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Subject: Re: [RFC PATCH 1/3] kvm: x86: Rename KVM_DEBUGREG_RELOAD to
 KVM_DEBUGREG_NEED_RELOAD
To:     Nadav Amit <nadav.amit@gmail.com>
Cc:     Xiaoyao Li <xiaoyao.li@intel.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        kvm <kvm@vger.kernel.org>, Nadav Amit <namit@cs.technion.ac.il>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        linux-kernel@vger.kernel.org
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 <20200416101509.73526-2-xiaoyao.li@intel.com>
 <85cb5946-2109-28a0-578d-bed31d1b8298@redhat.com>
 <08C6D1FB-A4F7-49FA-AC46-5323C104840A@gmail.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <8223a7e2-5d4a-b427-c44f-d76450f16748@redhat.com>
Date:   Sat, 25 Apr 2020 21:16:14 +0200
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On 25/04/20 18:54, Nadav Amit wrote:
>> I wonder if KVM_DEBUGREG_RELOAD is needed at all.  It should be easy to
>> write selftests for it, using the testcase in commit message
>> 172b2386ed16 and the information in commit ae561edeb421.
> I must be missing something, since I did not follow this thread and other
> KVM changes very closely.
> 
> Yet, for the record, I added KVM_DEBUGREG_RELOAD due to real experienced
> issues that I had while running Intel’s fuzzing tests on KVM: IIRC, the DRs
> were not reloaded after an INIT event that clears them.

Indeed, but the code has changed since then and I'm not sure it is still
needed.

> Personally, I would prefer that a test for that, if added, would be added
> to KVM-unit-tests, based on Liran’s INIT test. This would allow to confirm
> bare-metal behaves as the VM.

Yes, that would be good as well of course.

Paolo