> #ifdef CONFIG_PARAVIRT
> +/*
> + * Paravirt alternatives are applied much earlier than normal alternatives.
> + * They are only applied when running on a hypervisor. They replace some
> + * native instructions with calls to pv ops.
> + */
> +void __init apply_pv_alternatives(void)
> +{
> + setup_force_cpu_cap(X86_FEATURE_PV_OPS);
Not for Xen HVM guests.
> + apply_alternatives(__pv_alt_instructions, __pv_alt_instructions_end);
> +}
This is a problem (at least for Xen PV guests):
apply_alternatives()->text_poke_early()->local_irq_save()->...'cli'->death.
It might be possible not to turn off/on the interrupts in this
particular case since the guest probably won't be able to handle an
interrupt at this point anyway.
> +
> void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
> struct paravirt_patch_site *end)
> {
> diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c
> index 4fa90006ac68..17243fe0f5ce 100644
> --- a/arch/x86/kernel/cpu/hypervisor.c
> +++ b/arch/x86/kernel/cpu/hypervisor.c
> @@ -71,6 +71,8 @@ void __init init_hypervisor_platform(void)
> if (!x86_hyper)
> return;
>
> + apply_pv_alternatives();
Not for Xen PV guests who have already done this.
-boris
> +
> if (x86_hyper->init_platform)
> x86_hyper->init_platform();
> }
>
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