x86: reduce redundancy in tsc_[gs]et_info() - some of the case statements are effectively or mostly special cases of others, so there's no good reason not to share the code - in the "get" function, a variable can be made case-wide instead of having multiple instance of it (and those even with a pointless initializer) - minor formatting adjustments Signed-off-by: Jan Beulich --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -1786,26 +1786,22 @@ void tsc_get_info(struct domain *d, uint switch ( *tsc_mode ) { + uint64_t tsc; + case TSC_MODE_NEVER_EMULATE: - *elapsed_nsec = *gtsc_khz = 0; + *elapsed_nsec = *gtsc_khz = 0; break; - case TSC_MODE_ALWAYS_EMULATE: - *elapsed_nsec = get_s_time() - d->arch.vtsc_offset; - *gtsc_khz = d->arch.tsc_khz; - break; case TSC_MODE_DEFAULT: if ( d->arch.vtsc ) { + case TSC_MODE_ALWAYS_EMULATE: *elapsed_nsec = get_s_time() - d->arch.vtsc_offset; *gtsc_khz = d->arch.tsc_khz; + break; } - else - { - uint64_t tsc = 0; - rdtscll(tsc); - *elapsed_nsec = scale_delta(tsc,&d->arch.vtsc_to_ns); - *gtsc_khz = cpu_khz; - } + rdtscll(tsc); + *elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns); + *gtsc_khz = cpu_khz; break; case TSC_MODE_PVRDTSCP: if ( d->arch.vtsc ) @@ -1815,10 +1811,9 @@ void tsc_get_info(struct domain *d, uint } else { - uint64_t tsc = 0; rdtscll(tsc); - *elapsed_nsec = (scale_delta(tsc,&d->arch.vtsc_to_ns) - - d->arch.vtsc_offset); + *elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns) - + d->arch.vtsc_offset; *gtsc_khz = 0; /* ignored by tsc_set_info */ } break; @@ -1875,28 +1870,24 @@ void tsc_set_info(struct domain *d, switch ( d->arch.tsc_mode = tsc_mode ) { - case TSC_MODE_NEVER_EMULATE: - d->arch.vtsc = 0; - break; - case TSC_MODE_ALWAYS_EMULATE: - d->arch.vtsc = 1; - d->arch.vtsc_offset = get_s_time() - elapsed_nsec; - d->arch.tsc_khz = gtsc_khz ? gtsc_khz : cpu_khz; - set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000 ); - d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns); - break; case TSC_MODE_DEFAULT: - d->arch.vtsc = 1; + case TSC_MODE_ALWAYS_EMULATE: d->arch.vtsc_offset = get_s_time() - elapsed_nsec; - d->arch.tsc_khz = gtsc_khz ? gtsc_khz : cpu_khz; - set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000 ); - /* use native TSC if initial host has safe TSC, has not migrated - * yet and tsc_khz == cpu_khz */ - if ( host_tsc_is_safe() && incarnation == 0 && - d->arch.tsc_khz == cpu_khz ) + d->arch.tsc_khz = gtsc_khz ?: cpu_khz; + set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000); + /* + * In default mode use native TSC if the host has safe TSC, + * the VM has not migrated yet, and tsc_khz == cpu_khz. + */ + if ( tsc_mode == TSC_MODE_DEFAULT && host_tsc_is_safe() && + incarnation == 0 && d->arch.tsc_khz == cpu_khz ) + { + case TSC_MODE_NEVER_EMULATE: d->arch.vtsc = 0; - else - d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns); + break; + } + d->arch.vtsc = 1; + d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns); break; case TSC_MODE_PVRDTSCP: d->arch.vtsc = boot_cpu_has(X86_FEATURE_RDTSCP) &&