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[PATCH v5 16/16] of: Add plumbing for restricted DMA pool

Claire Chang posted 16 patches 4 years, 9 months ago
There is a newer version of this series
[PATCH v5 16/16] of: Add plumbing for restricted DMA pool
Posted by Claire Chang 4 years, 9 months ago 
If a device is not behind an IOMMU, we look up the device node and set
up the restricted DMA when the restricted-dma-pool is presented.

Signed-off-by: Claire Chang <tientzu@chromium.org>
---
 drivers/of/address.c    | 25 +++++++++++++++++++++++++
 drivers/of/device.c     |  3 +++
 drivers/of/of_private.h |  5 +++++
 3 files changed, 33 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 54f221dde267..fff3adfe4986 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -8,6 +8,7 @@
 #include <linux/logic_pio.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/sizes.h>
@@ -1109,6 +1110,30 @@ bool of_dma_is_coherent(struct device_node *np)
 }
 EXPORT_SYMBOL_GPL(of_dma_is_coherent);
 
+int of_dma_set_restricted_buffer(struct device *dev)
+{
+	struct device_node *node;
+	int count, i;
+
+	if (!dev->of_node)
+		return 0;
+
+	count = of_property_count_elems_of_size(dev->of_node, "memory-region",
+						sizeof(phandle));
+	for (i = 0; i < count; i++) {
+		node = of_parse_phandle(dev->of_node, "memory-region", i);
+		/* There might be multiple memory regions, but only one
+		 * restriced-dma-pool region is allowed.
+		 */
+		if (of_device_is_compatible(node, "restricted-dma-pool") &&
+		    of_device_is_available(node))
+			return of_reserved_mem_device_init_by_idx(
+				dev, dev->of_node, i);
+	}
+
+	return 0;
+}
+
 /**
  * of_mmio_is_nonposted - Check if device uses non-posted MMIO
  * @np:	device node
diff --git a/drivers/of/device.c b/drivers/of/device.c
index c5a9473a5fb1..d8d865223e51 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -165,6 +165,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
 
 	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
 
+	if (!iommu)
+		return of_dma_set_restricted_buffer(dev);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_dma_configure_id);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index d717efbd637d..e9237f5eff48 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -163,12 +163,17 @@ struct bus_dma_region;
 #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
 int of_dma_get_range(struct device_node *np,
 		const struct bus_dma_region **map);
+int of_dma_set_restricted_buffer(struct device *dev);
 #else
 static inline int of_dma_get_range(struct device_node *np,
 		const struct bus_dma_region **map)
 {
 	return -ENODEV;
 }
+static inline int of_dma_get_restricted_buffer(struct device *dev)
+{
+	return -ENODEV;
+}
 #endif
 
 #endif /* _LINUX_OF_PRIVATE_H */
-- 
2.31.1.368.gbe11c130af-goog
Re: [PATCH v5 16/16] of: Add plumbing for restricted DMA pool
Posted by Claire Chang 4 years, 9 months ago 
On Thu, Apr 22, 2021 at 4:17 PM Claire Chang <tientzu@chromium.org> wrote:
>
> If a device is not behind an IOMMU, we look up the device node and set
> up the restricted DMA when the restricted-dma-pool is presented.
>
> Signed-off-by: Claire Chang <tientzu@chromium.org>
> ---
>  drivers/of/address.c    | 25 +++++++++++++++++++++++++
>  drivers/of/device.c     |  3 +++
>  drivers/of/of_private.h |  5 +++++
>  3 files changed, 33 insertions(+)
>
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 54f221dde267..fff3adfe4986 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -8,6 +8,7 @@
>  #include <linux/logic_pio.h>
>  #include <linux/module.h>
>  #include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/pci.h>
>  #include <linux/pci_regs.h>
>  #include <linux/sizes.h>
> @@ -1109,6 +1110,30 @@ bool of_dma_is_coherent(struct device_node *np)
>  }
>  EXPORT_SYMBOL_GPL(of_dma_is_coherent);
>
> +int of_dma_set_restricted_buffer(struct device *dev)
> +{
> +       struct device_node *node;
> +       int count, i;
> +
> +       if (!dev->of_node)
> +               return 0;
> +
> +       count = of_property_count_elems_of_size(dev->of_node, "memory-region",
> +                                               sizeof(phandle));
> +       for (i = 0; i < count; i++) {
> +               node = of_parse_phandle(dev->of_node, "memory-region", i);
> +               /* There might be multiple memory regions, but only one
> +                * restriced-dma-pool region is allowed.
> +                */
> +               if (of_device_is_compatible(node, "restricted-dma-pool") &&
> +                   of_device_is_available(node))
> +                       return of_reserved_mem_device_init_by_idx(
> +                               dev, dev->of_node, i);
> +       }
> +
> +       return 0;
> +}
> +
>  /**
>   * of_mmio_is_nonposted - Check if device uses non-posted MMIO
>   * @np:        device node
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index c5a9473a5fb1..d8d865223e51 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -165,6 +165,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>
>         arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
>
> +       if (!iommu)
> +               return of_dma_set_restricted_buffer(dev);
> +
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(of_dma_configure_id);
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index d717efbd637d..e9237f5eff48 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -163,12 +163,17 @@ struct bus_dma_region;
>  #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
>  int of_dma_get_range(struct device_node *np,
>                 const struct bus_dma_region **map);
> +int of_dma_set_restricted_buffer(struct device *dev);
>  #else
>  static inline int of_dma_get_range(struct device_node *np,
>                 const struct bus_dma_region **map)
>  {
>         return -ENODEV;
>  }
> +static inline int of_dma_get_restricted_buffer(struct device *dev)

This one should be of_dma_set_restricted_buffer. Sorry for the typo.

> +{
> +       return -ENODEV;
> +}
>  #endif
>
>  #endif /* _LINUX_OF_PRIVATE_H */
> --
> 2.31.1.368.gbe11c130af-goog
>
Re: [PATCH v5 16/16] of: Add plumbing for restricted DMA pool
Posted by Robin Murphy 4 years, 9 months ago 
On 2021-04-22 09:15, Claire Chang wrote:
> If a device is not behind an IOMMU, we look up the device node and set
> up the restricted DMA when the restricted-dma-pool is presented.
> 
> Signed-off-by: Claire Chang <tientzu@chromium.org>
> ---
>   drivers/of/address.c    | 25 +++++++++++++++++++++++++
>   drivers/of/device.c     |  3 +++
>   drivers/of/of_private.h |  5 +++++
>   3 files changed, 33 insertions(+)
> 
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 54f221dde267..fff3adfe4986 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -8,6 +8,7 @@
>   #include <linux/logic_pio.h>
>   #include <linux/module.h>
>   #include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>   #include <linux/pci.h>
>   #include <linux/pci_regs.h>
>   #include <linux/sizes.h>
> @@ -1109,6 +1110,30 @@ bool of_dma_is_coherent(struct device_node *np)
>   }
>   EXPORT_SYMBOL_GPL(of_dma_is_coherent);
>   
> +int of_dma_set_restricted_buffer(struct device *dev)
> +{
> +	struct device_node *node;
> +	int count, i;
> +
> +	if (!dev->of_node)
> +		return 0;
> +
> +	count = of_property_count_elems_of_size(dev->of_node, "memory-region",
> +						sizeof(phandle));
> +	for (i = 0; i < count; i++) {
> +		node = of_parse_phandle(dev->of_node, "memory-region", i);
> +		/* There might be multiple memory regions, but only one
> +		 * restriced-dma-pool region is allowed.
> +		 */

What's the use-case for having multiple regions if the restricted pool 
is by definition the only one accessible?

Robin.

> +		if (of_device_is_compatible(node, "restricted-dma-pool") &&
> +		    of_device_is_available(node))
> +			return of_reserved_mem_device_init_by_idx(
> +				dev, dev->of_node, i);
> +	}
> +
> +	return 0;
> +}
> +
>   /**
>    * of_mmio_is_nonposted - Check if device uses non-posted MMIO
>    * @np:	device node
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index c5a9473a5fb1..d8d865223e51 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -165,6 +165,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>   
>   	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
>   
> +	if (!iommu)
> +		return of_dma_set_restricted_buffer(dev);
> +
>   	return 0;
>   }
>   EXPORT_SYMBOL_GPL(of_dma_configure_id);
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index d717efbd637d..e9237f5eff48 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -163,12 +163,17 @@ struct bus_dma_region;
>   #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
>   int of_dma_get_range(struct device_node *np,
>   		const struct bus_dma_region **map);
> +int of_dma_set_restricted_buffer(struct device *dev);
>   #else
>   static inline int of_dma_get_range(struct device_node *np,
>   		const struct bus_dma_region **map)
>   {
>   	return -ENODEV;
>   }
> +static inline int of_dma_get_restricted_buffer(struct device *dev)
> +{
> +	return -ENODEV;
> +}
>   #endif
>   
>   #endif /* _LINUX_OF_PRIVATE_H */
>
Re: [PATCH v5 16/16] of: Add plumbing for restricted DMA pool
Posted by Claire Chang 4 years, 9 months ago 
On Fri, Apr 23, 2021 at 9:35 PM Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2021-04-22 09:15, Claire Chang wrote:
> > If a device is not behind an IOMMU, we look up the device node and set
> > up the restricted DMA when the restricted-dma-pool is presented.
> >
> > Signed-off-by: Claire Chang <tientzu@chromium.org>
> > ---
> >   drivers/of/address.c    | 25 +++++++++++++++++++++++++
> >   drivers/of/device.c     |  3 +++
> >   drivers/of/of_private.h |  5 +++++
> >   3 files changed, 33 insertions(+)
> >
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 54f221dde267..fff3adfe4986 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -8,6 +8,7 @@
> >   #include <linux/logic_pio.h>
> >   #include <linux/module.h>
> >   #include <linux/of_address.h>
> > +#include <linux/of_reserved_mem.h>
> >   #include <linux/pci.h>
> >   #include <linux/pci_regs.h>
> >   #include <linux/sizes.h>
> > @@ -1109,6 +1110,30 @@ bool of_dma_is_coherent(struct device_node *np)
> >   }
> >   EXPORT_SYMBOL_GPL(of_dma_is_coherent);
> >
> > +int of_dma_set_restricted_buffer(struct device *dev)
> > +{
> > +     struct device_node *node;
> > +     int count, i;
> > +
> > +     if (!dev->of_node)
> > +             return 0;
> > +
> > +     count = of_property_count_elems_of_size(dev->of_node, "memory-region",
> > +                                             sizeof(phandle));
> > +     for (i = 0; i < count; i++) {
> > +             node = of_parse_phandle(dev->of_node, "memory-region", i);
> > +             /* There might be multiple memory regions, but only one
> > +              * restriced-dma-pool region is allowed.
> > +              */
>
> What's the use-case for having multiple regions if the restricted pool
> is by definition the only one accessible?

There might be a device coherent pool (shared-dma-pool) and
dma_alloc_attrs might allocate memory from that pool [1].
I'm not sure if it makes sense to have another device coherent pool
while using restricted DMA pool though.

[1] https://elixir.bootlin.com/linux/v5.12/source/kernel/dma/mapping.c#L435


>
> Robin.
>
> > +             if (of_device_is_compatible(node, "restricted-dma-pool") &&
> > +                 of_device_is_available(node))
> > +                     return of_reserved_mem_device_init_by_idx(
> > +                             dev, dev->of_node, i);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> >   /**
> >    * of_mmio_is_nonposted - Check if device uses non-posted MMIO
> >    * @np:     device node
> > diff --git a/drivers/of/device.c b/drivers/of/device.c
> > index c5a9473a5fb1..d8d865223e51 100644
> > --- a/drivers/of/device.c
> > +++ b/drivers/of/device.c
> > @@ -165,6 +165,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
> >
> >       arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
> >
> > +     if (!iommu)
> > +             return of_dma_set_restricted_buffer(dev);
> > +
> >       return 0;
> >   }
> >   EXPORT_SYMBOL_GPL(of_dma_configure_id);
> > diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> > index d717efbd637d..e9237f5eff48 100644
> > --- a/drivers/of/of_private.h
> > +++ b/drivers/of/of_private.h
> > @@ -163,12 +163,17 @@ struct bus_dma_region;
> >   #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
> >   int of_dma_get_range(struct device_node *np,
> >               const struct bus_dma_region **map);
> > +int of_dma_set_restricted_buffer(struct device *dev);
> >   #else
> >   static inline int of_dma_get_range(struct device_node *np,
> >               const struct bus_dma_region **map)
> >   {
> >       return -ENODEV;
> >   }
> > +static inline int of_dma_get_restricted_buffer(struct device *dev)
> > +{
> > +     return -ENODEV;
> > +}
> >   #endif
> >
> >   #endif /* _LINUX_OF_PRIVATE_H */
> >

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