Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: iGhMXsEFZ7rmehllBU/6DXbQhQ9ceJjM/OTGQL0+l9iOw433CMybv2oqS2CGcWtQPX5PXSPwfO
 aV5zYwDbdVxA==
Subject: Re: [PATCH] KVM: x86: Deflect unknown MSR accesses to user space
To:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Jim Mattson <jmattson@google.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>
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>
 <87y2n2log7.fsf@vitty.brq.redhat.com>
From:   Alexander Graf <graf@amazon.com>
Message-ID: <173948e8-4c7a-6dc4-de17-99151bc56d91@amazon.com>
Date:   Wed, 29 Jul 2020 11:09:26 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0)
 Gecko/20100101 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <87y2n2log7.fsf@vitty.brq.redhat.com>
Content-Language: en-US
Content-Type: text/plain; charset="windows-1252"; format="flowed"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 29.07.20 10:23, Vitaly Kuznetsov wrote:
> =

> =

> =

> 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.

I like the idea of wildcards, but I can't quite wrap my head around how =

we would implement ignore_msrs in user space with them?


Alex


Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879