6.1-stable review patch. If anyone has any objections, please let me know.
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From: Rafael J. Wysocki rafael.j.wysocki@intel.com
[ Upstream commit 350cbb5d2f676bff22c49e5e81764c3b8da342a9 ]
After recent changes in intel_pstate, global.turbo_disabled is only set at the initialization time and never changed. However, it turns out that on some systems the "turbo disabled" bit in MSR_IA32_MISC_ENABLE, the initial state of which is reflected by global.turbo_disabled, can be flipped later and there should be a way to take that into account (other than checking that MSR every time the driver runs which is costly and useless overhead on the vast majority of systems).
For this purpose, notice that before the changes in question, store_no_turbo() contained a turbo_is_disabled() check that was used for updating global.turbo_disabled if the "turbo disabled" bit in MSR_IA32_MISC_ENABLE had been flipped and that functionality can be restored. Then, users will be able to reset global.turbo_disabled by writing 0 to no_turbo which used to work before on systems with flipping "turbo disabled" bit.
This guarantees the driver state to remain in sync, but READ_ONCE() annotations need to be added in two places where global.turbo_disabled is accessed locklessly, so modify the driver to make that happen.
Fixes: 0940f1a8011f ("cpufreq: intel_pstate: Do not update global.turbo_disabled after initialization") Closes: https://lore.kernel.org/linux-pm/bf3ebf1571a4788e97daf861eb493c12d42639a3.ca... Suggested-by: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com Reported-by: Xi Ruoyao xry111@xry111.site Tested-by: Xi Ruoyao xry111@xry111.site Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpufreq/intel_pstate.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 7570d6d1ca8c0..3ded51db833d7 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -1255,12 +1255,17 @@ static ssize_t store_no_turbo(struct kobject *a, struct kobj_attribute *b,
no_turbo = !!clamp_t(int, input, 0, 1);
- if (no_turbo == global.no_turbo) - goto unlock_driver; - - if (global.turbo_disabled) { - pr_notice_once("Turbo disabled by BIOS or unavailable on processor\n"); + WRITE_ONCE(global.turbo_disabled, turbo_is_disabled()); + if (global.turbo_disabled && !no_turbo) { + pr_notice("Turbo disabled by BIOS or unavailable on processor\n"); count = -EPERM; + if (global.no_turbo) + goto unlock_driver; + else + no_turbo = 1; + } + + if (no_turbo == global.no_turbo) { goto unlock_driver; }
@@ -1730,7 +1735,7 @@ static u64 atom_get_val(struct cpudata *cpudata, int pstate) u32 vid;
val = (u64)pstate << 8; - if (READ_ONCE(global.no_turbo) && !global.turbo_disabled) + if (READ_ONCE(global.no_turbo) && !READ_ONCE(global.turbo_disabled)) val |= (u64)1 << 32;
vid_fp = cpudata->vid.min + mul_fp( @@ -1900,7 +1905,7 @@ static u64 core_get_val(struct cpudata *cpudata, int pstate) u64 val;
val = (u64)pstate << 8; - if (READ_ONCE(global.no_turbo) && !global.turbo_disabled) + if (READ_ONCE(global.no_turbo) && !READ_ONCE(global.turbo_disabled)) val |= (u64)1 << 32;
return val;