linux-kernel - Re: [PATCH v3 1/5] x86/paravirt: move some functions and defines to alternative

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Message-ID: <3b6a8d5d-f766-49fd-aa35-992c5b048bc6@suse.com>
Date:   Mon, 30 Oct 2023 13:39:27 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ajay Kaher <akaher@...are.com>,
        Alexey Makhalov <amakhalov@...are.com>,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 1/5] x86/paravirt: move some functions and defines to
 alternative

On 25.10.23 12:34, Borislav Petkov wrote:
> On Thu, Oct 19, 2023 at 11:15:16AM +0200, Juergen Gross wrote:
>> +/* Low-level backend functions usable from alternative code replacements. */
>> +DEFINE_ASM_FUNC(x86_nop, "", .entry.text);
>> +EXPORT_SYMBOL_GPL(x86_nop);
> 
> This is all x86 code so you don't really need the "x86_" prefix - "nop"
> is perfectly fine.
> 
>> +noinstr void x86_BUG(void)
>> +{
>> +	BUG();
>> +}
>> +EXPORT_SYMBOL_GPL(x86_BUG);
> 
> That export is needed for?
> 
> Paravirt stuff in modules?
> 
> It builds here without it - I guess I need to do an allmodconfig.
> 

Turns out it is needed after all. With patch 4 applied I get:

ERROR: modpost: "BUG_func" [arch/x86/events/amd/power.ko] undefined!
ERROR: modpost: "BUG_func" [arch/x86/kernel/cpu/mce/mce-inject.ko] undefined!
ERROR: modpost: "BUG_func" [arch/x86/kernel/cpuid.ko] undefined!
ERROR: modpost: "BUG_func" [arch/x86/kvm/kvm.ko] undefined!
ERROR: modpost: "BUG_func" [arch/x86/kvm/kvm-intel.ko] undefined!
ERROR: modpost: "BUG_func" [arch/x86/kvm/kvm-amd.ko] undefined!
ERROR: modpost: "BUG_func" [fs/nfsd/nfsd.ko] undefined!
ERROR: modpost: "BUG_func" [crypto/aes_ti.ko] undefined!
ERROR: modpost: "BUG_func" [drivers/video/fbdev/uvesafb.ko] undefined!
ERROR: modpost: "BUG_func" [drivers/video/vgastate.ko] undefined!


Juergen

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