linux-kernel - Re: [PATCH 06/13] KVM: monolithic: x86: remove __exit section prefix from machine

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Message-ID: <ccd2b1dc-ab23-2607-6f07-5429e7601282@redhat.com>
Date:   Tue, 5 Nov 2019 11:16:19 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Andrea Arcangeli <aarcange@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH 06/13] KVM: monolithic: x86: remove __exit section prefix
 from machine_unsetup

On 04/11/19 23:59, Andrea Arcangeli wrote:
> Adjusts the section prefixes of some KVM x86 code function because
> with the monolithic KVM model the section checker can now do a more
> accurate static analysis at build time and it found a potentially
> kernel crashing bug. This also allows to build without
> CONFIG_SECTION_MISMATCH_WARN_ONLY=n.
> 
> The __exit removed from machine_unsetup is because
> kvm_arch_hardware_unsetup() is called by kvm_init() which is in the
> __init section. It's not allowed to call a function located in the
> __exit section and dropped during the kernel link from the __init
> section or the kernel will crash if that call is made.
> 
> Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 4 ++--
>  arch/x86/kvm/svm.c              | 2 +-
>  arch/x86/kvm/vmx/vmx.c          | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index b36dd3265036..2b03ec80f6d7 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1004,7 +1004,7 @@ extern int kvm_x86_hardware_enable(void);
>  extern void kvm_x86_hardware_disable(void);
>  extern __init int kvm_x86_check_processor_compatibility(void);
>  extern __init int kvm_x86_hardware_setup(void);
> -extern __exit void kvm_x86_hardware_unsetup(void);
> +extern void kvm_x86_hardware_unsetup(void);
>  extern bool kvm_x86_cpu_has_accelerated_tpr(void);
>  extern bool kvm_x86_has_emulated_msr(int index);
>  extern void kvm_x86_cpuid_update(struct kvm_vcpu *vcpu);
> @@ -1196,7 +1196,7 @@ struct kvm_x86_ops {
>  	void (*hardware_disable)(void);
>  	int (*check_processor_compatibility)(void);/* __init */
>  	int (*hardware_setup)(void);               /* __init */
> -	void (*hardware_unsetup)(void);            /* __exit */
> +	void (*hardware_unsetup)(void);
>  	bool (*cpu_has_accelerated_tpr)(void);
>  	bool (*has_emulated_msr)(int index);
>  	void (*cpuid_update)(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 1705608246fb..4ce102f6f075 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1412,7 +1412,7 @@ __init int kvm_x86_hardware_setup(void)
>  	return r;
>  }
>  
> -__exit void kvm_x86_hardware_unsetup(void)
> +void kvm_x86_hardware_unsetup(void)
>  {
>  	int cpu;
>  
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 9c5f0c67b899..e406707381a4 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7737,7 +7737,7 @@ __init int kvm_x86_hardware_setup(void)
>  	return r;
>  }
>  
> -__exit void kvm_x86_hardware_unsetup(void)
> +void kvm_x86_hardware_unsetup(void)
>  {
>  	if (nested)
>  		nested_vmx_hardware_unsetup();
> 

Queued, thanks.

Paolo