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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Jim Mattson <jmattson@google.com>, Alexander Graf <graf@amazon.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>, kvm list <kvm@vger.kernel.org>,
        linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Aaron Lewis <aaronlewis@google.com>
Subject: Re: [PATCH] KVM: x86: Deflect unknown MSR accesses to user space
In-Reply-To: <CALMp9eQ3OxhQZYiHPiebX=KyvjWQgxQEO-owjSoxgPKsOMRvjw@mail.gmail.com>
References: <20200728004446.932-1-graf@amazon.com> <87d04gm4ws.fsf@vitty.brq.redhat.com> <a1f30fc8-09f5-fe2f-39e2-136b881ed15a@amazon.com> <CALMp9eQ3OxhQZYiHPiebX=KyvjWQgxQEO-owjSoxgPKsOMRvjw@mail.gmail.com>
Date:   Wed, 29 Jul 2020 10:23:20 +0200
Message-ID: <87y2n2log7.fsf@vitty.brq.redhat.com>
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Jim Mattson <jmattson@google.com> writes:

> On Tue, Jul 28, 2020 at 5:41 AM Alexander Graf <graf@amazon.com> wrote:
>>

...

>> While it does feel a bit overengineered, it would solve the problem that
>> we're turning in-KVM handled MSRs into an ABI.
>
> It seems unlikely that userspace is going to know what to do with a
> large number of MSRs. I suspect that a small enumerated list will
> suffice.

The list can also be 'wildcarded', i.e. 
{
 u32 index;
 u32 mask;
 ...
}

to make it really short.

-- 
Vitaly