linux-kernel - Re: [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4a4b9fea4937da7b0b42e6f3179566d73bf022e2.camel@redhat.com>
Date:   Mon, 10 May 2021 11:08:34 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Reiji Watanabe <reijiw@...gle.com>
Subject: Re: [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be
 disabled in the guest

On Tue, 2021-05-04 at 14:58 -0700, Jim Mattson wrote:
> On Tue, May 4, 2021 at 2:57 PM Paolo Bonzini <pbonzini@...hat.com> wrote:
> > On 04/05/21 23:53, Sean Christopherson wrote:
> > > > Does the right thing happen here if the vCPU is in guest mode when
> > > > userspace decides to toggle the CPUID.80000001H:EDX.RDTSCP bit on or
> > > > off?
> > > I hate our terminology.  By "guest mode", do you mean running the vCPU, or do
> > > you specifically mean running in L2?
> > > 
> > 
> > Guest mode should mean L2.
> > 
> > (I wonder if we should have a capability that says "KVM_SET_CPUID2 can
> > only be called prior to KVM_RUN").
> 
> It would certainly make it easier to reason about potential security issues.
> 
I vote too for this.
Best regards,
	Maxim Levitsky