From 0731a56c7c72fc117b69982e002954645fc3685b Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 24 Jan 2022 08:38:55 +0100 Subject: [PATCH] x86/APIC: no need for timer calibration when using TDT The only global effect of calibrate_APIC_clock() is the setting of "bus_scale"; the final __setup_APIC_LVTT(0) is (at best) redundant with the immediately following setup_APIC_timer() invocation. Yet "bus_scale" isn't used when using TDT. Avoid wasting 100ms for calibration in this case. Signed-off-by: Jan Beulich Acked-by: Andrew Cooper --- xen/arch/x86/apic.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c index d7d5c15155..5d3e1f3952 100644 --- a/xen/arch/x86/apic.c +++ b/xen/arch/x86/apic.c @@ -1292,11 +1292,15 @@ void __init setup_boot_APIC_clock(void) check_deadline_errata(); + if ( !boot_cpu_has(X86_FEATURE_TSC_DEADLINE) ) + tdt_enable = false; + local_irq_save(flags); - calibrate_APIC_clock(); + if ( !tdt_enable || apic_verbosity ) + calibrate_APIC_clock(); - if ( tdt_enable && boot_cpu_has(X86_FEATURE_TSC_DEADLINE) ) + if ( tdt_enable ) { printk(KERN_DEBUG "TSC deadline timer enabled\n"); tdt_enabled = true; -- 2.30.2