linux-kernel - Re: [PATCH -next] kvm/svm: disable KCSAN for svm_vcpu

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Message-ID: <f02ca9b9-f0a6-dfb5-1ca0-32a12d4f56fb@redhat.com>
Date:   Wed, 15 Apr 2020 17:57:07 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Qian Cai <cai@....pw>, paulmck@...nel.org
Cc:     elver@...gle.com, sean.j.christopherson@...el.com,
        kasan-dev@...glegroups.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] kvm/svm: disable KCSAN for svm_vcpu_run()

On 15/04/20 17:37, Qian Cai wrote:
> For some reasons, running a simple qemu-kvm command with KCSAN will
> reset AMD hosts. It turns out svm_vcpu_run() could not be instrumented.
> Disable it for now.
> 
>  # /usr/libexec/qemu-kvm -name ubuntu-18.04-server-cloudimg -cpu host
> 	-smp 2 -m 2G -hda ubuntu-18.04-server-cloudimg.qcow2
> 
> === console output ===
> Kernel 5.6.0-next-20200408+ on an x86_64
> 
> hp-dl385g10-05 login:
> 
> <...host reset...>
> 
> HPE ProLiant System BIOS A40 v1.20 (03/09/2018)
> (C) Copyright 1982-2018 Hewlett Packard Enterprise Development LP
> Early system initialization, please wait...
> 
> Signed-off-by: Qian Cai <cai@....pw>
> ---
>  arch/x86/kvm/svm/svm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 2be5bbae3a40..1fdb300e9337 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3278,7 +3278,7 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
>  
>  bool __svm_vcpu_run(unsigned long vmcb_pa, unsigned long *regs);
>  
> -static void svm_vcpu_run(struct kvm_vcpu *vcpu)
> +static __no_kcsan void svm_vcpu_run(struct kvm_vcpu *vcpu)
>  {
>  	struct vcpu_svm *svm = to_svm(vcpu);
>  
> 

I suppose you tested the patch to move cli/sti into the .S file.  Anyway:

Acked-by: Paolo Bonzini <pbonzini@...hat.com>

Thanks,

Paolo