From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: Re: [PATCH] xen/events: Always allocate legacy interrupts on PV guests Date: Wed, 18 Nov 2015 12:16:28 +0100 Message-ID: <87lh9vv9pv.fsf__41738.9827817262$1447845483$gmane$org@vitty.brq.redhat.com> References: <1447774585-21857-1-git-send-email-boris.ostrovsky@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1447774585-21857-1-git-send-email-boris.ostrovsky@oracle.com> (Boris Ostrovsky's message of "Tue, 17 Nov 2015 10:36:25 -0500") List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Boris Ostrovsky Cc: jgross@suse.com, linux-kernel@vger.kernel.org, xen-devel@lists.xen.org, david.vrabel@citrix.com, tglx@linutronix.de List-Id: xen-devel@lists.xenproject.org Boris Ostrovsky writes: > After commit 8c058b0b9c34 ("x86/irq: Probe for PIC presence before > allocating descs for legacy IRQs") early_irq_init() will no longer > preallocate descriptors for legacy interrupts if PIT does not > exist. PIC? > > Therefore we need to allocate those descriptors for PV guests > ourselves. > > Signed-off-by: Boris Ostrovsky > Suggested-by: Thomas Gleixner > --- > drivers/xen/events/events_base.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c > index 849500e..a2bb333 100644 > --- a/drivers/xen/events/events_base.c > +++ b/drivers/xen/events/events_base.c > @@ -419,8 +419,8 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi) > if (xen_pv_domain() && !xen_initial_domain()) > return xen_allocate_irq_dynamic(); > > - /* Legacy IRQ descriptors are already allocated by the arch. */ > - if (gsi < NR_IRQS_LEGACY) > + /* On HVM legacy IRQ descriptors are already allocated by the arch. */ > + if (xen_hvm_domain() && gsi < NR_IRQS_LEGACY) > irq = gsi; Wouldn't it be better to write it as if (gsi < nr_legacy_irqs()) ? I think it's possible to have PIC-less HVM guests in future (btw, what about HVMlite?). I see nr_legacy_irqs() is x86-only but it can easily be defined to NR_IRQS_LEGACY on other arches. > else > irq = irq_alloc_desc_at(gsi, -1); > @@ -445,8 +445,8 @@ static void xen_free_irq(unsigned irq) > > kfree(info); > > - /* Legacy IRQ descriptors are managed by the arch. */ > - if (irq < NR_IRQS_LEGACY) > + /* On HVM legacy IRQ descriptors are managed by the arch. */ > + if (xen_hvm_domain() && irq < NR_IRQS_LEGACY) > return; > > irq_free_desc(irq); -- Vitaly