thermal: intel: Protect clearing of thermal status bits

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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c
index 239afe02e518..65b902939e1f 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);