Subject: RE: [PATCH v5 3/8] ACPI/IORT: Add a helper to retrieve RMR memory regions

From: Shameerali Kolothum Thodi <[email-masked]>
Date: Mon, 14 Jun 2021 12:49:22 +0000

> -----Original Message-----
> From: Robin Murphy [mailto:[email-masked]]
> Sent: 14 June 2021 12:23
> To: Shameerali Kolothum Thodi <[email-masked]>;
> [email-masked]; [email-masked];
> [email-masked]
> Cc: [email-masked]; Linuxarm <[email-masked]>;
> [email-masked]; Guohanjun (Hanjun Guo) <[email-masked]>;
> yangyicong <[email-masked]>; [email-masked];
> wanghuiqiang <[email-masked]>
> Subject: Re: [PATCH v5 3/8] ACPI/IORT: Add a helper to retrieve RMR memory
> regions
> 
> On 2021-05-24 12:02, Shameer Kolothum wrote:
> > Add a helper function that retrieves RMR memory descriptors
> > associated with a given IOMMU. This will be used by IOMMU
> > drivers to setup necessary mappings.
> >
> > Now that we have this, invoke it from the generic helper
> > interface.
> >
> > Signed-off-by: Shameer Kolothum
> <[email-masked]>
> > ---
> >   drivers/acpi/arm64/iort.c | 50
> +++++++++++++++++++++++++++++++++++++++
> >   drivers/iommu/dma-iommu.c |  4 ++++
> >   include/linux/acpi_iort.h |  7 ++++++
> >   3 files changed, 61 insertions(+)
> >
> > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > index fea1ffaedf3b..01917caf58de 100644
> > --- a/drivers/acpi/arm64/iort.c
> > +++ b/drivers/acpi/arm64/iort.c
> > @@ -12,6 +12,7 @@
> >
> >   #include <linux/acpi_iort.h>
> >   #include <linux/bitfield.h>
> > +#include <linux/dma-iommu.h>
> >   #include <linux/iommu.h>
> >   #include <linux/kernel.h>
> >   #include <linux/list.h>
> > @@ -837,6 +838,53 @@ static inline int iort_add_device_replay(struct
> device *dev)
> >   	return err;
> >   }
> >
> > +/**
> > + * iort_iommu_get_rmrs - Helper to retrieve RMR info associated with
> IOMMU
> > + * @iommu: fwnode for the IOMMU
> > + * @head: RMR list head to be populated
> > + *
> > + * Returns: 0 on success, <0 failure
> > + */
> > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > +			struct list_head *head)
> > +{
> > +	struct iort_rmr_entry *e;
> > +	struct acpi_iort_node *iommu;
> > +	int rmrs = 0;
> > +
> > +	iommu = iort_get_iort_node(iommu_fwnode);
> > +	if (!iommu || list_empty(&iort_rmr_list))
> > +		return -ENODEV;
> > +
> > +	list_for_each_entry(e, &iort_rmr_list, list) {
> > +		int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_NOEXEC |
> IOMMU_MMIO;
> > +		struct iommu_resv_region *region;
> > +		enum iommu_resv_type type;
> > +		struct acpi_iort_rmr_desc *rmr_desc;
> > +
> > +		if (e->smmu != iommu)
> > +			continue;
> > +
> > +		rmr_desc = e->rmr_desc;
> > +		if (e->flags & IOMMU_RMR_REMAP_PERMITTED)
> > +			type = IOMMU_RESV_DIRECT_RELAXABLE;
> > +		else
> > +			type = IOMMU_RESV_DIRECT;
> 
> Wasn't the idea that we can do all this during the initial parsing, i.e.
> we don't even have iort_rmr_entry, we store them as iommu_resv_regions
> and simply kmemdup() or whatever at this point?

Hmm... Not yet. I removed struct iommu_rmr() from v4. But yes, it looks like
we can get rid of iort_rmr_entry as well. Will give it a go in next.

Thanks,
Shameer

> Robin.
> 
> > +
> > +		region = iommu_alloc_resv_region(rmr_desc->base_address,
> > +						 rmr_desc->length,
> > +						 prot, type);
> > +		if (region) {
> > +			region->fw_data.rmr.flags = e->flags;
> > +			region->fw_data.rmr.sid = e->sid;
> > +			list_add_tail(&region->list, head);
> > +			rmrs++;
> > +		}
> > +	}
> > +
> > +	return (rmrs == 0) ? -ENODEV : 0;
> > +}
> > +
> >   /**
> >    * iort_iommu_msi_get_resv_regions - Reserved region driver helper
> >    * @dev: Device from iommu_get_resv_regions()
> > @@ -1108,6 +1156,8 @@ int iort_iommu_msi_get_resv_regions(struct
> device *dev, struct list_head *head)
> >   const struct iommu_ops *iort_iommu_configure_id(struct device *dev,
> >   						const u32 *input_id)
> >   { return NULL; }
> > +int iort_iommu_get_rmrs(struct fwnode_handle *fwnode, struct list_head
> *head)
> > +{ return -ENODEV; }
> >   #endif
> >
> >   static int nc_dma_get_range(struct device *dev, u64 *size)
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index 229ec65d98be..f893d460cfa4 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -185,6 +185,9 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
> >   int iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode,
> >   		       struct list_head *list)
> >   {
> > +	if (!is_of_node(iommu_fwnode))
> > +		return iort_iommu_get_rmrs(iommu_fwnode, list);
> > +
> >   	return -EINVAL;
> >   }
> >   EXPORT_SYMBOL(iommu_dma_get_rmrs);
> > @@ -200,6 +203,7 @@ EXPORT_SYMBOL(iommu_dma_get_rmrs);
> >   void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
> >   			struct list_head *list)
> >   {
> > +	generic_iommu_put_resv_regions(iommu_fwnode->dev, list);
> >   }
> >   EXPORT_SYMBOL(iommu_dma_put_rmrs);
> >
> > diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> > index 1a12baa58e40..e8c45fa59531 100644
> > --- a/include/linux/acpi_iort.h
> > +++ b/include/linux/acpi_iort.h
> > @@ -39,6 +39,8 @@ const struct iommu_ops
> *iort_iommu_configure_id(struct device *dev,
> >   						const u32 *id_in);
> >   int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head
> *head);
> >   phys_addr_t acpi_iort_dma_get_max_cpu_address(void);
> > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > +			struct list_head *list);
> >   #else
> >   static inline void acpi_iort_init(void) { }
> >   static inline u32 iort_msi_map_id(struct device *dev, u32 id)
> > @@ -59,6 +61,11 @@ int iort_iommu_msi_get_resv_regions(struct device
> *dev, struct list_head *head)
> >
> >   static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)
> >   { return PHYS_ADDR_MAX; }
> > +
> > +static inline
> > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > +			struct list_head *list)
> > +{ return -ENODEV; }
> >   #endif
> >
> >   #endif /* __ACPI_IORT_H__ */
> >
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