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Subject: Re: [PATCH 1/2] KVM: vmx/pmu: Fix dummy check if lbr_desc->event is
 created
To:     Sean Christopherson <seanjc@google.com>,
        Like Xu <like.xu@linux.intel.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        x86@kernel.org, linux-kernel@vger.kernel.org
References: <20210223013958.1280444-1-like.xu@linux.intel.com>
 <YDU4II6Jt+E5nFmG@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <52a30738-08b5-740c-7c6e-b7a6edcbe552@redhat.com>
Date:   Tue, 23 Feb 2021 18:19:43 +0100
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On 23/02/21 18:15, Sean Christopherson wrote:
> If event
> creation fails in that flow, I would think KVM would do its best to create an
> event in future runs without waiting for additional actions from the guest.
> 
> Also, this bug suggests there's a big gaping hole in the test coverage.  AFAICT,
> event contention would lead to a #GP crash in the host due to lbr_desc->event
> being dereferenced, no?

Yes, testing contention would use the tools/testing/selftests/kvm 
framework rather than just kvm-unit-tests.

Paolo