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Date:   Thu, 25 May 2023 08:55:29 -0700
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Subject: Re: [PATCH v2 7/7] KVM: selftests: Test pmu event filter with
 incompatible kvm_pmu_event_filter
From:   Sean Christopherson <seanjc@google.com>
To:     Jinrong Liang <ljr.kernel@gmail.com>
Cc:     Like Xu <like.xu.linux@gmail.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Shuah Khan <shuah@kernel.org>,
        Aaron Lewis <aaronlewis@google.com>,
        David Matlack <dmatlack@google.com>,
        Vishal Annapurve <vannapurve@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Bagas Sanjaya <bagasdotme@gmail.com>,
        Jinrong Liang <cloudliang@tencent.com>,
        linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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On Thu, May 25, 2023, Jinrong Liang wrote:
> Sean Christopherson <seanjc@google.com> =E4=BA=8E2023=E5=B9=B45=E6=9C=882=
5=E6=97=A5=E5=91=A8=E5=9B=9B 07:50=E5=86=99=E9=81=93=EF=BC=9A
> > > +static uint64_t test_incompatible_filter(struct kvm_vcpu *vcpu, uint=
32_t action,
> > > +                                      uint32_t bitmap)
> > > +{
> > > +     struct incompatible_pmu_event_filter err_f;
> > > +
> > > +     err_f.action =3D action;
> > > +     err_f.fixed_counter_bitmap =3D bitmap;
> > > +     ioctl((vcpu->vm)->fd, KVM_SET_PMU_EVENT_FILTER, &err_f.action);
> >
> > This is completely busted.  It "passes" by luck, not because it's a val=
id test.
> > The size of the argument is embedded in the IOCTL number itself, which =
means that
> > unless glibc is being very nice and using a macro + typeof + sizeof to =
sanity check
> > things, which I highly doubt is the case, this ioctl() is passing rando=
m stack data,
> > a.k.a. garbage, to KVM.
> >
> > In short, drop this patch.
>=20
> Thank you for letting us know about the issues with the patch. I will
> drop the patch as suggested. Would you advise me to prepare version 3
> to remove this patch?

More comments on the other patches are incoming, please hold off on v3 unti=
l then.