linux-kernel - Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <61622212-4f7a-bf24-dab2-a40f2142835d@redhat.com>
Date:   Wed, 13 Jan 2021 13:40:20 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Wei Huang <wei.huang2@....com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        vkuznets@...hat.com, joro@...tes.org, bp@...en8.de,
        tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
        jmattson@...gle.com, wanpengli@...cent.com, bsd@...hat.com,
        dgilbert@...hat.com, mlevitsk@...hat.com
Subject: Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by
 VM instructions

On 12/01/21 18:59, Sean Christopherson wrote:
>> It would be very helpful to list exactly which CPUs are/aren't affected, even if
>> that just means stating something like "all CPUs before XYZ".  Given patch 2/2,
>> I assume it's all CPUs without the new CPUID flag?
> Ah, despite calling this an 'errata', the bad behavior is explicitly documented
> in the APM, i.e. it's an architecture bug, not a silicon bug.

I would still call it an errata for the case when virtualized 
VMSAVE/VMLOAD is enabled (and therefore VMLOAD intercepts are disabled). 
  In that case, the problem is that the GPA does not go through NPT 
before it is checked against *host* reserved memory regions.

In fact I hope that,  on processors that have the fix, VMSAVE/VMLOAD 
from guest mode _does_ check the GPA after it's been translated!

Paolo