simple_udelay_calibration() relies on x86_platform's calibration ops. For KVM these ops are set late in setup_arch() and so simple_udelay_calibration() ends up using native version.
Besides being possibly incorrect, this significantly increases kernel boot time. For example, on my laptop executing start_kernel() by a guest takes ~10 times more than when KVM's ops are used. Since early_xdbc_setup_hardware() relies on calibration having been performed move it too. Signed-off-by: Boris Ostrovsky <[email protected]> --- v2: * Move xdbc initialization down as well. Alternatively, we could start calling simple_udelay_calibration() only on bare metal: My understanding is that the only reason it exists is to help with USB3 earlyprink driver, which I don't think is useful to guests anyway. arch/x86/kernel/setup.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f81823695014..6e0e747d53bf 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1039,8 +1039,6 @@ void __init setup_arch(char **cmdline_p) */ init_hypervisor_platform(); - simple_udelay_calibration(); - x86_init.resources.probe_roms(); /* after parse_early_param, so could debug it */ @@ -1118,9 +1116,6 @@ void __init setup_arch(char **cmdline_p) memblock_set_current_limit(ISA_END_ADDRESS); e820__memblock_setup(); - if (!early_xdbc_setup_hardware()) - early_xdbc_register_console(); - reserve_bios_regions(); if (efi_enabled(EFI_MEMMAP)) { @@ -1221,6 +1216,10 @@ void __init setup_arch(char **cmdline_p) kvmclock_init(); #endif + simple_udelay_calibration(); + if (!early_xdbc_setup_hardware()) + early_xdbc_register_console(); + x86_init.paging.pagetable_init(); kasan_init(); -- 2.11.0
