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Date: Thu, 11 Jun 2015 20:22:44 +0100 From: Robin Murphy <robin.murphy@....com> To: Joerg Roedel <joro@...tes.org>, "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org> CC: Will Deacon <Will.Deacon@....com>, Kukjin Kim <kgene@...nel.org>, David Woodhouse <dwmw2@...radead.org>, Heiko Stuebner <heiko@...ech.de>, Hiroshi Doyu <hdoyu@...dia.com>, Thierry Reding <thierry.reding@...il.com>, Alex Williamson <alex.williamson@...hat.com>, Laurent Pinchart <laurent.pinchart@...asonboard.com>, Oded Gabbay <oded.gabbay@...il.com>, "jroedel@...e.de" <jroedel@...e.de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 10/22] iommu: Introduce direct mapped region handling On 28/05/15 17:41, Joerg Roedel wrote: > From: Joerg Roedel <jroedel@...e.de> > > Add two new functions to the IOMMU-API to allow the IOMMU > drivers to export the requirements for direct mapped regions > per device. > This is useful for exporting the information in Intel VT-d's > RMRR entries or AMD-Vi's unity mappings. Whilst I agree with the utility of a common abstraction for the IOMMU core to use (I think we could easily turn Marek's proposal for ARM[1] into a generic of_iommu_ backend for this), I'm less convinced that it needs to be exported as part of the API. I was envisioning eventually moving the IOVA data inside the iommu_domain itself for the managed DMA-API implementation, so that the IOMMU core would be responsible for setting it up. Then the core just needs to ask the driver about any relevant reservations as it creates a domain/attaches a device, and the callers can remain in blissful ignorance. Besides, beyond probe time, I don't see many good reasons at all for a caller to have a struct device for something, yet not have taken control of any DMA the firmware left running. Is that at odds with your ideas? Robin. [1]:http://article.gmane.org/gmane.linux.kernel.samsung-soc/45429 > Signed-off-by: Joerg Roedel <jroedel@...e.de> > --- > drivers/iommu/iommu.c | 16 ++++++++++++++++ > include/linux/iommu.h | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 47 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index a0a38bd..6b8d6e7 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -1469,3 +1469,19 @@ int iommu_domain_set_attr(struct iommu_domain *domain, > return ret; > } > EXPORT_SYMBOL_GPL(iommu_domain_set_attr); > + > +void iommu_get_dm_regions(struct device *dev, struct list_head *list) > +{ > + const struct iommu_ops *ops = dev->bus->iommu_ops; > + > + if (ops && ops->get_dm_regions) > + ops->get_dm_regions(dev, list); > +} > + > +void iommu_put_dm_regions(struct device *dev, struct list_head *list) > +{ > + const struct iommu_ops *ops = dev->bus->iommu_ops; > + > + if (ops && ops->put_dm_regions) > + ops->put_dm_regions(dev, list); > +} > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 683a1c4..6894999 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -114,6 +114,20 @@ enum iommu_attr { > DOMAIN_ATTR_MAX, > }; > > +/** > + * struct iommu_dm_region - descriptor for a direct mapped memory region > + * @list: Linked list pointers > + * @start: System physical start address of the region > + * @length: Length of the region in bytes > + * @prot: IOMMU Protection flags (READ/WRITE/...) > + */ > +struct iommu_dm_region { > + struct list_head list; > + phys_addr_t start; > + size_t length; > + int prot; > +}; > + > #ifdef CONFIG_IOMMU_API > > /** > @@ -159,6 +173,10 @@ struct iommu_ops { > int (*domain_set_attr)(struct iommu_domain *domain, > enum iommu_attr attr, void *data); > > + /* Request/Free a list of direct mapping requirements for a device */ > + void (*get_dm_regions)(struct device *dev, struct list_head *list); > + void (*put_dm_regions)(struct device *dev, struct list_head *list); > + > /* Window handling functions */ > int (*domain_window_enable)(struct iommu_domain *domain, u32 wnd_nr, > phys_addr_t paddr, u64 size, int prot); > @@ -205,6 +223,9 @@ extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t io > extern void iommu_set_fault_handler(struct iommu_domain *domain, > iommu_fault_handler_t handler, void *token); > > +extern void iommu_get_dm_regions(struct device *dev, struct list_head *list); > +extern void iommu_put_dm_regions(struct device *dev, struct list_head *list); > + > extern int iommu_attach_group(struct iommu_domain *domain, > struct iommu_group *group); > extern void iommu_detach_group(struct iommu_domain *domain, > @@ -379,6 +400,16 @@ static inline void iommu_set_fault_handler(struct iommu_domain *domain, > { > } > > +static inline void iommu_get_dm_regions(struct device *dev, > + struct list_head *list) > +{ > +} > + > +static inline void iommu_put_dm_regions(struct device *dev, > + struct list_head *list) > +{ > +} > + > static inline int iommu_attach_group(struct iommu_domain *domain, > struct iommu_group *group) > { > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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