Messages in this thread | | | Subject | Re: [PATCH 11/13] x86/paravirt: Add paravirt alternatives infrastructure | From | Boris Ostrovsky <> | Date | Thu, 5 Oct 2017 16:35:03 -0400 |
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> #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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