Re: [PATCH v2 11/49] KVM: x86: Disallow KVM_CAP_X86_DISABLE_EXITS after vCPU creation

[Maxim Levitsky]

On Mon, 2024-07-08 at 19:43 +0000, Sean Christopherson wrote:
> On Thu, Jul 04, 2024, Maxim Levitsky wrote:
> > On Fri, 2024-05-17 at 10:38 -0700, Sean Christopherson wrote:
> > > Reject KVM_CAP_X86_DISABLE_EXITS if vCPUs have been created, as disabling
> > > PAUSE/MWAIT/HLT exits after vCPUs have been created is broken and useless,
> > > e.g. except for PAUSE on SVM, the relevant intercepts aren't updated after
> > > vCPU creation.  vCPUs may also end up with an inconsistent configuration
> > > if exits are disabled between creation of multiple vCPUs.
> > 
> > Hi,
> > 
> > I am not sure that PAUSE intercepts are updated either, I wasn't able to find a code
> > that does this.
> > 
> > I agree with this change, but note that there was some talk on the mailing
> > list to allow to selectively disable VM exits (e.g PAUSE, MWAIT, ...) only on
> > some vCPUs, based on the claim that some vCPUs might run RT tasks, while some
> > might be housekeeping.  I haven't followed those discussions closely.
> 
> This change is actually pulled from that series[*].  IIRC, v1 of that series
> didn't close the VM-scoped hole, and the overall code was much more complex as
> a result.
> 
> [*] https://lore.kernel.org/all/20230121020738.2973-2-kechenl@xxxxxxxxxx
> 

Hi,
Thanks for the pointer, I searched for this patch series in many places but I couldn't find it.
Any idea what happened with this patch series btw?

Best regards,
	Maxim Levitsky