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authorGautham R. Shenoy <ego@linux.vnet.ibm.com>2017-08-08 14:13:15 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2017-08-08 20:21:23 +1000
commit785a12afdb4a52903447fd890633c82fdda4b6f7 (patch)
treed91beb5aff31b950f8a2620306e70117c173976f /arch/powerpc
parent44a12806d010944a5727f1dc99123121e3e2c8c6 (diff)
powerpc/powernv/idle: Disable LOSE_FULL_CONTEXT states when stop-api fails
Currently, we use the opal call opal_slw_set_reg() to inform the Sleep-Winkle Engine (SLW) to restore the contents of some of the Hypervisor state on wakeup from deep idle states that lose full hypervisor context (characterized by the flag OPAL_PM_LOSE_FULL_CONTEXT). However, the current code has a bug in that if opal_slw_set_reg() fails, we don't disable the use of these deep states (winkle on POWER8, stop4 onwards on POWER9). This patch fixes this bug by ensuring that if programing the sleep-winkle engine to restore the hypervisor states in pnv_save_sprs_for_deep_states() fails, then we exclude such states by clearing the OPAL_PM_LOSE_FULL_CONTEXT flag from supported_cpuidle_states. As a result POWER8 will be prevented from using winkle for CPU-Hotplug, and POWER9 will put the offlined CPUs to the default stop state when available. Further, we ensure in the initialization of the cpuidle-powernv driver to only include those states whose flags are present in supported_cpuidle_states, thereby skipping OPAL_PM_LOSE_FULL_CONTEXT states when they have been disabled due to stop-api failure. Fixes: 1e1601b38e6 ("powerpc/powernv/idle: Restore SPRs for deep idle states via stop API.") Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/platforms/powernv/idle.c41
1 files changed, 38 insertions, 3 deletions
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 2abee070373f..a553aeea7af6 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -56,6 +56,7 @@ u64 pnv_first_deep_stop_state = MAX_STOP_STATE;
*/
static u64 pnv_deepest_stop_psscr_val;
static u64 pnv_deepest_stop_psscr_mask;
+static u64 pnv_deepest_stop_flag;
static bool deepest_stop_found;
static int pnv_save_sprs_for_deep_states(void)
@@ -185,8 +186,40 @@ static void pnv_alloc_idle_core_states(void)
update_subcore_sibling_mask();
- if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT)
- pnv_save_sprs_for_deep_states();
+ if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT) {
+ int rc = pnv_save_sprs_for_deep_states();
+
+ if (likely(!rc))
+ return;
+
+ /*
+ * The stop-api is unable to restore hypervisor
+ * resources on wakeup from platform idle states which
+ * lose full context. So disable such states.
+ */
+ supported_cpuidle_states &= ~OPAL_PM_LOSE_FULL_CONTEXT;
+ pr_warn("cpuidle-powernv: Disabling idle states that lose full context\n");
+ pr_warn("cpuidle-powernv: Idle power-savings, CPU-Hotplug affected\n");
+
+ if (cpu_has_feature(CPU_FTR_ARCH_300) &&
+ (pnv_deepest_stop_flag & OPAL_PM_LOSE_FULL_CONTEXT)) {
+ /*
+ * Use the default stop state for CPU-Hotplug
+ * if available.
+ */
+ if (default_stop_found) {
+ pnv_deepest_stop_psscr_val =
+ pnv_default_stop_val;
+ pnv_deepest_stop_psscr_mask =
+ pnv_default_stop_mask;
+ pr_warn("cpuidle-powernv: Offlined CPUs will stop with psscr = 0x%016llx\n",
+ pnv_deepest_stop_psscr_val);
+ } else { /* Fallback to snooze loop for CPU-Hotplug */
+ deepest_stop_found = false;
+ pr_warn("cpuidle-powernv: Offlined CPUs will busy wait\n");
+ }
+ }
+ }
}
u32 pnv_get_supported_cpuidle_states(void)
@@ -375,7 +408,8 @@ unsigned long pnv_cpu_offline(unsigned int cpu)
pnv_deepest_stop_psscr_val;
srr1 = power9_idle_stop(psscr);
- } else if (idle_states & OPAL_PM_WINKLE_ENABLED) {
+ } else if ((idle_states & OPAL_PM_WINKLE_ENABLED) &&
+ (idle_states & OPAL_PM_LOSE_FULL_CONTEXT)) {
srr1 = power7_idle_insn(PNV_THREAD_WINKLE);
} else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
(idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
@@ -553,6 +587,7 @@ static int __init pnv_power9_idle_init(struct device_node *np, u32 *flags,
max_residency_ns = residency_ns[i];
pnv_deepest_stop_psscr_val = psscr_val[i];
pnv_deepest_stop_psscr_mask = psscr_mask[i];
+ pnv_deepest_stop_flag = flags[i];
deepest_stop_found = true;
}