Re: [PATCH v6 00/51] x86: Try to wrangle PV clocks vs. TSC

[Borislav Petkov <bp@xxxxxxxxx>]

On November 4, 2026 7:37:50 PM UTC, Sean Christopherson <seanjc@xxxxxxxxxx> 
wrote:
>On Thu, Sep 10, 2026, David Woodhouse wrote:
>> On Thu, 2026-09-10 at 10:59 -0700, Sean Christopherson wrote:
>> > On Thu, Aug 06, 2026, Sean Christopherson wrote:
>> > > The primary goal of this series to fix flaws with SNP and TDX guests 
>> > > where a
>> > > PV clock provided by the untrusted hypervisor is used instead of the 
>> > > secure
>> > > TSC that is controlled by trusted firmware.
>> > > 
>> > > The secondary goal is modernize running under KVM.  Currently, KVM 
>> > > guests will
>> > > use TSC for clocksource, but not sched_clock.  And Linux-as-a-KVM-guest 
>> > > doesn't
>> > > support paravirt enumeration of the TSC/APIC frequencies, even though 
>> > > QEMU
>> > > provides that information by default.
>> > > 
>> > > The tertiary goal is to clean up the PV clock code to deduplicate logic 
>> > > across
>> > > hypervisors, and to hopefully make it all easier to maintain going 
>> > > forward.
>> > > 
>> > > The quaternary goal is to clean up the TSC calibration code, which was 
>> > > made
>> > > stupidly hard to follow by hypervisor code mixing in with the native
>> > > calibration routines, instead of being implemented as a pure alternative.
>> > > 
>> > > Note, the VMware and Xen changes still probably should get acks from 
>> > > those
>> > > maintainers, as my understanding of what they're trying to do may be 
>> > > flawed.
>> > 
>> > This (thankfully) still applies cleanly.  What can I do to help move this 
>> > forward?
>> 
>> Nudge Thomas to spot that this is guest-side and we want him to pick it up, 
>> I guess?
>
>Amazingly, still applies cleanly on 7.4-rc1 and tip/master.  I know we're 
>shortly
>after the merge window, but this has been sitting idle for months and addresses
>issues that are impacting a variety of end users.
>
>Note, this also provides meaningful hardening for SNP and TDX.  /me stares 
>intently
>in the direction of Dave and Boris.

Would you believe me if I told you you're in the "review" mbox?

The damn thing just keeps growing constantly :-/

I would love it if we had a review scoring thing like the net folks - whoever 
reviews others' patches, gets looked at first... and no, I don't mean you with 
that.

:)
-- 
Small device. Typos and formatting crap