x86/mce: Make timer handling more robust

Erik reported that on a preproduction hardware a CMCI storm triggers the
BUG_ON in add_timer_on(). The reason is that the per CPU MCE timer is
started by the CMCI logic before the MCE CPU hotplug callback starts the
timer with add_timer_on(). So the timer is already queued which triggers
the BUG.

Using add_timer_on() is pretty pointless in this code because the timer is
strictlty per CPU, initialized as pinned and all operations which arm the
timer happen on the CPU to which the timer belongs.

Simplify the whole machinery by using mod_timer() instead of add_timer_on()
which avoids the problem because mod_timer() can handle already queued
timers. Use __start_timer() everywhere so the earliest armed expiry time is
preserved.

Reported-by: Erik Veijola <erik.veijola@intel.com>
Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701310936080.3457@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

path: root/include/acpi/pdc_intel.h

/* _PDC bit definition for Intel processors */

#ifndef __PDC_INTEL_H__
#define __PDC_INTEL_H__

#define ACPI_PDC_P_FFH			(0x0001)
#define ACPI_PDC_C_C1_HALT		(0x0002)
#define ACPI_PDC_T_FFH			(0x0004)
#define ACPI_PDC_SMP_C1PT		(0x0008)
#define ACPI_PDC_SMP_C2C3		(0x0010)
#define ACPI_PDC_SMP_P_SWCOORD		(0x0020)
#define ACPI_PDC_SMP_C_SWCOORD		(0x0040)
#define ACPI_PDC_SMP_T_SWCOORD		(0x0080)
#define ACPI_PDC_C_C1_FFH		(0x0100)
#define ACPI_PDC_C_C2C3_FFH		(0x0200)
#define ACPI_PDC_SMP_P_HWCOORD		(0x0800)

#define ACPI_PDC_EST_CAPABILITY_SMP	(ACPI_PDC_SMP_C1PT | \
					 ACPI_PDC_C_C1_HALT | \
					 ACPI_PDC_P_FFH)

#define ACPI_PDC_EST_CAPABILITY_SWSMP	(ACPI_PDC_SMP_C1PT | \
					 ACPI_PDC_C_C1_HALT | \
					 ACPI_PDC_SMP_P_SWCOORD | \
					 ACPI_PDC_SMP_P_HWCOORD | \
					 ACPI_PDC_P_FFH)

#define ACPI_PDC_C_CAPABILITY_SMP	(ACPI_PDC_SMP_C2C3  | \
					 ACPI_PDC_SMP_C1PT  | \
					 ACPI_PDC_C_C1_HALT | \
					 ACPI_PDC_C_C1_FFH  | \
					 ACPI_PDC_C_C2C3_FFH)

#endif				/* __PDC_INTEL_H__ */