Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Fri, 18 Nov 2022 18:57:24 +0100 | Subject | Re: [PATCH RESEND 2/2] thermal: intel: Protect clearing of thermal status bits |
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On Wed, Nov 16, 2022 at 3:54 AM Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote: > > The clearing of the package thermal status is done by Read-Modify-Write > operation. This may result in clearing of some new status bits which are > being or about to be processed. > > For example, while clearing of HFI status, after read of thermal status > register, a new thermal status bit is set by the hardware. But during > write back, the newly generated status bit will be set to 0 or cleared. > So, it is not safe to do read-modify-write. > > Since thermal status Read-Write bits can be set to only 0 not 1, it is > safe to set all other bits to 1 which are not getting cleared. > > Create a common interface for clearing package thermal status bits. Use > this interface to replace existing code to clear thermal package status > bits. > > It is safe to call from different CPUs without protection as there is no > read-modify-write. Also wrmsrl results in just single instruction. For > example while CPU 0 and CPU 3 are clearing bit 1 and 3 respectively. If > CPU 3 wins the race, it will write 0x4000aa2, then CPU 1 will write > 0x4000aa8. The bits which are not part of clear are set to 1. The default > mask for bits, which can be written here is 0x4000aaa. > > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> > Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
How urgent is this? Would 6.2 be sufficient?
Also, do you want it to go into -stable?
> --- > Email address was wrong, so sending again. > > drivers/thermal/intel/intel_hfi.c | 8 ++----- > drivers/thermal/intel/therm_throt.c | 23 ++++++++++---------- > drivers/thermal/intel/thermal_interrupt.h | 6 +++++ > drivers/thermal/intel/x86_pkg_temp_thermal.c | 9 ++------ > 4 files changed, 22 insertions(+), 24 deletions(-) > > diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c > index a0640f762dc5..c9e0827c9ebe 100644 > --- a/drivers/thermal/intel/intel_hfi.c > +++ b/drivers/thermal/intel/intel_hfi.c > @@ -42,9 +42,7 @@ > > #include "../thermal_core.h" > #include "intel_hfi.h" > - > -#define THERM_STATUS_CLEAR_PKG_MASK (BIT(1) | BIT(3) | BIT(5) | BIT(7) | \ > - BIT(9) | BIT(11) | BIT(26)) > +#include "thermal_interrupt.h" > > /* Hardware Feedback Interface MSR configuration bits */ > #define HW_FEEDBACK_PTR_VALID_BIT BIT(0) > @@ -304,9 +302,7 @@ void intel_hfi_process_event(__u64 pkg_therm_status_msr_val) > * Let hardware know that we are done reading the HFI table and it is > * free to update it again. > */ > - pkg_therm_status_msr_val &= THERM_STATUS_CLEAR_PKG_MASK & > - ~PACKAGE_THERM_STATUS_HFI_UPDATED; > - wrmsrl(MSR_IA32_PACKAGE_THERM_STATUS, pkg_therm_status_msr_val); > + thermal_clear_package_intr_status(PACKAGE_LEVEL, PACKAGE_THERM_STATUS_HFI_UPDATED); > > queue_delayed_work(hfi_updates_wq, &hfi_instance->update_work, > HFI_UPDATE_INTERVAL); > diff --git a/drivers/thermal/intel/therm_throt.c b/drivers/thermal/intel/therm_throt.c > index 9e8ab31d756e..4bb7fddaa143 100644 > --- a/drivers/thermal/intel/therm_throt.c > +++ b/drivers/thermal/intel/therm_throt.c > @@ -190,32 +190,33 @@ static const struct attribute_group thermal_attr_group = { > }; > #endif /* CONFIG_SYSFS */ > > -#define CORE_LEVEL 0 > -#define PACKAGE_LEVEL 1 > - > #define THERM_THROT_POLL_INTERVAL HZ > #define THERM_STATUS_PROCHOT_LOG BIT(1) > > #define THERM_STATUS_CLEAR_CORE_MASK (BIT(1) | BIT(3) | BIT(5) | BIT(7) | BIT(9) | BIT(11) | BIT(13) | BIT(15)) > #define THERM_STATUS_CLEAR_PKG_MASK (BIT(1) | BIT(3) | BIT(5) | BIT(7) | BIT(9) | BIT(11) | BIT(26)) > > -static void clear_therm_status_log(int level) > +/* > + * Clear the bits in package thermal status register for bit = 1 > + * in bitmask > + */ > +void thermal_clear_package_intr_status(int level, u64 bit_mask) > { > + u64 msr_val; > int msr; > - u64 mask, msr_val; > > if (level == CORE_LEVEL) { > msr = MSR_IA32_THERM_STATUS; > - mask = THERM_STATUS_CLEAR_CORE_MASK; > + msr_val = THERM_STATUS_CLEAR_CORE_MASK; > } else { > msr = MSR_IA32_PACKAGE_THERM_STATUS; > - mask = THERM_STATUS_CLEAR_PKG_MASK; > + msr_val = THERM_STATUS_CLEAR_PKG_MASK; > } > > - rdmsrl(msr, msr_val); > - msr_val &= mask; > - wrmsrl(msr, msr_val & ~THERM_STATUS_PROCHOT_LOG); > + msr_val &= ~bit_mask; > + wrmsrl(msr, msr_val); > } > +EXPORT_SYMBOL_GPL(thermal_clear_package_intr_status); > > static void get_therm_status(int level, bool *proc_hot, u8 *temp) > { > @@ -295,7 +296,7 @@ static void __maybe_unused throttle_active_work(struct work_struct *work) > state->average = avg; > > re_arm: > - clear_therm_status_log(state->level); > + thermal_clear_package_intr_status(state->level, THERM_STATUS_PROCHOT_LOG); > schedule_delayed_work_on(this_cpu, &state->therm_work, THERM_THROT_POLL_INTERVAL); > } > > diff --git a/drivers/thermal/intel/thermal_interrupt.h b/drivers/thermal/intel/thermal_interrupt.h > index 01e7bed2ffc7..01dfd4cdb5df 100644 > --- a/drivers/thermal/intel/thermal_interrupt.h > +++ b/drivers/thermal/intel/thermal_interrupt.h > @@ -2,6 +2,9 @@ > #ifndef _INTEL_THERMAL_INTERRUPT_H > #define _INTEL_THERMAL_INTERRUPT_H > > +#define CORE_LEVEL 0 > +#define PACKAGE_LEVEL 1 > + > /* Interrupt Handler for package thermal thresholds */ > extern int (*platform_thermal_package_notify)(__u64 msr_val); > > @@ -15,4 +18,7 @@ extern bool (*platform_thermal_package_rate_control)(void); > /* Handle HWP interrupt */ > extern void notify_hwp_interrupt(void); > > +/* Common function to clear Package thermal status register */ > +extern void thermal_clear_package_intr_status(int level, u64 bit_mask); > + > #endif /* _INTEL_THERMAL_INTERRUPT_H */ > diff --git a/drivers/thermal/intel/x86_pkg_temp_thermal.c b/drivers/thermal/intel/x86_pkg_temp_thermal.c > index a0e234fce71a..84c3a116ed04 100644 > --- a/drivers/thermal/intel/x86_pkg_temp_thermal.c > +++ b/drivers/thermal/intel/x86_pkg_temp_thermal.c > @@ -265,7 +265,6 @@ static void pkg_temp_thermal_threshold_work_fn(struct work_struct *work) > struct thermal_zone_device *tzone = NULL; > int cpu = smp_processor_id(); > struct zone_device *zonedev; > - u64 msr_val, wr_val; > > mutex_lock(&thermal_zone_mutex); > raw_spin_lock_irq(&pkg_temp_lock); > @@ -279,12 +278,8 @@ static void pkg_temp_thermal_threshold_work_fn(struct work_struct *work) > } > zonedev->work_scheduled = false; > > - rdmsrl(MSR_IA32_PACKAGE_THERM_STATUS, msr_val); > - wr_val = msr_val & ~(THERM_LOG_THRESHOLD0 | THERM_LOG_THRESHOLD1); > - if (wr_val != msr_val) { > - wrmsrl(MSR_IA32_PACKAGE_THERM_STATUS, wr_val); > - tzone = zonedev->tzone; > - } > + thermal_clear_package_intr_status(PACKAGE_LEVEL, THERM_LOG_THRESHOLD0 | THERM_LOG_THRESHOLD1); > + tzone = zonedev->tzone; > > enable_pkg_thres_interrupt(); > raw_spin_unlock_irq(&pkg_temp_lock); > -- > 2.31.1 >
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