Re: [PATCH 0/2] KVM: x86: Convert all runtime WARNs to ONCE

[Vitaly Kuznetsov]

Yosry Ahmed <yosry@xxxxxxxxxx> writes:

> On Mon, Oct 26, 2026 at 10:36 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>>
>> On Fri, Oct 23, 2026, Yosry Ahmed wrote:
>> > On Thu, Oct 22, 2026 at 2:55 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>> > >
>> > > Convert all bare WARN() and WARN_ON() runtime usage, i.e. WARNs that aren't
>> > > strictly scoped to module init/exit, or similar, to ONCE() variants for what
>> > > should be fairly obvious reasons at this point.
>> >
>> > Do you wanna CC stable?
>>
>> Not really?  Maybe?  I worry that this will generate an absurd number of conflicts
>> and also have "misses" in older kernels, to the point where it oculd do more harm
>> than good.
>>
>> I could be convinced this should be tagged for stable@, though honestly it might
>> be better to omit the automatic backport trigger and just rely on someone to
>> "manually" provide equivalent patches.
>
> I can just see this ultimately preventing a DoS and if it lands on any
> stable kernel it should be a win, but yeah probably manual backports
> are needed :/

With my backporter's hat on, it would help significantly if we split the
patch per-area (hyperv, [l]apic, posted_intr, vmx, svm,...). It would
also help those who want to analyze whether the particular WARN_ON() is
actually guest triggerable and open the corresponding CVEs.

-- 
Vitaly