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f897e60a12
Some newer machines do not advertise legacy timers. The kernel can handle that situation if the TSC and the CPU frequency are enumerated by CPUID or MSRs and the CPU supports TSC deadline timer. If the CPU does not support TSC deadline timer the local APIC timer frequency has to be known as well. Some Ryzens machines do not advertize legacy timers, but there is no reliable way to determine the bus frequency which feeds the local APIC timer when the machine allows overclocking of that frequency. As there is no legacy timer the local APIC timer calibration crashes due to a NULL pointer dereference when accessing the not installed global clock event device. Switch the calibration loop to a non interrupt based one, which polls either TSC (if frequency is known) or jiffies. The latter requires a global clockevent. As the machines which do not have a global clockevent installed have a known TSC frequency this is a non issue. For older machines where TSC frequency is not known, there is no known case where the legacy timers do not exist as that would have been reported long ago. Reported-by: Daniel Drake <drake@endlessm.com> Reported-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Daniel Drake <drake@endlessm.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908091443030.21433@nanos.tec.linutronix.de Link: http://bugzilla.opensuse.org/show_bug.cgi?id=1142926#c12 |
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