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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: 1e1601b38e ("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>
This commit is contained in:
Gautham R. Shenoy 2017-08-08 14:13:15 +05:30 committed by Michael Ellerman
parent 44a12806d0
commit 785a12afdb
2 changed files with 48 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
arch/powerpc/platforms/powernv/idle.c
View File

@ -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;
}

10
drivers/cpuidle/cpuidle-powernv.c
View File

@ -235,6 +235,7 @@ static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
return -1;
}
extern u32 pnv_get_supported_cpuidle_states(void);
static int powernv_add_idle_states(void)
{
struct device_node *power_mgt;
@ -248,6 +249,8 @@ static int powernv_add_idle_states(void)
const char *names[CPUIDLE_STATE_MAX];
u32 has_stop_states = 0;
int i, rc;
u32 supported_flags = pnv_get_supported_cpuidle_states();
/* Currently we have snooze statically defined */
@ -362,6 +365,13 @@ static int powernv_add_idle_states(void)
for (i = 0; i < dt_idle_states; i++) {
unsigned int exit_latency, target_residency;
bool stops_timebase = false;
/*
* Skip the platform idle state whose flag isn't in
* the supported_cpuidle_states flag mask.
*/
if ((flags[i] & supported_flags) != flags[i])
continue;
/*
* If an idle state has exit latency beyond
* POWERNV_THRESHOLD_LATENCY_NS then don't use it