From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v3 5/9] iommu/of: Handle iommu-map property for PCI Date: Fri, 1 Jul 2016 11:31:06 +0100 Message-ID: <20160701103105.GE12735@arm.com> References: <17617dff6e7998b91d53ed8a1d6283b1c7bc3470.1467123945.git.robin.murphy@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <17617dff6e7998b91d53ed8a1d6283b1c7bc3470.1467123945.git.robin.murphy-5wv7dgnIgG8@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: Robin Murphy Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Tue, Jun 28, 2016 at 04:48:24PM +0100, Robin Murphy wrote: > Now that we have a way to pick up the RID translation and target IOMMU, > hook up of_iommu_configure() to bring PCI devices into the of_xlate > mechanism and allow them IOMMU-backed DMA ops without the need for > driver-specific handling. > > Signed-off-by: Robin Murphy > --- > > v3: Use explicit "iommu-map-mask", drop of_device_is_available() check. > > drivers/iommu/of_iommu.c | 43 ++++++++++++++++++++++++++++++++++++------- > 1 file changed, 36 insertions(+), 7 deletions(-) > > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c > index 7e6369cffc95..25406a8b9d4e 100644 > --- a/drivers/iommu/of_iommu.c > +++ b/drivers/iommu/of_iommu.c > @@ -22,6 +22,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -138,20 +139,48 @@ const struct iommu_ops *of_iommu_get_ops(struct device_node *np) > return ops; > } > > +static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data) > +{ > + struct of_phandle_args *iommu_spec = data; > + > + iommu_spec->args[0] = alias; > + return iommu_spec->np == pdev->bus->dev.of_node; > +} > + > const struct iommu_ops *of_iommu_configure(struct device *dev, > struct device_node *master_np) > { > struct of_phandle_args iommu_spec; > - struct device_node *np; > + struct device_node *np = NULL; This sets off some alarm bells... > const struct iommu_ops *ops = NULL; > int idx = 0; > > - /* > - * We can't do much for PCI devices without knowing how > - * device IDs are wired up from the PCI bus to the IOMMU. > - */ > - if (dev_is_pci(dev)) > - return NULL; > + if (dev_is_pci(dev)) { > + /* > + * Start by tracing the RID alias down the PCI topology as > + * far as the host bridge whose OF node we have... > + */ > + iommu_spec.np = master_np; > + pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid, > + &iommu_spec); > + /* > + * ...then find out what that becomes once it escapes the PCI > + * bus into the system beyond, and which IOMMU it ends up at. > + */ > + if (of_pci_map_rid(master_np, iommu_spec.args[0], "iommu-map", > + "iommu-map-mask", &np, iommu_spec.args)) > + return NULL; ... because you're assumedly initialising np to NULL in case of_pci_map_rid returns 0, but doesn't set np... > + > + /* We're not attempting to handle multi-alias devices yet */ > + iommu_spec.np = np; > + iommu_spec.args_count = 1; > + ops = of_iommu_get_ops(np); ... and then we call of_iommu_get_ops(NULL). Does that make any sense? Will