linux-kernel - Re: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V

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: <87mteei7yf.fsf@redhat.com>
Date:   Wed, 15 Jun 2022 11:36:56 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     mail@...rudhrb.com, kumarpraveen@...ux.microsoft.com,
        wei.liu@...nel.org, robert.bradford@...el.com, liuwe@...rosoft.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Ilias Stamatis <ilstam@...zon.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V

Anirudh Rayabharam <anrayabh@...ux.microsoft.com> writes:

> On Tue, Jun 14, 2022 at 07:20:34PM +0200, Paolo Bonzini wrote:
>> On 6/14/22 14:19, Vitaly Kuznetsov wrote:
>> > The latest version:
>> > https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/datatypes/hv_vmx_enlightened_vmcs
>> > 
>> > has it, actually. It was missing before (compare with e.g. 6.0b version
>> > here:
>> > https://github.com/MicrosoftDocs/Virtualization-Documentation/raw/live/tlfs/Hypervisor%20Top%20Level%20Functional%20Specification%20v6.0b.pdf)
>> > 
>> > but AFAIR TSC scaling wasn't advertised by genuine Hyper-V either.
>> > Interestingly enough, eVMCS version didn't change when these fields were
>> > added, it is still '1'.
>> > 
>> > I even have a patch in my stash (attached). I didn't send it out because
>> > it wasn't properly tested with different Hyper-V versions.
>> > 
>> > -- Vitaly
>> 
>> Anirudh, can you check if Vitaly's patches work for you?
>
> I will check it. But I wonder if they fit the criteria for inclusion in
> stable trees...
>
> It is important for the fix to land in the stable trees since this issue
> is a regression that was introduced _after_ 5.13. (I probably should've
> mentioned this in the changelog.)
>

Personally, I see no problem with splitting off TscMultiplier part from
my patch and marking it for stable@ fixing d041b5ea93352. I'm going to
run some tests too.

-- 
Vitaly