RE: [patch V3 00/60] x86/apic: Decrapification and static calls

[Michael Kelley (LINUX)]

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Sent: Tuesday, August 1, 2023 3:47 AM
> 
> Hi!
> 
> This is the follow up to:
> 
> 
> https://lore.kernel.org/lkml/20230724131206.500814398@xxxxxxxxxxxxx/
> 
> which addresses the XEN PV fallout decoded by Juergen.
> 
> TLDR: This cleans up accrued and partially unused gunk in order to convert
> the APIC callbacks to static calls.
> 
> The changes vs. V2:
> 
>   - Unbreak XEN/PV - Juergen
> 
>     Resulting delta patch below.
> 
>   - Rebased to 6.5-rc4 in preparation for the CPUID overhaul on top, which
>     has some collisions due to the recent mitigation muck.
> 
> The series is also available from git:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git apic-static-call-v3
> 
> Thanks,
> 
> 	tglx
> ---
> diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
> index 468406f511ff..7ad91225fdf4 100644
> --- a/arch/x86/xen/apic.c
> +++ b/arch/x86/xen/apic.c
> @@ -155,20 +155,9 @@ static struct apic xen_pv_apic __ro_after_init = {
>  	.icr_read			= xen_apic_icr_read,
>  	.icr_write			= xen_apic_icr_write,
>  };
> -
> -static void __init xen_apic_check(void)
> -{
> -	apic_install_driver(&xen_pv_apic);
> -}
> +apic_driver(xen_pv_apic);
> 
>  void __init xen_init_apic(void)
>  {
>  	x86_apic_ops.io_apic_read = xen_io_apic_read;
> -	/* On PV guests the APIC CPUID bit is disabled so none of the
> -	 * routines end up executing. */
> -	if (!xen_initial_domain())
> -		apic_install_driver(&xen_pv_apic);
> -
> -	x86_platform.apic_post_init = xen_apic_check;
>  }
> -apic_driver(xen_pv_apic);
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 93b658248d01..c393c44892ac 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -1326,7 +1326,7 @@ asmlinkage __visible void __init xen_start_kernel(struct
> start_info *si)
> 
>  	x86_init.resources.memory_setup = xen_memory_setup;
>  	x86_init.irqs.intr_mode_select	= x86_init_noop;
> -	x86_init.irqs.intr_mode_init	= x86_init_noop;
> +	x86_init.irqs.intr_mode_init	= x86_64_probe_apic;
>  	x86_init.oem.arch_setup = xen_arch_setup;
>  	x86_init.oem.banner = xen_banner;
>  	x86_init.hyper.init_platform = xen_pv_init_platform;
> @@ -1366,12 +1366,10 @@ asmlinkage __visible void __init xen_start_kernel(struct
> start_info *si)
> 
>  	xen_init_capabilities();
> 
> -#ifdef CONFIG_X86_LOCAL_APIC
>  	/*
>  	 * set up the basic apic ops.
>  	 */
>  	xen_init_apic();
> -#endif
> 
>  	machine_ops = xen_machine_ops;
> 
> diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
> index c6b42c66c60c..a0f07bbfcd6e 100644
> --- a/arch/x86/xen/smp_pv.c
> +++ b/arch/x86/xen/smp_pv.c
> @@ -182,7 +182,8 @@ static void __init _get_smp_config(unsigned int early)
>  	if (subtract)
>  		set_nr_cpu_ids(nr_cpu_ids - subtract);
>  #endif
> -
> +	/* Pretend to be a proper enumerated system */
> +	smp_found_config = 1;
>  }
> 
>  static void __init xen_pv_smp_prepare_boot_cpu(void)
> 

Entire series tested implicitly on Hyper-V guests as part of
testing the topology series with the scope described here:
https://lore.kernel.org/lkml/BYAPR21MB16884A9AE4AF581B0B1CDB25D708A@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#mf6ccf50e65e214cd6d8ba3e683873bf4139259a1

Tested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>