Re: [RFC KVM 18/27] kvm/isolation: function to copy page table entries for percpu buffer

[Peter Zijlstra]

On Tue, May 14, 2019 at 06:24:48PM +0200, Alexandre Chartre wrote:
> On 5/14/19 5:23 PM, Andy Lutomirski wrote:

> > How important is the ability to enable IRQs while running with the KVM
> > page tables?
> > 
> 
> I can't say, I would need to check but we probably need IRQs at least for
> some timers. Sounds like you would really prefer IRQs to be disabled.
> 

I think what amluto is getting at, is:

again:
	local_irq_disable();
	switch_to_kvm_mm();
	/* do very little -- (A) */
	VMEnter()

		/* runs as guest */

	/* IRQ happens */
	WMExit()
	/* inspect exit raisin */
	if (/* IRQ pending */) {
		switch_from_kvm_mm();
		local_irq_restore();
		goto again;
	}


but I don't know anything about VMX/SVM at all, so the above might not
be feasible, specifically I read something about how VMX allows NMIs
where SVM did not somewhere around (A) -- or something like that,
earlier in this thread.