[RFC v2 1/2] powerpc/powernv : Add support for pre-entry and post-exit of stop state using OPAL V4 OS services

[RFC v2 1/2] powerpc/powernv : Add support for pre-entry and post-exit of stop state using OPAL V4 OS services

[Abhishek Goel]

This patch provides kernel framework fro opal support of save restore
of sprs in idle stop loop. Opal support for stop states is needed to
selectively enable stop states or to introduce a quirk quickly in case
a buggy stop state is present.

We make a opal call from kernel if firmware-stop-support for stop
states is present and enabled. All the quirks for pre-entry of stop
state is handled inside opal. A call from opal is made into kernel
where we execute stop afer saving of NVGPRs.
After waking up from 0x100 vector in kernel, we enter back into opal.
All the quirks in post exit path, if any, are then handled in opal,
from where we return successfully back to kernel.

Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com>
---
v1->v2 : Rebased the patch on Nick's Opal V4 OS patchset

 arch/powerpc/include/asm/opal-api.h        |  4 +++-
 arch/powerpc/include/asm/opal.h            |  1 +
 arch/powerpc/platforms/powernv/idle.c      | 12 ++++++++++++
 arch/powerpc/platforms/powernv/opal-call.c |  1 +
 arch/powerpc/platforms/powernv/opal.c      | 15 +++++++++++++++
 5 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
index 97c5e5423827..437b6937685d 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -219,7 +219,8 @@
 #define OPAL_REPORT_TRAP			183
 #define OPAL_FIND_VM_AREA			184
 #define OPAL_REGISTER_OS_OPS			185
-#define OPAL_LAST				185
+#define OPAL_CPU_IDLE				186
+#define OPAL_LAST				186
 
 #define QUIESCE_HOLD			1 /* Spin all calls at entry */
 #define QUIESCE_REJECT			2 /* Fail all calls with OPAL_BUSY */
@@ -1207,6 +1208,7 @@ struct opal_os_ops {
 	__be64  os_printf; /* void printf(int32_t level, const char *str) */
 	__be64  os_vm_map; /* int64_t os_vm_map(uint64_t ea, uint64_t pa, uint64_t flags) */
 	__be64  os_vm_unmap; /* void os_vm_unmap(uint64_t ea) */
+	__be64  os_idle_stop; /* void os_idle_stop(uint64_t srr1_addr, uint64_t psscr) */
 };
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 09985b7718b3..1774c056acb8 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -407,6 +407,7 @@ void opal_sensor_groups_init(void);
 
 int64_t opal_find_vm_area(uint64_t addr, struct opal_vm_area *opal_vm_area);
 int64_t opal_register_os_ops(struct opal_os_ops *ops, uint64_t size);
+int64_t opal_cpu_idle(uint64_t srr1_addr, uint64_t psscr);
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 78599bca66c2..3afd4293f729 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -805,6 +805,18 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
 	return srr1;
 }
 
+static unsigned long power9_firmware_idle_stop(unsigned long psscr, bool mmu_on)
+{
+	unsigned long srr1;
+	int rc;
+
+	rc = opal_cpu_idle(cpu_to_be64(&srr1), (uint64_t) psscr);
+
+	if (mmu_on)
+		mtmsr(MSR_KERNEL);
+	return srr1;
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 static unsigned long power9_offline_stop(unsigned long psscr)
 {
diff --git a/arch/powerpc/platforms/powernv/opal-call.c b/arch/powerpc/platforms/powernv/opal-call.c
index 11f419e76059..79076ca2de03 100644
--- a/arch/powerpc/platforms/powernv/opal-call.c
+++ b/arch/powerpc/platforms/powernv/opal-call.c
@@ -351,3 +351,4 @@ OPAL_CALL(opal_sym_to_addr,			OPAL_SYM_TO_ADDR);
 OPAL_CALL(opal_report_trap,			OPAL_REPORT_TRAP);
 OPAL_CALL(opal_find_vm_area,			OPAL_FIND_VM_AREA);
 OPAL_CALL(opal_register_os_ops,			OPAL_REGISTER_OS_OPS);
+OPAL_CALL(opal_cpu_idle,			OPAL_CPU_IDLE);
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 93b9afaf33b3..1fbf7065f918 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -1150,6 +1150,20 @@ static void os_vm_unmap(uint64_t ea)
 	local_flush_tlb_mm(mm);
 }
 
+int64_t os_idle_stop(uint64_t srr1_addr, uint64_t psscr)
+{
+	/*
+	 * For lite state which does not lose even GPRS we call
+	 * idle_stop_noloss while for all other states we call
+	 * idle_stop_mayloss. Saving and restoration of other additional
+	 * SPRs if required is handled in OPAL. All the quirks are also
+	 * handled in OPAL.
+	 */
+	if (!(psscr & (PSSCR_EC|PSSCR_ESL)))
+		return isa300_idle_stop_noloss(psscr);
+	return isa300_idle_stop_mayloss(psscr);
+}
+
 static int __init opal_init_mm(void)
 {
 	struct mm_struct *mm;
@@ -1231,6 +1245,7 @@ static int __init opal_init_early(void)
 		opal_os_ops.os_printf = cpu_to_be64(&os_printf);
 		opal_os_ops.os_vm_map = cpu_to_be64(&os_vm_map);
 		opal_os_ops.os_vm_unmap = cpu_to_be64(&os_vm_unmap);
+		opal_os_ops.os_idle_stop = cpu_to_be64(&os_idle_stop);
 		if (opal_register_os_ops(&opal_os_ops, sizeof(opal_os_ops))) {
 			pr_warn("OPAL register OS ops failed, firmware will run in v3 mode.\n");
 		} else {
-- 
2.17.1

[RFC v2 2/2] powerpc/powernv : Introduce capability for firmware-enabled-stop

[Abhishek Goel]

This patch introduces the capability for firmware to handle the stop
states instead. A bit is set based on the discovery of the feature
and correspondingly also the responsibility to handle the stop states.

If Kernel does not know about stop version, it can fallback to opal for
idle stop support if firmware-stop-supported property is present.

Earlier part of this patch was posted in this series :
https://lkml.org/lkml/2020/3/4/589

Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com>
Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
---
v1->v2 : Combined patch 2 and 3 from previous iteration and rebased it.

 arch/powerpc/include/asm/processor.h  | 18 ++++++++++++++++++
 arch/powerpc/kernel/dt_cpu_ftrs.c     | 13 +++++++++++++
 arch/powerpc/platforms/powernv/idle.c | 20 ++++++++++++++++----
 drivers/cpuidle/cpuidle-powernv.c     |  3 ++-
 4 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index bfa336fbcfeb..b8de7146387c 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -428,6 +428,24 @@ extern void power4_idle_nap(void);
 extern unsigned long cpuidle_disable;
 enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 
+#define STOP_ENABLE		0x00000001
+#define FIRMWARE_STOP_ENABLE	0x00000010
+
+#define STOP_VERSION_P9       0x1
+
+/*
+ * Classify the dependencies of the stop states
+ * @idle_stop: function handler to handle the quirk stop version
+ * @cpuidle_prop: Signify support for stop states through kernel and/or firmware
+ * @stop_version: Classify quirk versions for stop states
+ */
+typedef struct {
+	unsigned long (*idle_stop)(unsigned long psscr, bool mmu_on);
+	uint8_t cpuidle_prop;
+	uint8_t stop_version;
+} stop_deps_t;
+extern stop_deps_t stop_dep;
+
 extern int powersave_nap;	/* set if nap mode can be used in idle loop */
 
 extern void power7_idle_type(unsigned long type);
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 36bc0d5c4f3a..737686fae3c7 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -291,6 +291,15 @@ static int __init feat_enable_idle_stop(struct dt_cpu_feature *f)
 	lpcr |=  LPCR_PECE1;
 	lpcr |=  LPCR_PECE2;
 	mtspr(SPRN_LPCR, lpcr);
+	stop_dep.cpuidle_prop |= STOP_ENABLE;
+	stop_dep.stop_version = STOP_VERSION_P9;
+
+	return 1;
+}
+
+static int __init feat_enable_firmware_stop(struct dt_cpu_feature *f)
+{
+	stop_dep.cpuidle_prop |= FIRMWARE_STOP_ENABLE;
 
 	return 1;
 }
@@ -589,6 +598,7 @@ static struct dt_cpu_feature_match __initdata
 	{"idle-nap", feat_enable_idle_nap, 0},
 	{"alignment-interrupt-dsisr", feat_enable_align_dsisr, 0},
 	{"idle-stop", feat_enable_idle_stop, 0},
+	{"firmware-stop-supported", feat_enable_firmware_stop, 0},
 	{"machine-check-power8", feat_enable_mce_power8, 0},
 	{"performance-monitor-power8", feat_enable_pmu_power8, 0},
 	{"data-stream-control-register", feat_enable_dscr, CPU_FTR_DSCR},
@@ -656,6 +666,9 @@ static void __init cpufeatures_setup_start(u32 isa)
 	}
 }
 
+stop_deps_t stop_dep = {NULL, 0x0, 0x0};
+EXPORT_SYMBOL(stop_dep);
+
 static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
 {
 	const struct dt_cpu_feature_match *m;
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 3afd4293f729..3602950f6c08 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -824,7 +824,7 @@ static unsigned long power9_offline_stop(unsigned long psscr)
 
 #ifndef CONFIG_KVM_BOOK3S_HV_POSSIBLE
 	__ppc64_runlatch_off();
-	srr1 = power9_idle_stop(psscr, true);
+	srr1 = stop_dep.idle_stop(psscr, true);
 	__ppc64_runlatch_on();
 #else
 	/*
@@ -840,7 +840,7 @@ static unsigned long power9_offline_stop(unsigned long psscr)
 	local_paca->kvm_hstate.hwthread_state = KVM_HWTHREAD_IN_IDLE;
 
 	__ppc64_runlatch_off();
-	srr1 = power9_idle_stop(psscr, false);
+	srr1 = stop_dep.idle_stop(psscr, true);
 	__ppc64_runlatch_on();
 
 	local_paca->kvm_hstate.hwthread_state = KVM_HWTHREAD_IN_KERNEL;
@@ -868,7 +868,7 @@ void power9_idle_type(unsigned long stop_psscr_val,
 	psscr = (psscr & ~stop_psscr_mask) | stop_psscr_val;
 
 	__ppc64_runlatch_off();
-	srr1 = power9_idle_stop(psscr, true);
+	srr1 = stop_dep.idle_stop(psscr, true);
 	__ppc64_runlatch_on();
 
 	fini_irq_for_idle_irqsoff();
@@ -1365,8 +1365,20 @@ static int __init pnv_init_idle_states(void)
 	nr_pnv_idle_states = 0;
 	supported_cpuidle_states = 0;
 
-	if (cpuidle_disable != IDLE_NO_OVERRIDE)
+	if (cpuidle_disable != IDLE_NO_OVERRIDE ||
+	    !(stop_dep.cpuidle_prop & STOP_ENABLE))
 		goto out;
+
+	/* Check for supported version in kernel or fallback to opal*/
+	if (stop_dep.stop_version & STOP_VERSION_P9) {
+		stop_dep.idle_stop = power9_idle_stop;
+	} else if (stop_dep.cpuidle_prop & FIRMWARE_STOP_ENABLE) {
+		stop_dep.idle_stop = power9_firmware_idle_stop;
+	} else {
+		stop_dep.idle_stop = NULL;
+		goto out;
+	}
+
 	rc = pnv_parse_cpuidle_dt();
 	if (rc)
 		return rc;
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 1b299e801f74..7430a8edf5c9 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -371,7 +371,8 @@ static int powernv_add_idle_states(void)
  */
 static int powernv_idle_probe(void)
 {
-	if (cpuidle_disable != IDLE_NO_OVERRIDE)
+	if (cpuidle_disable != IDLE_NO_OVERRIDE ||
+	    !(stop_dep.cpuidle_prop & STOP_ENABLE))
 		return -ENODEV;
 
 	if (firmware_has_feature(FW_FEATURE_OPAL)) {
-- 
2.17.1