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

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Date:   Fri, 17 Apr 2020 08:17:34 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Qian Cai <cai@....pw>
Cc:     Elver Marco <elver@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        kasan-dev <kasan-dev@...glegroups.com>, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH -next] kvm/svm: disable KCSAN for svm_vcpu_run()

On Fri, Apr 17, 2020 at 09:21:59AM -0400, Qian Cai wrote:
> 
> 
> > On Apr 15, 2020, at 11:57 AM, Paolo Bonzini <pbonzini@...hat.com> wrote:
> > 
> > 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>
> 
> Paul, can you pick this up along with other KCSAN fixes?

Queued and pushed, thank you both!

							Thanx, Paul