linux-kernel - Re: [PATCH] KVM: nVMX: Filter out all unsupported controls when eVMCS was activated

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Message-ID: <87v93a2pu9.fsf@vitty.brq.redhat.com>
Date:   Thu, 09 Sep 2021 09:03:10 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: nVMX: Filter out all unsupported controls when
 eVMCS was activated

Sean Christopherson <seanjc@...gle.com> writes:

> On Tue, Sep 07, 2021, Vitaly Kuznetsov wrote:
>> Let's be bold this time and instead of playing whack-a-mole just filter out
>> all unsupported controls from VMX MSRs.
>
> Out of curiosity, why didn't we do this from the get-go?

We actually did, the initial implementation (57b119da3594f) was
filtering out everything but then things changed in "only clear controls
which are known to cause issues" (31de3d2500e4). I forgot everything
already but was able to google this suggestion from Paolo:

https://www.lkml.org/lkml/2020/1/22/1108

so finally we've settled on a shortened list. Now as new Windows version
is out, we have new problems to solve)

-- 
Vitaly