linux-kernel - Re: [PATCH v2 2/3] KVM: X86: Fix userspace set broken combinations of CPUID and CR4

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Message-ID: <d0c35f21-b262-2c4e-9109-4ab803487705@redhat.com>
Date:   Tue, 24 Sep 2019 15:55:38 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <kernellwp@...il.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, stable@...r.kernel.org
Subject: Re: [PATCH v2 2/3] KVM: X86: Fix userspace set broken combinations of
 CPUID and CR4

On 17/09/19 19:32, Sean Christopherson wrote:
> 
> Paolo, can you provide an "official" ruling on how KVM_SET_SREGS should
> interact with reserved bits?  It's not at all clear from the git history
> if skipping the checks was intentional or an oversight.

It's okay to make it fail as long as KVM already checks the value of the
reserved bits on vmexit.  If not, some care might be required.

Paolo