linux-kernel - Re: [PATCH 2/2] KVM: VMX: Add knob to allow rejecting kvm

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Message-ID: <8288b833-68f0-9fd2-d4d4-21cc9aff5ec2@redhat.com>
Date:   Thu, 26 May 2022 12:39:51 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Chenyi Qiang <chenyi.qiang@...el.com>,
        Lei Wang <lei4.wang@...el.com>
Subject: Re: [PATCH 2/2] KVM: VMX: Add knob to allow rejecting kvm_intel on
 inconsistent VMCS config

On 5/25/22 23:04, Sean Christopherson wrote:
> Add an off-by-default module param, reject_inconsistent_vmcs_config, to
> allow rejecting the load of kvm_intel if an inconsistent VMCS config is
> detected.  Continuing on with an inconsistent, degraded config is
> undesirable when the CPU is expected to support a given set of features,
> e.g. can result in a misconfigured VM if userspace doesn't cross-check
> KVM_GET_SUPPORTED_CPUID, and/or can result in poor performance due to
> lack of fast MSR switching.
> 
> Signed-off-by: Sean Christopherson<seanjc@...gle.com>
> ---
>   arch/x86/kvm/vmx/vmx.c | 20 +++++++++++++++++---
>   1 file changed, 17 insertions(+), 3 deletions(-)

Yeah let's do this by default.

Paolo