From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [v7 4/8] iommu, x86: No need to migrating irq for VT-d Posted-Interrupts Date: Mon, 25 May 2015 10:38:21 +0200 (CEST) Message-ID: References: <1432531734-25978-1-git-send-email-feng.wu@intel.com> <1432531734-25978-5-git-send-email-feng.wu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1432531734-25978-5-git-send-email-feng.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Feng Wu Cc: dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Mon, 25 May 2015, Feng Wu wrote: > We don't need to migrate the irqs for VT-d Posted-Interrupts here. > When 'pst' is set in IRTE, the associated irq will be posted to > guests instead of interrupt remapping. The destination of the > interrupt is set in Posted-Interrupts Descriptor, and the migration > happens during vCPU scheduling. > > However, we still update the cached irte here, which can be used > when changing back to remapping mode. > > Signed-off-by: Feng Wu > Reviewed-by: Jiang Liu > Acked-by: David Woodhouse > --- > drivers/iommu/intel_irq_remapping.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c > index 1955b09..646f4cf 100644 > --- a/drivers/iommu/intel_irq_remapping.c > +++ b/drivers/iommu/intel_irq_remapping.c > @@ -994,7 +994,10 @@ intel_ir_set_affinity(struct irq_data *data, const struct cpumask *mask, > */ > irte->vector = cfg->vector; > irte->dest_id = IRTE_DEST(cfg->dest_apicid); > - modify_irte(&ir_data->irq_2_iommu, irte); > + > + /* We don't need to modify irte if the interrupt is for posting. */ > + if (irte->pst != 1) > + modify_irte(&ir_data->irq_2_iommu, irte); I don't think this is correct. ir_data->irte_entry contains the non posted version, which has pst == 0. You need some other way to store whether you are in posted mode or not. Thanks, tglx