Messages in this thread | | | Date | Fri, 9 Dec 2022 14:32:15 -0500 | From | Boris Ostrovsky <> | Subject | Re: [PATCH linux-next] x86/xen/time: prefer tsc as clocksource when it is invariant |
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On 12/8/22 11:36 AM, Krister Johansen wrote: > + /* > + * As Dom0 is never moved, no penalty on using TSC there. > + * > + * If the guest has invariant tsc, then set xen_clocksource rating > + * below that of the tsc so that the system prefers tsc instead. This > + * check excludes PV domains, because PV is unable to guarantee that the > + * guest's cpuid call has been intercepted by the hypervisor. > + */ > + if (xen_initial_domain()) { > xen_clocksource.rating = 275; > + } else if ((xen_hvm_domain() || xen_pvh_domain()) && > + boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && > + boot_cpu_has(X86_FEATURE_NONSTOP_TSC) && > + !check_tsc_unstable()) { > + xen_clocksource.rating = 299; > + }
What if RDTSC is intercepted?
-boris
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