linux-kernel - Re: [PATCH] KVM: x86: Remove WARN sanity check on hypervisor timer vs. UNINITIALIZED vCPU

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: <ZNUDXsDaRwczONAu@google.com>
Date:   Thu, 10 Aug 2023 08:33:50 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yikebaer Aizezi <yikebaer61@...il.com>
Subject: Re: [PATCH] KVM: x86: Remove WARN sanity check on hypervisor timer
 vs. UNINITIALIZED vCPU

On Thu, Aug 10, 2023, Paolo Bonzini wrote:
> On 8/9/23 01:20, Sean Christopherson wrote:
> >   		/*
> > -		 * It should be impossible for the hypervisor timer to be in
> > -		 * use before KVM has ever run the vCPU.
> > +		 * Don't bother switching APIC timer emulation from the
> > +		 * hypervisor timer to the software timer, the only way for the
> > +		 * APIC timer to be active is if userspace stuffed vCPU state,
> > +		 * i.e. put the vCPU into a nonsensical state.  Only an INIT
> > +		 * will transition the vCPU out of UNINITIALIZED (without more
> > +		 * state stuffing from userspace), which will reset the local
> > +		 * APIC and thus smother the timer anyways, i.e. the APIC timer
> 
> "Cancel" is probably more understandable to non-native speakers, though
> undoubtedly less poetic.

I intentionally avoided "cancel" because there is no guaranteed the timer would
actually be canceled (if KVM switched to the software timer).  I am/was trying to
call out that even if the timer expires and pends an interrupts, the interrupt
will ultimately be dropped.

Maybe "squashed"?