t val);
 
 extern void opal_lpc_init(void);
 
diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index 8d1e724..12e5d46 100644
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -246,5 +246,6 @@ OPAL_CALL(opal_get_param,			OPAL_GET_PARAM);
 OPAL_CALL(opal_set_param,			OPAL_SET_PARAM);
 OPAL_CALL(opal_handle_hmi,			OPAL_HANDLE_HMI);
 OPAL_CALL(opal_config_idle_state,		OPAL_CONFIG_IDLE_STATE);
+OPAL_CALL(opal_slw_set_reg,			OPAL_SLW_SET_REG);
 OPAL_CALL(opal_register_dump_region,		OPAL_REGISTER_DUMP_REGION);
 OPAL_CALL(opal_unregister_dump_region,		OPAL_UNREGISTER_DUMP_REGION);
-- 
1.9.3

[PATCH v2 2/5] powerpc: Adding macro for accessing Thread Switch Control Register

[Shreyas B. Prabhu]

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/reg.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 0c05059..cb65a73 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -371,6 +371,7 @@
 #define SPRN_DBAT7L	0x23F	/* Data BAT 7 Lower Register */
 #define SPRN_DBAT7U	0x23E	/* Data BAT 7 Upper Register */
 #define SPRN_PPR	0x380	/* SMT Thread status Register */
+#define SPRN_TSCR	0x399	/* Thread Switch Control Register */
 
 #define SPRN_DEC	0x016		/* Decrement Register */
 #define SPRN_DER	0x095		/* Debug Enable Regsiter */
-- 
1.9.3

[PATCH v2 3/5] powerpc/powernv: Add winkle infrastructure

[Shreyas B. Prabhu]

Winkle causes power to be gated off to the entire chiplet. Hence the
hypervisor/firmware state in the entire chiplet is lost.

This patch adds necessary infrastructure to support waking up from
hypervisor state loss. Specifically does following:
- Before entering winkle, save state of registers that need to be
  restored on wake up (SDR1, HFSCR)

- SRR1 bits 46:47 which is used to identify which power saving mode cpu
  woke up from is '11' for both winkle and sleep. Hence introduce a flag
  in PACA to distinguish b/w winkle and sleep.

- Upon waking up, restore all saved registers, recover slb

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Suggested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/machdep.h     |  1 +
 arch/powerpc/include/asm/paca.h        |  3 ++
 arch/powerpc/include/asm/ppc-opcode.h  |  2 +
 arch/powerpc/include/asm/processor.h   |  2 +
 arch/powerpc/kernel/asm-offsets.c      |  1 +
 arch/powerpc/kernel/exceptions-64s.S   |  8 ++--
 arch/powerpc/kernel/idle.c             | 11 +++++
 arch/powerpc/kernel/idle_power7.S      | 81 +++++++++++++++++++++++++++++++++-
 arch/powerpc/platforms/powernv/setup.c | 24 ++++++++++
 9 files changed, 127 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index f37014f..0a3ced9 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -301,6 +301,7 @@ struct machdep_calls {
 	/* Idle handlers */
 	void		(*setup_idle)(void);
 	unsigned long	(*power7_sleep)(void);
+	unsigned long	(*power7_winkle)(void);
 };
 
 extern void e500_idle(void);
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index a5139ea..3358f09 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -158,6 +158,9 @@ struct paca_struct {
 	 * early exception handler for use by high level C handler
 	 */
 	struct opal_machine_check_event *opal_mc_evt;
+
+	/* Flag to distinguish b/w sleep and winkle */
+	u8 offline_state;
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
 	/* Exclusive emergency stack pointer for machine check exception. */
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 6f85362..5155be7 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -194,6 +194,7 @@
 
 #define PPC_INST_NAP			0x4c000364
 #define PPC_INST_SLEEP			0x4c0003a4
+#define PPC_INST_WINKLE			0x4c0003e4
 
 /* A2 specific instructions */
 #define PPC_INST_ERATWE			0x7c0001a6
@@ -374,6 +375,7 @@
 
 #define PPC_NAP			stringify_in_c(.long PPC_INST_NAP)
 #define PPC_SLEEP		stringify_in_c(.long PPC_INST_SLEEP)
+#define PPC_WINKLE		stringify_in_c(.long PPC_INST_WINKLE)
 
 /* BHRB instructions */
 #define PPC_CLRBHRB		stringify_in_c(.long PPC_INST_CLRBHRB)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 41953cd..00e3df9 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -455,6 +455,8 @@ extern void arch_setup_idle(void);
 extern void power7_nap(int check_irq);
 extern unsigned long power7_sleep(void);
 extern unsigned long __power7_sleep(void);
+extern unsigned long power7_winkle(void);
+extern unsigned long __power7_winkle(void);
 extern void flush_instruction_cache(void);
 extern void hard_reset_now(void);
 extern void poweroff_now(void);
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 9d7dede..ea98817 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -731,6 +731,7 @@ int main(void)
 	DEFINE(OPAL_MC_SRR0, offsetof(struct opal_machine_check_event, srr0));
 	DEFINE(OPAL_MC_SRR1, offsetof(struct opal_machine_check_event, srr1));
 	DEFINE(PACA_OPAL_MC_EVT, offsetof(struct paca_struct, opal_mc_evt));
+	DEFINE(PACAOFFLINESTATE, offsetof(struct paca_struct, offline_state));
 #endif
 
 	return 0;
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index c64f3cc0..261f348 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -115,9 +115,7 @@ BEGIN_FTR_SECTION
 #endif
 
 	/* Running native on arch 2.06 or later, check if we are
-	 * waking up from nap. We only handle no state loss and
-	 * supervisor state loss. We do -not- handle hypervisor
-	 * state loss at this time.
+	 * waking up from power saving mode.
 	 */
 	mfspr	r13,SPRN_SRR1
 	rlwinm.	r13,r13,47-31,30,31
@@ -133,8 +131,8 @@ BEGIN_FTR_SECTION
 	b	power7_wakeup_noloss
 2:	b	power7_wakeup_loss
 
-	/* Fast Sleep wakeup on PowerNV */
-8:	b 	power7_wakeup_tb_loss
+	/* Fast Sleep / Winkle wakeup on PowerNV */
+8:	b 	power7_wakeup_hv_state_loss
 
 9:
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 1f268e0..ed46217 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -98,6 +98,17 @@ unsigned long power7_sleep(void)
 	return ret;
 }
 
+unsigned long power7_winkle(void)
+{
+	unsigned long ret;
+
+	if (ppc_md.power7_winkle)
+		ret = ppc_md.power7_winkle();
+	else
+		ret = __power7_winkle();
+	return ret;
+}
+
 int powersave_nap;
 
 #ifdef CONFIG_SYSCTL
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index c3481c9..87b2556 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -18,6 +18,13 @@
 #include <asm/hw_irq.h>
 #include <asm/kvm_book3s_asm.h>
 #include <asm/opal.h>
+#include <asm/mmu-hash64.h>
+
+/*
+ * Use volatile GPRs' space to save essential SPRs before entering winkle
+ */
+#define _SDR1	GPR3
+#define _TSCR	GPR4
 
 #undef DEBUG
 
@@ -39,6 +46,7 @@
  * Pass requested state in r3:
  * 	0 - nap
  * 	1 - sleep
+ *	2 - winkle
  *
  * To check IRQ_HAPPENED in r4
  * 	0 - don't check
@@ -109,9 +117,27 @@ _GLOBAL(power7_enter_nap_mode)
 #endif
 	cmpwi	cr0,r3,1
 	beq	2f
+	cmpwi	cr0,r3,2
+	beq	3f
 	IDLE_STATE_ENTER_SEQ(PPC_NAP)
 	/* No return */
-2:	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+2:
+	li	r4,1
+	stb	r4,PACAOFFLINESTATE(r13)
+	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+	/* No return */
+
+3:
+	mfspr   r4,SPRN_SDR1
+	std     r4,_SDR1(r1)
+
+	mfspr   r4,SPRN_TSCR
+	std     r4,_TSCR(r1)
+
+	/* Enter winkle */
+        li      r4,0
+        stb     r4,PACAOFFLINESTATE(r13)
+	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
 	/* No return */
 
 _GLOBAL(power7_idle)
@@ -187,6 +213,59 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
 20:	nop;
 
 
+_GLOBAL(__power7_winkle)
+	li	r3,2
+	li	r4,1
+	b	power7_powersave_common
+	/* No return */
+
+_GLOBAL(power7_wakeup_hv_state_loss)
+	/* Check paca flag to diffentiate b/w fast sleep and winkle */
+	lbz	r4,PACAOFFLINESTATE(13)
+	cmpwi	cr0,r4,0
+	bne	power7_wakeup_tb_loss
+
+	ld      r2,PACATOC(r13);
+	ld      r1,PACAR1(r13)
+
+	bl 	__restore_cpu_power8
+
+	/* Time base re-sync */
+	li	r3,OPAL_RESYNC_TIMEBASE
+	bl	opal_call_realmode;
+
+	/* Restore SLB  from PACA */
+	ld	r8,PACA_SLBSHADOWPTR(r13)
+
+	.rept	SLB_NUM_BOLTED
+	li	r3, SLBSHADOW_SAVEAREA
+	LDX_BE	r5, r8, r3
+	addi	r3, r3, 8
+	LDX_BE	r6, r8, r3
+	andis.	r7,r5,SLB_ESID_V@h
+	beq	1f
+	slbmte	r6,r5
+1:	addi	r8,r8,16
+	.endr
+
+	ld      r4,_SDR1(r1)
+	mtspr   SPRN_SDR1,r4
+
+	ld      r4,_TSCR(r1)
+	mtspr   SPRN_TSCR,r4
+
+	REST_NVGPRS(r1)
+	REST_GPR(2, r1)
+	ld      r3,_CCR(r1)
+	ld      r4,_MSR(r1)
+	ld      r5,_NIP(r1)
+	addi    r1,r1,INT_FRAME_SIZE
+	mtcr    r3
+	mfspr   r3,SPRN_SRR1            /* Return SRR1 */
+	mtspr   SPRN_SRR1,r4
+	mtspr   SPRN_SRR0,r5
+	rfid
+
 _GLOBAL(power7_wakeup_tb_loss)
 	ld	r2,PACATOC(r13);
 	ld	r1,PACAR1(r13)
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 9d9a898..f45b52d 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -370,6 +370,29 @@ static unsigned long pnv_power7_sleep(void)
 	return srr1;
 }
 
+/*
+ * We need to keep track of offline cpus also for calling
+ * fastsleep workaround appropriately
+ */
+static unsigned long pnv_power7_winkle(void)
+{
+	int cpu, primary_thread;
+	unsigned long srr1;
+
+	cpu = smp_processor_id();
+	primary_thread = cpu_first_thread_sibling(cpu);
+
+	if (need_fastsleep_workaround) {
+		pnv_apply_fastsleep_workaround(1, primary_thread);
+		srr1 = __power7_winkle();
+		pnv_apply_fastsleep_workaround(0, primary_thread);
+	} else {
+			srr1 = __power7_winkle();
+	}
+	return srr1;
+}
+
+
 static void __init pnv_setup_machdep_opal(void)
 {
 	ppc_md.get_boot_time = opal_get_boot_time;
@@ -384,6 +407,7 @@ static void __init pnv_setup_machdep_opal(void)
 	ppc_md.handle_hmi_exception = opal_handle_hmi_exception;
 	ppc_md.setup_idle = pnv_setup_idle;
 	ppc_md.power7_sleep = pnv_power7_sleep;
+	ppc_md.power7_winkle = pnv_power7_winkle;
 }
 
 #ifdef CONFIG_PPC_POWERNV_RTAS
-- 
1.9.3

[PATCH v2 4/5] powerpc/powernv: Discover and enable winkle

[Shreyas B. Prabhu]

Discover winkle from device tree. If supported make OPAL calls
necessary to save HIDs, HMEER, HSPRG0 and LPCR.
Also make OPAL call when the HID0 value is modified during
split/unsplit of cores.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/opal.h          |  1 +
 arch/powerpc/platforms/powernv/powernv.h |  1 +
 arch/powerpc/platforms/powernv/setup.c   | 75 ++++++++++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/subcore.c | 15 +++++++
 4 files changed, 92 insertions(+)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index d376020..a77957f 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -778,6 +778,7 @@ extern struct device_node *opal_node;
 #define IDLE_INST_NAP	0x00010000 /* nap instruction can be used */
 #define IDLE_INST_SLEEP	0x00020000 /* sleep instruction can be used */
 #define IDLE_INST_SLEEP_ER1	0x00080000 /* Use sleep with work around*/
+#define IDLE_INST_WINKLE	0x00040000 /* winkle instruction can be used */
 
 /* API functions */
 int64_t opal_invalid_call(void);
diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index 31ece13..76b37f8 100644
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -27,6 +27,7 @@ static inline int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask)
 
 #define IDLE_USE_NAP		(1UL << 0)
 #define IDLE_USE_SLEEP		(1UL << 1)
+#define IDLE_USE_WINKLE                (1UL << 3)
 
 extern unsigned int pnv_get_supported_cpuidle_states(void);
 
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index f45b52d..13c5e49 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -273,6 +273,65 @@ unsigned int pnv_get_supported_cpuidle_states(void)
 	return supported_cpuidle_states;
 }
 
+int pnv_save_sprs_for_winkle(void)
+{
+	int cpu;
+	int rc;
+
+	/*
+	* hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric accross
+	* all cpus at boot. Get these reg values of current cpu and use the
+	* same accross all cpus.
+	*/
+	uint64_t lpcr_val = mfspr(SPRN_LPCR);
+	uint64_t hid0_val = mfspr(SPRN_HID0);
+	uint64_t hid1_val = mfspr(SPRN_HID1);
+	uint64_t hid4_val = mfspr(SPRN_HID4);
+	uint64_t hid5_val = mfspr(SPRN_HID5);
+	uint64_t hmeer_val = mfspr(SPRN_HMEER);
+
+	for_each_possible_cpu(cpu) {
+		uint64_t pir = get_hard_smp_processor_id(cpu);
+		uint64_t local_paca_ptr = (uint64_t)&paca[cpu];
+
+		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, local_paca_ptr);
+		if (rc != 0)
+			return rc;
+
+		rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
+		if (rc != 0)
+			return rc;
+
+		/* HIDs are per core registers */
+		if (cpu_thread_in_core(cpu) == 0) {
+
+			rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
+			if (rc != 0)
+				return rc;
+
+			rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
+			if (rc != 0)
+				return rc;
+
+		}
+
+	}
+
+	return 0;
+
+}
 static int __init pnv_probe_idle_states(void)
 {
 	struct device_node *power_mgt;
@@ -318,6 +377,22 @@ static int __init pnv_probe_idle_states(void)
 			supported_cpuidle_states |= IDLE_USE_SLEEP;
 			need_fastsleep_workaround = 1;
 		}
+
+		if (flags & IDLE_INST_WINKLE) {
+			/*
+			 * If winkle is supported, save HSPRG0, HIDs and LPCR
+			 * contents via OPAL. Enable winkle only if this
+			 * succeeds.
+			 */
+			int opal_ret_val = pnv_save_sprs_for_winkle();
+
+			if (!opal_ret_val)
+				supported_cpuidle_states |= IDLE_USE_WINKLE;
+			else
+				pr_warn("opal: opal_slw_set_reg failed with rc=%d, disabling winkle\n",
+						opal_ret_val);
+		}
+
 	}
 
 	return 0;
diff --git a/arch/powerpc/platforms/powernv/subcore.c b/arch/powerpc/platforms/powernv/subcore.c
index 894ecb3..47c70666e 100644
--- a/arch/powerpc/platforms/powernv/subcore.c
+++ b/arch/powerpc/platforms/powernv/subcore.c
@@ -24,6 +24,7 @@
 #include <asm/smp.h>
 
 #include "subcore.h"
+#include "powernv.h"
 
 
 /*
@@ -159,6 +160,18 @@ static void wait_for_sync_step(int step)
 	mb();
 }
 
+static void update_hid_in_slw(u64 hid0)
+{
+	u64 idle_states = pnv_get_supported_cpuidle_states();
+
+	if (idle_states & IDLE_USE_WINKLE) {
+		/* OPAL call to patch slw with the new HID0 value */
+		u64 cpu_pir = hard_smp_processor_id();
+
+		opal_slw_set_reg(cpu_pir, SPRN_HID0, hid0);
+	}
+}
+
 static void unsplit_core(void)
 {
 	u64 hid0, mask;
@@ -178,6 +191,7 @@ static void unsplit_core(void)
 	hid0 = mfspr(SPRN_HID0);
 	hid0 &= ~HID0_POWER8_DYNLPARDIS;
 	mtspr(SPRN_HID0, hid0);
+	update_hid_in_slw(hid0);
 
 	while (mfspr(SPRN_HID0) & mask)
 		cpu_relax();
@@ -214,6 +228,7 @@ static void split_core(int new_mode)
 	hid0  = mfspr(SPRN_HID0);
 	hid0 |= HID0_POWER8_DYNLPARDIS | split_parms[i].value;
 	mtspr(SPRN_HID0, hid0);
+	update_hid_in_slw(hid0);
 
 	/* Wait for it to happen */
 	while (!(mfspr(SPRN_HID0) & split_parms[i].mask))
-- 
1.9.3

[PATCH v2 5/5] powerpc/powernv: Enter deepest supported idle state in offline

[Shreyas B. Prabhu]

Enter winkle during offline if supported, else revert to sleep or nap.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/smp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 3ad31d2..e3fc2c9 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -169,8 +169,10 @@ static void pnv_smp_cpu_kill_self(void)
 	while (!generic_check_cpu_restart(cpu)) {
 		ppc64_runlatch_off();
 
-		/* If sleep is supported, go to sleep, instead of nap */
-		if (idle_states & IDLE_USE_SLEEP)
+		/* Go to deepest supported idle state */
+		if (idle_states & IDLE_USE_WINKLE)
+			power7_winkle();
+		else if (idle_states & IDLE_USE_SLEEP)
 			power7_sleep();
 		else
 			power7_nap(1);
-- 
1.9.3

Re: [PATCH v2 1/5] powerpc/powernv: Add OPAL call to save and restore

[Benjamin Herrenschmidt]

On Wed, 2014-10-01 at 13:16 +0530, Shreyas B. Prabhu wrote:
> PORE can be programmed to restore hypervisor registers when waking up
> from deep cpu idle states like winkle.

Tell us a bit more about what "PORE" is. IE, explain a tiny engine will
reconfigure the core and its ucode can be patched to provide some
registers with sane values.

> Add call to pass SPR address and value to OPAL, which in turn will
> program PORE to restore the register state.

Otherwise, Acke-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Suggested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
> Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/opal.h                | 2 ++
>  arch/powerpc/platforms/powernv/opal-wrappers.S | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index 166d572..d376020 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -150,6 +150,7 @@ struct opal_sg_list {
>  #define OPAL_PCI_EEH_FREEZE_SET			97
>  #define OPAL_HANDLE_HMI				98
>  #define OPAL_CONFIG_IDLE_STATE			99
> +#define OPAL_SLW_SET_REG			100
>  #define OPAL_REGISTER_DUMP_REGION		101
>  #define OPAL_UNREGISTER_DUMP_REGION		102
>  
> @@ -978,6 +979,7 @@ extern int opal_handle_hmi_exception(struct pt_regs *regs);
>  extern void opal_shutdown(void);
>  extern int opal_resync_timebase(void);
>  int64_t opal_config_idle_state(uint64_t state, uint64_t enter);
> +int64_t opal_slw_set_reg(uint64_t cpu_pir, uint64_t sprn, uint64_t val);
>  
>  extern void opal_lpc_init(void);
>  
> diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
> index 8d1e724..12e5d46 100644
> --- a/arch/powerpc/platforms/powernv/opal-wrappers.S
> +++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
> @@ -246,5 +246,6 @@ OPAL_CALL(opal_get_param,			OPAL_GET_PARAM);
>  OPAL_CALL(opal_set_param,			OPAL_SET_PARAM);
>  OPAL_CALL(opal_handle_hmi,			OPAL_HANDLE_HMI);
>  OPAL_CALL(opal_config_idle_state,		OPAL_CONFIG_IDLE_STATE);
> +OPAL_CALL(opal_slw_set_reg,			OPAL_SLW_SET_REG);
>  OPAL_CALL(opal_register_dump_region,		OPAL_REGISTER_DUMP_REGION);
>  OPAL_CALL(opal_unregister_dump_region,		OPAL_UNREGISTER_DUMP_REGION);

Re: [PATCH v2 2/5] powerpc: Adding macro for accessing Thread Switch Control Register

[Benjamin Herrenschmidt]

Just fold that one in the patch that uses that register

On Wed, 2014-10-01 at 13:16 +0530, Shreyas B. Prabhu wrote:
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/reg.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
> index 0c05059..cb65a73 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -371,6 +371,7 @@
>  #define SPRN_DBAT7L	0x23F	/* Data BAT 7 Lower Register */
>  #define SPRN_DBAT7U	0x23E	/* Data BAT 7 Upper Register */
>  #define SPRN_PPR	0x380	/* SMT Thread status Register */
> +#define SPRN_TSCR	0x399	/* Thread Switch Control Register */
>  
>  #define SPRN_DEC	0x016		/* Decrement Register */
>  #define SPRN_DER	0x095		/* Debug Enable Regsiter */

Re: [PATCH v2 3/5] powerpc/powernv: Add winkle infrastructure

[Benjamin Herrenschmidt]

On Wed, 2014-10-01 at 13:16 +0530, Shreyas B. Prabhu wrote:
> Winkle causes power to be gated off to the entire chiplet. Hence the
> hypervisor/firmware state in the entire chiplet is lost.
> 
> This patch adds necessary infrastructure to support waking up from
> hypervisor state loss. Specifically does following:
> - Before entering winkle, save state of registers that need to be
>   restored on wake up (SDR1, HFSCR)

 Add ... to your list, it's not exhaustive, is it ?

> - SRR1 bits 46:47 which is used to identify which power saving mode cpu
>   woke up from is '11' for both winkle and sleep. Hence introduce a flag
>   in PACA to distinguish b/w winkle and sleep.
> 
> - Upon waking up, restore all saved registers, recover slb
> 
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: linuxppc-dev@lists.ozlabs.org
> Suggested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
> Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/machdep.h     |  1 +
>  arch/powerpc/include/asm/paca.h        |  3 ++
>  arch/powerpc/include/asm/ppc-opcode.h  |  2 +
>  arch/powerpc/include/asm/processor.h   |  2 +
>  arch/powerpc/kernel/asm-offsets.c      |  1 +
>  arch/powerpc/kernel/exceptions-64s.S   |  8 ++--
>  arch/powerpc/kernel/idle.c             | 11 +++++
>  arch/powerpc/kernel/idle_power7.S      | 81 +++++++++++++++++++++++++++++++++-
>  arch/powerpc/platforms/powernv/setup.c | 24 ++++++++++
>  9 files changed, 127 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
> index f37014f..0a3ced9 100644
> --- a/arch/powerpc/include/asm/machdep.h
> +++ b/arch/powerpc/include/asm/machdep.h
> @@ -301,6 +301,7 @@ struct machdep_calls {
>  	/* Idle handlers */
>  	void		(*setup_idle)(void);
>  	unsigned long	(*power7_sleep)(void);
> +	unsigned long	(*power7_winkle)(void);
>  };

Why does it need to be ppc_md ? Same comments as for sleep
 
>  extern void e500_idle(void);
> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
> index a5139ea..3358f09 100644
> --- a/arch/powerpc/include/asm/paca.h
> +++ b/arch/powerpc/include/asm/paca.h
> @@ -158,6 +158,9 @@ struct paca_struct {
>  	 * early exception handler for use by high level C handler
>  	 */
>  	struct opal_machine_check_event *opal_mc_evt;
> +
> +	/* Flag to distinguish b/w sleep and winkle */
> +	u8 offline_state;

Not fan of the name. I'd rather you call it "wakeup_state_loss" or
something a bit more explicit about what that actually means if it's
going to be a boolean value. Otherwise make it an enumeration of
constants.

>  #endif
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	/* Exclusive emergency stack pointer for machine check exception. */
> diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
> index 6f85362..5155be7 100644
> --- a/arch/powerpc/include/asm/ppc-opcode.h
> +++ b/arch/powerpc/include/asm/ppc-opcode.h
> @@ -194,6 +194,7 @@
>  
>  #define PPC_INST_NAP			0x4c000364
>  #define PPC_INST_SLEEP			0x4c0003a4
> +#define PPC_INST_WINKLE			0x4c0003e4
>  
>  /* A2 specific instructions */
>  #define PPC_INST_ERATWE			0x7c0001a6
> @@ -374,6 +375,7 @@
>  
>  #define PPC_NAP			stringify_in_c(.long PPC_INST_NAP)
>  #define PPC_SLEEP		stringify_in_c(.long PPC_INST_SLEEP)
> +#define PPC_WINKLE		stringify_in_c(.long PPC_INST_WINKLE)
>  
>  /* BHRB instructions */
>  #define PPC_CLRBHRB		stringify_in_c(.long PPC_INST_CLRBHRB)
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index 41953cd..00e3df9 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -455,6 +455,8 @@ extern void arch_setup_idle(void);
>  extern void power7_nap(int check_irq);
>  extern unsigned long power7_sleep(void);
>  extern unsigned long __power7_sleep(void);
> +extern unsigned long power7_winkle(void);
> +extern unsigned long __power7_winkle(void);
>  extern void flush_instruction_cache(void);
>  extern void hard_reset_now(void);
>  extern void poweroff_now(void);
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 9d7dede..ea98817 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -731,6 +731,7 @@ int main(void)
>  	DEFINE(OPAL_MC_SRR0, offsetof(struct opal_machine_check_event, srr0));
>  	DEFINE(OPAL_MC_SRR1, offsetof(struct opal_machine_check_event, srr1));
>  	DEFINE(PACA_OPAL_MC_EVT, offsetof(struct paca_struct, opal_mc_evt));
> +	DEFINE(PACAOFFLINESTATE, offsetof(struct paca_struct, offline_state));
>  #endif
>  
>  	return 0;
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index c64f3cc0..261f348 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -115,9 +115,7 @@ BEGIN_FTR_SECTION
>  #endif
>  
>  	/* Running native on arch 2.06 or later, check if we are
> -	 * waking up from nap. We only handle no state loss and
> -	 * supervisor state loss. We do -not- handle hypervisor
> -	 * state loss at this time.
> +	 * waking up from power saving mode.
>  	 */
>  	mfspr	r13,SPRN_SRR1
>  	rlwinm.	r13,r13,47-31,30,31
> @@ -133,8 +131,8 @@ BEGIN_FTR_SECTION
>  	b	power7_wakeup_noloss
>  2:	b	power7_wakeup_loss
>  
> -	/* Fast Sleep wakeup on PowerNV */
> -8:	b 	power7_wakeup_tb_loss
> +	/* Fast Sleep / Winkle wakeup on PowerNV */
> +8:	b 	power7_wakeup_hv_state_loss
>  
>  9:
>  END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
> diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
> index 1f268e0..ed46217 100644
> --- a/arch/powerpc/kernel/idle.c
> +++ b/arch/powerpc/kernel/idle.c
> @@ -98,6 +98,17 @@ unsigned long power7_sleep(void)
>  	return ret;
>  }
>  
> +unsigned long power7_winkle(void)
> +{
> +	unsigned long ret;
> +
> +	if (ppc_md.power7_winkle)
> +		ret = ppc_md.power7_winkle();
> +	else
> +		ret = __power7_winkle();
> +	return ret;
> +}
> +
>  int powersave_nap;
>  
>  #ifdef CONFIG_SYSCTL
> diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
> index c3481c9..87b2556 100644
> --- a/arch/powerpc/kernel/idle_power7.S
> +++ b/arch/powerpc/kernel/idle_power7.S
> @@ -18,6 +18,13 @@
>  #include <asm/hw_irq.h>
>  #include <asm/kvm_book3s_asm.h>
>  #include <asm/opal.h>
> +#include <asm/mmu-hash64.h>
> +
> +/*
> + * Use volatile GPRs' space to save essential SPRs before entering winkle
> + */
> +#define _SDR1	GPR3
> +#define _TSCR	GPR4
>  
>  #undef DEBUG
>  
> @@ -39,6 +46,7 @@
>   * Pass requested state in r3:
>   * 	0 - nap
>   * 	1 - sleep
> + *	2 - winkle
>   *
>   * To check IRQ_HAPPENED in r4
>   * 	0 - don't check
> @@ -109,9 +117,27 @@ _GLOBAL(power7_enter_nap_mode)
>  #endif
>  	cmpwi	cr0,r3,1
>  	beq	2f
> +	cmpwi	cr0,r3,2
> +	beq	3f
>  	IDLE_STATE_ENTER_SEQ(PPC_NAP)
>  	/* No return */
> -2:	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
> +2:
> +	li	r4,1
> +	stb	r4,PACAOFFLINESTATE(r13)
> +	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
> +	/* No return */
> +
> +3:
> +	mfspr   r4,SPRN_SDR1
> +	std     r4,_SDR1(r1)
> +
> +	mfspr   r4,SPRN_TSCR
> +	std     r4,_TSCR(r1)
> +
> +	/* Enter winkle */
> +        li      r4,0
> +        stb     r4,PACAOFFLINESTATE(r13)
> +	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
>  	/* No return */
>  
>  _GLOBAL(power7_idle)
> @@ -187,6 +213,59 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
>  20:	nop;
>  
> 
> +_GLOBAL(__power7_winkle)
> +	li	r3,2
> +	li	r4,1
> +	b	power7_powersave_common
> +	/* No return */
> +
> +_GLOBAL(power7_wakeup_hv_state_loss)
> +	/* Check paca flag to diffentiate b/w fast sleep and winkle */
> +	lbz	r4,PACAOFFLINESTATE(13)
> +	cmpwi	cr0,r4,0
> +	bne	power7_wakeup_tb_loss
> +
> +	ld      r2,PACATOC(r13);
> +	ld      r1,PACAR1(r13)
> +
> +	bl 	__restore_cpu_power8

So if I understand correctly, you use a per-cpu flag not a per-core flag
which means we will assume a pessimistic case of having to restore stuff
even if the core didn't actually enter winkle (because the last thread
to go down went to sleep). This is sub-optimal. Also see below:

> +	/* Time base re-sync */
> +	li	r3,OPAL_RESYNC_TIMEBASE
> +	bl	opal_call_realmode;

You will also resync the timebase (and restore all the core shared SPRs)
for each thread. This is problematic, especially with KVM as you could
have a situation where:

 - The first thread comes out and starts diving into KVM

 - The other threads start coming out while the first one is doing the
above.

Thus the first thread might already be manipulating some core registers
(SDR1 etc...) while the secondaries come back and ... whack it. Worse,
the primary might have applied the TB offset using TBU40 while the
secondaries resync the timebase back to the host value, incurring a
loss of TB for the guest.

> +	/* Restore SLB  from PACA */
> +	ld	r8,PACA_SLBSHADOWPTR(r13)
> +
> +	.rept	SLB_NUM_BOLTED
> +	li	r3, SLBSHADOW_SAVEAREA
> +	LDX_BE	r5, r8, r3
> +	addi	r3, r3, 8
> +	LDX_BE	r6, r8, r3
> +	andis.	r7,r5,SLB_ESID_V@h
> +	beq	1f
> +	slbmte	r6,r5
> +1:	addi	r8,r8,16
> +	.endr
> +
> +	ld      r4,_SDR1(r1)
> +	mtspr   SPRN_SDR1,r4
> +
> +	ld      r4,_TSCR(r1)
> +	mtspr   SPRN_TSCR,r4
> +
> +	REST_NVGPRS(r1)
> +	REST_GPR(2, r1)
> +	ld      r3,_CCR(r1)
> +	ld      r4,_MSR(r1)
> +	ld      r5,_NIP(r1)
> +	addi    r1,r1,INT_FRAME_SIZE
> +	mtcr    r3
> +	mfspr   r3,SPRN_SRR1            /* Return SRR1 */
> +	mtspr   SPRN_SRR1,r4
> +	mtspr   SPRN_SRR0,r5
> +	rfid
> +
>  _GLOBAL(power7_wakeup_tb_loss)
>  	ld	r2,PACATOC(r13);
>  	ld	r1,PACAR1(r13)
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index 9d9a898..f45b52d 100644
> --- a/arch/powerpc/platforms/powernv/setup.c
> +++ b/arch/powerpc/platforms/powernv/setup.c
> @@ -370,6 +370,29 @@ static unsigned long pnv_power7_sleep(void)
>  	return srr1;
>  }
>  
> +/*
> + * We need to keep track of offline cpus also for calling
> + * fastsleep workaround appropriately
> + */
> +static unsigned long pnv_power7_winkle(void)
> +{
> +	int cpu, primary_thread;
> +	unsigned long srr1;
> +
> +	cpu = smp_processor_id();
> +	primary_thread = cpu_first_thread_sibling(cpu);
> +
> +	if (need_fastsleep_workaround) {
> +		pnv_apply_fastsleep_workaround(1, primary_thread);
> +		srr1 = __power7_winkle();
> +		pnv_apply_fastsleep_workaround(0, primary_thread);
> +	} else {
> +			srr1 = __power7_winkle();
> +	}
> +	return srr1;
> +}
> +
> +
>  static void __init pnv_setup_machdep_opal(void)
>  {
>  	ppc_md.get_boot_time = opal_get_boot_time;
> @@ -384,6 +407,7 @@ static void __init pnv_setup_machdep_opal(void)
>  	ppc_md.handle_hmi_exception = opal_handle_hmi_exception;
>  	ppc_md.setup_idle = pnv_setup_idle;
>  	ppc_md.power7_sleep = pnv_power7_sleep;
> +	ppc_md.power7_winkle = pnv_power7_winkle;
>  }
>  
>  #ifdef CONFIG_PPC_POWERNV_RTAS

Re: [PATCH v2 3/5] powerpc/powernv: Add winkle infrastructure

[Shreyas B Prabhu]

On Tuesday 07 October 2014 11:03 AM, Benjamin Herrenschmidt wrote:
> On Wed, 2014-10-01 at 13:16 +0530, Shreyas B. Prabhu wrote:
>> Winkle causes power to be gated off to the entire chiplet. Hence the
>> hypervisor/firmware state in the entire chiplet is lost.
>>
>> This patch adds necessary infrastructure to support waking up from
>> hypervisor state loss. Specifically does following:
>> - Before entering winkle, save state of registers that need to be
>>   restored on wake up (SDR1, HFSCR)
> 
>  Add ... to your list, it's not exhaustive, is it ?

I use interrupt stack frame for only SDR1 and HFSCR. The rest of the
SPRs are restored via PORE in the next patch. I'll change the comments
to better reflect this.

> 
>> - SRR1 bits 46:47 which is used to identify which power saving mode cpu
>>   woke up from is '11' for both winkle and sleep. Hence introduce a flag
>>   in PACA to distinguish b/w winkle and sleep.
>>
>> - Upon waking up, restore all saved registers, recover slb
>>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Suggested-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
>> Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
>> ---
>>  arch/powerpc/include/asm/machdep.h     |  1 +
>>  arch/powerpc/include/asm/paca.h        |  3 ++
>>  arch/powerpc/include/asm/ppc-opcode.h  |  2 +
>>  arch/powerpc/include/asm/processor.h   |  2 +
>>  arch/powerpc/kernel/asm-offsets.c      |  1 +
>>  arch/powerpc/kernel/exceptions-64s.S   |  8 ++--
>>  arch/powerpc/kernel/idle.c             | 11 +++++
>>  arch/powerpc/kernel/idle_power7.S      | 81 +++++++++++++++++++++++++++++++++-
>>  arch/powerpc/platforms/powernv/setup.c | 24 ++++++++++
>>  9 files changed, 127 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
>> index f37014f..0a3ced9 100644
>> --- a/arch/powerpc/include/asm/machdep.h
>> +++ b/arch/powerpc/include/asm/machdep.h
>> @@ -301,6 +301,7 @@ struct machdep_calls {
>>  	/* Idle handlers */
>>  	void		(*setup_idle)(void);
>>  	unsigned long	(*power7_sleep)(void);
>> +	unsigned long	(*power7_winkle)(void);
>>  };
> 
> Why does it need to be ppc_md ? Same comments as for sleep
> 
>>  extern void e500_idle(void);
>> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
>> index a5139ea..3358f09 100644
>> --- a/arch/powerpc/include/asm/paca.h
>> +++ b/arch/powerpc/include/asm/paca.h
>> @@ -158,6 +158,9 @@ struct paca_struct {
>>  	 * early exception handler for use by high level C handler
>>  	 */
>>  	struct opal_machine_check_event *opal_mc_evt;
>> +
>> +	/* Flag to distinguish b/w sleep and winkle */
>> +	u8 offline_state;
> 
> Not fan of the name. I'd rather you call it "wakeup_state_loss" or
> something a bit more explicit about what that actually means if it's
> going to be a boolean value. Otherwise make it an enumeration of
> constants.
> 
Okay. I'll change this.

>>  #endif
>>  #ifdef CONFIG_PPC_BOOK3S_64
>>  	/* Exclusive emergency stack pointer for machine check exception. */
>> diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
>> index 6f85362..5155be7 100644
>> --- a/arch/powerpc/include/asm/ppc-opcode.h
>> +++ b/arch/powerpc/include/asm/ppc-opcode.h
>> @@ -194,6 +194,7 @@
>>  
>>  #define PPC_INST_NAP			0x4c000364
>>  #define PPC_INST_SLEEP			0x4c0003a4
>> +#define PPC_INST_WINKLE			0x4c0003e4
>>  
>>  /* A2 specific instructions */
>>  #define PPC_INST_ERATWE			0x7c0001a6
>> @@ -374,6 +375,7 @@
>>  
>>  #define PPC_NAP			stringify_in_c(.long PPC_INST_NAP)
>>  #define PPC_SLEEP		stringify_in_c(.long PPC_INST_SLEEP)
>> +#define PPC_WINKLE		stringify_in_c(.long PPC_INST_WINKLE)
>>  
>>  /* BHRB instructions */
>>  #define PPC_CLRBHRB		stringify_in_c(.long PPC_INST_CLRBHRB)
>> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
>> index 41953cd..00e3df9 100644
>> --- a/arch/powerpc/include/asm/processor.h
>> +++ b/arch/powerpc/include/asm/processor.h
>> @@ -455,6 +455,8 @@ extern void arch_setup_idle(void);
>>  extern void power7_nap(int check_irq);
>>  extern unsigned long power7_sleep(void);
>>  extern unsigned long __power7_sleep(void);
>> +extern unsigned long power7_winkle(void);
>> +extern unsigned long __power7_winkle(void);
>>  extern void flush_instruction_cache(void);
>>  extern void hard_reset_now(void);
>>  extern void poweroff_now(void);
>> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
>> index 9d7dede..ea98817 100644
>> --- a/arch/powerpc/kernel/asm-offsets.c
>> +++ b/arch/powerpc/kernel/asm-offsets.c
>> @@ -731,6 +731,7 @@ int main(void)
>>  	DEFINE(OPAL_MC_SRR0, offsetof(struct opal_machine_check_event, srr0));
>>  	DEFINE(OPAL_MC_SRR1, offsetof(struct opal_machine_check_event, srr1));
>>  	DEFINE(PACA_OPAL_MC_EVT, offsetof(struct paca_struct, opal_mc_evt));
>> +	DEFINE(PACAOFFLINESTATE, offsetof(struct paca_struct, offline_state));
>>  #endif
>>  
>>  	return 0;
>> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
>> index c64f3cc0..261f348 100644
>> --- a/arch/powerpc/kernel/exceptions-64s.S
>> +++ b/arch/powerpc/kernel/exceptions-64s.S
>> @@ -115,9 +115,7 @@ BEGIN_FTR_SECTION
>>  #endif
>>  
>>  	/* Running native on arch 2.06 or later, check if we are
>> -	 * waking up from nap. We only handle no state loss and
>> -	 * supervisor state loss. We do -not- handle hypervisor
>> -	 * state loss at this time.
>> +	 * waking up from power saving mode.
>>  	 */
>>  	mfspr	r13,SPRN_SRR1
>>  	rlwinm.	r13,r13,47-31,30,31
>> @@ -133,8 +131,8 @@ BEGIN_FTR_SECTION
>>  	b	power7_wakeup_noloss
>>  2:	b	power7_wakeup_loss
>>  
>> -	/* Fast Sleep wakeup on PowerNV */
>> -8:	b 	power7_wakeup_tb_loss
>> +	/* Fast Sleep / Winkle wakeup on PowerNV */
>> +8:	b 	power7_wakeup_hv_state_loss
>>  
>>  9:
>>  END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
>> diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
>> index 1f268e0..ed46217 100644
>> --- a/arch/powerpc/kernel/idle.c
>> +++ b/arch/powerpc/kernel/idle.c
>> @@ -98,6 +98,17 @@ unsigned long power7_sleep(void)
>>  	return ret;
>>  }
>>  
>> +unsigned long power7_winkle(void)
>> +{
>> +	unsigned long ret;
>> +
>> +	if (ppc_md.power7_winkle)
>> +		ret = ppc_md.power7_winkle();
>> +	else
>> +		ret = __power7_winkle();
>> +	return ret;
>> +}
>> +
>>  int powersave_nap;
>>  
>>  #ifdef CONFIG_SYSCTL
>> diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
>> index c3481c9..87b2556 100644
>> --- a/arch/powerpc/kernel/idle_power7.S
>> +++ b/arch/powerpc/kernel/idle_power7.S
>> @@ -18,6 +18,13 @@
>>  #include <asm/hw_irq.h>
>>  #include <asm/kvm_book3s_asm.h>
>>  #include <asm/opal.h>
>> +#include <asm/mmu-hash64.h>
>> +
>> +/*
>> + * Use volatile GPRs' space to save essential SPRs before entering winkle
>> + */
>> +#define _SDR1	GPR3
>> +#define _TSCR	GPR4
>>  
>>  #undef DEBUG
>>  
>> @@ -39,6 +46,7 @@
>>   * Pass requested state in r3:
>>   * 	0 - nap
>>   * 	1 - sleep
>> + *	2 - winkle
>>   *
>>   * To check IRQ_HAPPENED in r4
>>   * 	0 - don't check
>> @@ -109,9 +117,27 @@ _GLOBAL(power7_enter_nap_mode)
>>  #endif
>>  	cmpwi	cr0,r3,1
>>  	beq	2f
>> +	cmpwi	cr0,r3,2
>> +	beq	3f
>>  	IDLE_STATE_ENTER_SEQ(PPC_NAP)
>>  	/* No return */
>> -2:	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
>> +2:
>> +	li	r4,1
>> +	stb	r4,PACAOFFLINESTATE(r13)
>> +	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
>> +	/* No return */
>> +
>> +3:
>> +	mfspr   r4,SPRN_SDR1
>> +	std     r4,_SDR1(r1)
>> +
>> +	mfspr   r4,SPRN_TSCR
>> +	std     r4,_TSCR(r1)
>> +
>> +	/* Enter winkle */
>> +        li      r4,0
>> +        stb     r4,PACAOFFLINESTATE(r13)
>> +	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
>>  	/* No return */
>>  
>>  _GLOBAL(power7_idle)
>> @@ -187,6 +213,59 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
>>  20:	nop;
>>  
>>
>> +_GLOBAL(__power7_winkle)
>> +	li	r3,2
>> +	li	r4,1
>> +	b	power7_powersave_common
>> +	/* No return */
>> +
>> +_GLOBAL(power7_wakeup_hv_state_loss)
>> +	/* Check paca flag to diffentiate b/w fast sleep and winkle */
>> +	lbz	r4,PACAOFFLINESTATE(13)
>> +	cmpwi	cr0,r4,0
>> +	bne	power7_wakeup_tb_loss
>> +
>> +	ld      r2,PACATOC(r13);
>> +	ld      r1,PACAR1(r13)
>> +
>> +	bl 	__restore_cpu_power8
> 
> So if I understand correctly, you use a per-cpu flag not a per-core flag
> which means we will assume a pessimistic case of having to restore stuff
> even if the core didn't actually enter winkle (because the last thread
> to go down went to sleep). This is sub-optimal. Also see below:
> 
>> +	/* Time base re-sync */
>> +	li	r3,OPAL_RESYNC_TIMEBASE
>> +	bl	opal_call_realmode;
> 
> You will also resync the timebase (and restore all the core shared SPRs)
> for each thread. This is problematic, especially with KVM as you could
> have a situation where:
> 
>  - The first thread comes out and starts diving into KVM
> 
>  - The other threads start coming out while the first one is doing the
> above.
> 
> Thus the first thread might already be manipulating some core registers
> (SDR1 etc...) while the secondaries come back and ... whack it. Worse,
> the primary might have applied the TB offset using TBU40 while the
> secondaries resync the timebase back to the host value, incurring a
> loss of TB for the guest.
>

Such a race is prevented with kvm_hstate.hwthread_req and
kvm_hstate.hwthread_state paca flags.

The current flow when a guest is scheduled on a core :
-> Primary thread sets kvm_hstate.hwthread_req paca flag for all the
secondary threads.
-> Waits for all the secondary threads to to change state to
!KVM_HWTHREAD_IN_KERNEL
-> and later call __kvmppc_vcore_entry which down the line changes SDR1
and other per core registers. Therefore kvm_hstate.hwthread_req is set
to 1 for all the threads in the core *before* SDR1 is switched.

And when a secondary thread is woken up to execute guest, in 0x100 we
check hwthread_req and branch to kvm_start_guest if set. Therefore
secondary threads woken up for guest do not execute the
power7_wakeup_hv_state_loss and therefore there is no danger of
overwriting SDR1 or TBU40.

Now lets consider the case where a guest is scheduled on the core and a
secondary thread is woken up even though there is no vcpu to run on it.
(Say its woken up by a stray IPI). In this case, again in 0x100 we
branch to kvm_start_guest, and here when there is no vcpu to run, it
executes nap. So again there no danger of overwriting SDR1.

>> +	/* Restore SLB  from PACA */
>> +	ld	r8,PACA_SLBSHADOWPTR(r13)
>> +
>> +	.rept	SLB_NUM_BOLTED
>> +	li	r3, SLBSHADOW_SAVEAREA
>> +	LDX_BE	r5, r8, r3
>> +	addi	r3, r3, 8
>> +	LDX_BE	r6, r8, r3
>> +	andis.	r7,r5,SLB_ESID_V@h
>> +	beq	1f
>> +	slbmte	r6,r5
>> +1:	addi	r8,r8,16
>> +	.endr
>> +
>> +	ld      r4,_SDR1(r1)
>> +	mtspr   SPRN_SDR1,r4
>> +
>> +	ld      r4,_TSCR(r1)
>> +	mtspr   SPRN_TSCR,r4
>> +
>> +	REST_NVGPRS(r1)
>> +	REST_GPR(2, r1)
>> +	ld      r3,_CCR(r1)
>> +	ld      r4,_MSR(r1)
>> +	ld      r5,_NIP(r1)
>> +	addi    r1,r1,INT_FRAME_SIZE
>> +	mtcr    r3
>> +	mfspr   r3,SPRN_SRR1            /* Return SRR1 */
>> +	mtspr   SPRN_SRR1,r4
>> +	mtspr   SPRN_SRR0,r5
>> +	rfid
>> +
>>  _GLOBAL(power7_wakeup_tb_loss)
>>  	ld	r2,PACATOC(r13);
>>  	ld	r1,PACAR1(r13)
>> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
>> index 9d9a898..f45b52d 100644
>> --- a/arch/powerpc/platforms/powernv/setup.c
>> +++ b/arch/powerpc/platforms/powernv/setup.c
>> @@ -370,6 +370,29 @@ static unsigned long pnv_power7_sleep(void)
>>  	return srr1;
>>  }
>>  
>> +/*
>> + * We need to keep track of offline cpus also for calling
>> + * fastsleep workaround appropriately
>> + */
>> +static unsigned long pnv_power7_winkle(void)
>> +{
>> +	int cpu, primary_thread;
>> +	unsigned long srr1;
>> +
>> +	cpu = smp_processor_id();
>> +	primary_thread = cpu_first_thread_sibling(cpu);
>> +
>> +	if (need_fastsleep_workaround) {
>> +		pnv_apply_fastsleep_workaround(1, primary_thread);
>> +		srr1 = __power7_winkle();
>> +		pnv_apply_fastsleep_workaround(0, primary_thread);
>> +	} else {
>> +			srr1 = __power7_winkle();
>> +	}
>> +	return srr1;
>> +}
>> +
>> +
>>  static void __init pnv_setup_machdep_opal(void)
>>  {
>>  	ppc_md.get_boot_time = opal_get_boot_time;
>> @@ -384,6 +407,7 @@ static void __init pnv_setup_machdep_opal(void)
>>  	ppc_md.handle_hmi_exception = opal_handle_hmi_exception;
>>  	ppc_md.setup_idle = pnv_setup_idle;
>>  	ppc_md.power7_sleep = pnv_power7_sleep;
>> +	ppc_md.power7_winkle = pnv_power7_winkle;
>>  }
>>  
>>  #ifdef CONFIG_PPC_POWERNV_RTAS
> 
>