Bay Trail (BYT) and Cherry Trail (CHT) platforms have a very specific way
of disabling auto-demotion via specific MSR bits. Clean up the code so that
BYT/CHT-specifics do not show up in the common 'struct idle_cpu' data
structure.
Remove the 'byt_auto_demotion_disable_flag' flag from 'struct idle_cpu',
because a better coding pattern is to avoid very case-specific fields like
'bool byt_auto_demotion_disable_flag' in a common data structure, which is
used for all platforms, not only BYT/CHT. The code is just more readable
when common data structures contain only commonly used fields.
Instead, match BYT/CHT in the 'intel_idle_init_cstates_icpu()' function,
and introduce a small helper to take care of BYT/CHT auto-demotion. This
is consistent with how platform-specific things are done for other
platforms.
No intended functional changes.
Inspired by (and description largely taken from) Linux'es c93d13b661a6
("intel_idle: clean up BYT/CHT auto demotion disable").
Signed-off-by: Jan Beulich <[email protected]>
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -104,7 +104,6 @@ struct idle_cpu {
* Indicate which enable bits to clear here.
*/
unsigned long auto_demotion_disable_flags;
- bool byt_auto_demotion_disable_flag;
enum c1e_promotion c1e_promotion;
};
@@ -1144,7 +1143,7 @@ static void cf_check auto_demotion_disab
wrmsrl(MSR_PKG_CST_CONFIG_CONTROL, msr_bits);
}
-static void cf_check byt_auto_demotion_disable(void *dummy)
+static void byt_cht_auto_demotion_disable(void)
{
wrmsrl(MSR_CC6_DEMOTION_POLICY_CONFIG, 0);
wrmsrl(MSR_MC6_DEMOTION_POLICY_CONFIG, 0);
@@ -1195,13 +1194,11 @@ static const struct idle_cpu idle_cpu_sn
static const struct idle_cpu idle_cpu_byt = {
.state_table = byt_cstates,
.c1e_promotion = C1E_PROMOTION_DISABLE,
- .byt_auto_demotion_disable_flag = true,
};
static const struct idle_cpu idle_cpu_cht = {
.state_table = cht_cstates,
.c1e_promotion = C1E_PROMOTION_DISABLE,
- .byt_auto_demotion_disable_flag = true,
};
static const struct idle_cpu idle_cpu_ivb = {
@@ -1680,14 +1677,11 @@ static int __init mwait_idle_probe(void)
return 0;
}
-static void mwait_idle_cpu_tweak(unsigned int cpu)
+static void mwait_idle_cpu_tweak(unsigned int cpu, bool bsp)
{
if (icpu->auto_demotion_disable_flags)
on_selected_cpus(cpumask_of(cpu), auto_demotion_disable, NULL,
1);
- if (icpu->byt_auto_demotion_disable_flag)
- on_selected_cpus(cpumask_of(cpu), byt_auto_demotion_disable,
NULL, 1);
-
switch (icpu->c1e_promotion) {
case C1E_PROMOTION_DISABLE:
on_selected_cpus(cpumask_of(cpu), c1e_promotion_disable, NULL,
1);
@@ -1700,12 +1694,24 @@ static void mwait_idle_cpu_tweak(unsigne
case C1E_PROMOTION_PRESERVE:
break;
}
+
+ /* Pkg-scope MSRs on 1-socket-only systems need writing only once. */
+ if (!bsp)
+ return;
+
+ switch (boot_cpu_data.vfm) {
+ case INTEL_ATOM_SILVERMONT:
+ case INTEL_ATOM_AIRMONT:
+ byt_cht_auto_demotion_disable();
+ break;
+ }
}
static int cf_check mwait_idle_cpu_init(
struct notifier_block *nfb, unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu, cstate;
+ static bool first;
struct acpi_processor_power *dev = processor_powers[cpu];
switch (action) {
@@ -1784,7 +1790,8 @@ static int cf_check mwait_idle_cpu_init(
dev->count++;
}
- mwait_idle_cpu_tweak(cpu);
+ mwait_idle_cpu_tweak(cpu, first);
+ first = false;
return NOTIFY_DONE;
}
@@ -1821,7 +1828,7 @@ void mwait_idle_resume(void)
if (!icpu)
return;
- mwait_idle_cpu_tweak(smp_processor_id());
+ mwait_idle_cpu_tweak(smp_processor_id(), true);
}
/* Helper function for HPET. */
