From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754184Ab2GIO1l (ORCPT ); Mon, 9 Jul 2012 10:27:41 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:38049 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349Ab2GIO1j (ORCPT ); Mon, 9 Jul 2012 10:27:39 -0400 Date: Mon, 9 Jul 2012 10:19:15 -0400 From: Konrad Rzeszutek Wilk To: Stefano Stabellini Cc: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" Subject: Re: [Xen-devel] [PATCH] xen/events: fix unmask_evtchn for PV on HVM guests Message-ID: <20120709141915.GB9580@phenom.dumpdata.com> References: <1340381685-22529-1-git-send-email-stefano.stabellini@eu.citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 22, 2012 at 05:26:07PM +0100, Stefano Stabellini wrote: > When unmask_evtchn is called, if we already have an event pending, we > just set evtchn_pending_sel waiting for local_irq_enable to be called. > That is because PV guests set the irq_enable pvops to Can you point out where the PV guests do that please? Even just including a snippet of code would be nice so that somebody in the future has an idea of where it was/is. > xen_irq_enable_direct that also handles pending events. > > However HVM guests (and ARM guests) do not change or do not have the > irq_enable pvop, so evtchn_unmask cannot work properly for them. Duh! > > Considering that having the pending_irq bit set when unmask_evtchn is > called is not very common, and it is simpler to keep the Unless you pin the guests on the vCPUS on which domain0 is not present.. > native_irq_enable implementation for HVM guests (and ARM guests), the > best thing to do is just use the EVTCHNOP_unmask hypercall (Xen > re-injects pending events in response). And by re-injects you mean than the IOAPIC or (whatever it is on ARM) is armed to show that there is a pending interrupt, right? > > Signed-off-by: Stefano Stabellini > --- > drivers/xen/events.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/xen/events.c b/drivers/xen/events.c > index eae0d0b..0132505 100644 > --- a/drivers/xen/events.c > +++ b/drivers/xen/events.c > @@ -372,8 +372,11 @@ static void unmask_evtchn(int port) > > BUG_ON(!irqs_disabled()); > > - /* Slow path (hypercall) if this is a non-local port. */ > - if (unlikely(cpu != cpu_from_evtchn(port))) { > + /* Slow path (hypercall) if this is a non-local port or if this is > + * an hvm domain and an event is pending (hvm domains don't have > + * their own implementation of irq_enable). */ > + if (unlikely((cpu != cpu_from_evtchn(port)) || > + (xen_hvm_domain() && sync_test_bit(port, &s->evtchn_pending[0])))) { > struct evtchn_unmask unmask = { .port = port }; We already have two seperate acks - for when there is an GMFN APIC bitmap and when there is not. Can we also have to seperate unmask_evtchn then? And just have the HVM and ARM just do a straightforward unmaks_evtchn while the PV remains the same? > (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); > } else { >