linux-kernel - [patch V3 00/60] x86/apic: Decrapification and static calls

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Message-ID: <20230801103042.936020332@linutronix.de>
Date:   Tue,  1 Aug 2023 12:46:41 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Andrew Cooper <andrew.cooper3@...rix.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wei Liu <wei.liu@...nel.org>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Juergen Gross <jgross@...e.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Peter Keresztes Schmidt <peter@...esztesschmidt.de>
Subject: [patch V3 00/60] x86/apic: Decrapification and static calls

Hi!

This is the follow up to:

  https://lore.kernel.org/lkml/20230724131206.500814398@linutronix.de

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)