Re: [patch V2 50/58] x86/apic: Provide common init infrastructure

[Juergen Gross]

On 01.08.23 10:54, Thomas Gleixner wrote:
> On Tue, Aug 01 2023 at 10:25, Juergen Gross wrote:
> > On 01.08.23 10:23, Thomas Gleixner wrote:
> > > On Tue, Aug 01 2023 at 09:37, Juergen Gross wrote:
> > > > On 01.08.23 09:32, Thomas Gleixner wrote:
> > > > > On Tue, Aug 01 2023 at 09:08, Juergen Gross wrote:
> > > > > > On 01.08.23 08:49, Juergen Gross wrote:
> > > > > >      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;
> > > > >
> > > > > I don't think this one is needed.
> > > >
> > > > Indeed.
> > >
> > > Can you send a real patch please which I can add to that pile at the
> > > right place?
> >
> > I think adding it right after patch 50 should be fine?
> >
> > The WARN() will be issued only with patch 58.
>
> Correct.

Here it is.


Juergen
From 6520d1d222511e675862d56fc07b020c1c334ebf Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Tue, 1 Aug 2023 10:50:42 +0200
Subject: [PATCH] x86/xen/apic: Use standard apic driver mechanism for Xen

Instead of setting the Xen PV apic driver very early during boot,
just use the standard apic driver probing by setting an appropriate
x86_init.irqs.intr_mode_init callback.

At the same time eliminate xen_apic_check() which has never been used.

The #ifdef CONFIG_X86_LOCAL_APIC around the call of xen_init_apic()
can be removed, too, as CONFIG_XEN depends on CONFIG_X86_LOCAL_APIC.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/xen/apic.c         | 11 -----------
 arch/x86/xen/enlighten_pv.c |  4 +---
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index 1838aefc632f..315ffd8d377f 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -158,19 +158,8 @@ static struct apic xen_pv_apic = {
 	.icr_write 			= xen_apic_icr_write,
 };
 
-static void __init xen_apic_check(void)
-{
-	apic_install_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;
 
-- 
2.35.3

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