Re: [patch 3/5] KVM: MMU: notifiers support for pinned sptes

[Gleb Natapov <gleb@minantech.com>]

On Thu, Jun 19, 2014 at 03:28:25PM -0300, Marcelo Tosatti wrote:
> On Thu, Jun 19, 2014 at 09:48:50AM +0300, Gleb Natapov wrote:
> > On Wed, Jun 18, 2014 at 08:12:06PM -0300, mtosatti@redhat.com wrote:
> > > Request KVM_REQ_MMU_RELOAD when deleting sptes from MMU notifiers.
> > > 
> > > Keep pinned sptes intact if page aging.
> > > 
> > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> > > 
> > > ---
> > >  arch/x86/kvm/mmu.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++-------
> > >  1 file changed, 62 insertions(+), 9 deletions(-)
> > > 
> > > Index: kvm.pinned-sptes/arch/x86/kvm/mmu.c
> > > ===================================================================
> > > --- kvm.pinned-sptes.orig/arch/x86/kvm/mmu.c	2014-06-18 17:28:24.339435654 -0300
> > > +++ kvm.pinned-sptes/arch/x86/kvm/mmu.c	2014-06-18 17:29:32.510225755 -0300
> > > @@ -1184,6 +1184,42 @@
> > >  		kvm_flush_remote_tlbs(vcpu->kvm);
> > >  }
> > >  
> > > +static void ack_flush(void *_completed)
> > > +{
> > > +}
> > > +
> > > +static void mmu_reload_pinned_vcpus(struct kvm *kvm)
> > > +{
> > > +	int i, cpu, me;
> > > +	cpumask_var_t cpus;
> > > +	struct kvm_vcpu *vcpu;
> > > +	unsigned int req = KVM_REQ_MMU_RELOAD;
> > > +
> > > +	zalloc_cpumask_var(&cpus, GFP_ATOMIC);
> > > +
> > > +	me = get_cpu();
> > > +	kvm_for_each_vcpu(i, vcpu, kvm) {
> > > +		if (list_empty(&vcpu->arch.pinned_mmu_pages))
> > > +			continue;
> > > +		kvm_make_request(req, vcpu);
> > > +		cpu = vcpu->cpu;
> > > +
> > > +		/* Set ->requests bit before we read ->mode */
> > > +		smp_mb();
> > > +
> > > +		if (cpus != NULL && cpu != -1 && cpu != me &&
> > > +		      kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE)
> > > +			cpumask_set_cpu(cpu, cpus);
> > > +	}
> > > +	if (unlikely(cpus == NULL))
> > > +		smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1);
> > > +	else if (!cpumask_empty(cpus))
> > > +		smp_call_function_many(cpus, ack_flush, NULL, 1);
> > > +	put_cpu();
> > > +	free_cpumask_var(cpus);
> > > +	return;
> > > +}
> > This is a c&p of make_all_cpus_request(), the only difference is checking
> > of vcpu->arch.pinned_mmu_pages.  You can add make_some_cpus_request(..., bool (*predicate)(struct kvm_vcpu *))
> > to kvm_main.c and rewrite make_all_cpus_request() to use it instead.
> 
> Half-way through it i decided it was better to c&p.
> 
> Can change make_all_cpus_request() though if it makes more sense to you.
> 
If I haven't missed anything and checking of pinned_mmu_pages is indeed the
only difference, then yes, reusing make_all_cpus_request() makes more sense.

--
			Gleb.