linux-kernel - Re: [PATCH v5] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE

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] [day] [month] [year] [list]

Message-ID: <170199319421.1675545.670609241239795412.b4-ty@google.com>
Date:   Thu,  7 Dec 2023 18:17:39 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        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>,
        David Woodhouse <dwmw2@...radead.org>, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Paul Durrant <paul@....org>
Subject: Re: [PATCH v5] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT

On Thu, 02 Nov 2023 16:21:28 +0000, Paul Durrant wrote:
> Unless explicitly told to do so (by passing 'clocksource=tsc' and
> 'tsc=stable:socket', and then jumping through some hoops concerning
> potential CPU hotplug) Xen will never use TSC as its clocksource.
> Hence, by default, a Xen guest will not see PVCLOCK_TSC_STABLE_BIT set
> in either the primary or secondary pvclock memory areas. This has
> led to bugs in some guest kernels which only become evident if
> PVCLOCK_TSC_STABLE_BIT *is* set in the pvclocks. Hence, to support
> such guests, give the VMM a new Xen HVM config flag to tell KVM to
> forcibly clear the bit in the Xen pvclocks.
> 
> [...]

Applied to kvm-x86 xen (and not on a Friday!), thanks!

[1/1] KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT
      https://github.com/kvm-x86/linux/commit/6d7228352609

--
https://github.com/kvm-x86/linux/tree/next