linux-kernel - Re: [PATCH] KVM: x86: Deflect unknown MSR accesses to user space

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Message-ID: <87y2n2log7.fsf@vitty.brq.redhat.com>
Date:   Wed, 29 Jul 2020 10:23:20 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>, Alexander Graf <graf@...zon.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm list <kvm@...r.kernel.org>,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Aaron Lewis <aaronlewis@...gle.com>
Subject: Re: [PATCH] KVM: x86: Deflect unknown MSR accesses to user space

Jim Mattson <jmattson@...gle.com> writes:

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