[PATCH v4 0/1] Add iommu map_sg/unmap_sg API

[PATCH v4 0/1] Add iommu map_sg/unmap_sg API

[Olav Haugan]

Patch for adding map_sg/unmap_sg to the generic IOMMU API.

v3 -> v4:
* Removed BUG_ON in both map_sg and unmap_sg
* Removed PAGE_ALIGN of length of mapping

v2 -> v3:
* Updated commit text
* Simplifed fallback code and fixed variable types in map_sg function.
* Renamed and changed arguments to map and unmap functions

v1 -> v2:
* Added support for "option" argument to unmap call. This can be used by
  IOMMU driver implentations to allow clients to signal to the driver not
  to do TLB invalidate for example.
* Added fallback in case iommu_{map,unmap}_range is called for an IOMMU driver
  that does not have these implemented.
* Rebased on top of Joerg's tree.
* Split out patch from the rest of the patches.



Olav Haugan (1):
  iommu-api: Add map_sg/unmap_sg functions

 drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 0/1] Add iommu map_sg/unmap_sg API

[Olav Haugan]

Patch for adding map_sg/unmap_sg to the generic IOMMU API.

v3 -> v4:
* Removed BUG_ON in both map_sg and unmap_sg
* Removed PAGE_ALIGN of length of mapping

v2 -> v3:
* Updated commit text
* Simplifed fallback code and fixed variable types in map_sg function.
* Renamed and changed arguments to map and unmap functions

v1 -> v2:
* Added support for "option" argument to unmap call. This can be used by
  IOMMU driver implentations to allow clients to signal to the driver not
  to do TLB invalidate for example.
* Added fallback in case iommu_{map,unmap}_range is called for an IOMMU driver
  that does not have these implemented.
* Rebased on top of Joerg's tree.
* Split out patch from the rest of the patches.



Olav Haugan (1):
  iommu-api: Add map_sg/unmap_sg functions

 drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Mapping and unmapping are more often than not in the critical path.
map_sg and unmap_sg allows IOMMU driver implementations to optimize
the process of mapping and unmapping buffers into the IOMMU page tables.

Instead of mapping a buffer one page at a time and requiring potentially
expensive TLB operations for each page, this function allows the driver
to map all pages in one go and defer TLB maintenance until after all
pages have been mapped.

Additionally, the mapping operation would be faster in general since
clients does not have to keep calling map API over and over again for
each physically contiguous chunk of memory that needs to be mapped to a
virtually contiguous region.

Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
---
 drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1698360..1d5dc2e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
 }
 EXPORT_SYMBOL_GPL(iommu_unmap);
 
+int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents,
+			int prot, unsigned long flags)
+{
+	int ret = 0;
+	unsigned long offset = 0;
+
+	if (unlikely(domain->ops->map_sg == NULL)) {
+		unsigned int i;
+		struct scatterlist *s;
+
+		for_each_sg(sg, s, nents, i) {
+			phys_addr_t phys = page_to_phys(sg_page(s));
+			size_t page_len = s->offset + s->length;
+
+			ret = iommu_map(domain, iova + offset, phys, page_len,
+					prot);
+			if (ret)
+				goto fail;
+
+			offset += page_len;
+		}
+	} else {
+		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
+	}
+	goto out;
+
+fail:
+	/* undo mappings already done in case of error */
+	iommu_unmap(domain, iova, offset);
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_map_sg);
+
+int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
+			size_t size, unsigned long flags)
+{
+	if (unlikely(domain->ops->unmap_sg == NULL))
+		return iommu_unmap(domain, iova, size);
+	else
+		return domain->ops->unmap_sg(domain, iova, size, flags);
+}
+EXPORT_SYMBOL_GPL(iommu_unmap_sg);
 
 int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
 			       phys_addr_t paddr, u64 size, int prot)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 20f9a52..66ad543 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -22,6 +22,7 @@
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/types.h>
+#include <linux/scatterlist.h>
 #include <trace/events/iommu.h>
 
 #define IOMMU_READ	(1 << 0)
@@ -93,6 +94,10 @@ enum iommu_attr {
  * @detach_dev: detach device from an iommu domain
  * @map: map a physically contiguous memory region to an iommu domain
  * @unmap: unmap a physically contiguous memory region from an iommu domain
+ * @map_sg: map a scatter-gather list of physically contiguous memory chunks
+ * to an iommu domain
+ * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
+ * chunks from an iommu domain
  * @iova_to_phys: translate iova to physical address
  * @domain_has_cap: domain capabilities query
  * @add_device: add device to iommu grouping
@@ -110,6 +115,11 @@ struct iommu_ops {
 		   phys_addr_t paddr, size_t size, int prot);
 	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
 		     size_t size);
+	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags);
+	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
+			size_t size, unsigned long flags);
 	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
 	int (*domain_has_cap)(struct iommu_domain *domain,
 			      unsigned long cap);
@@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		     phys_addr_t paddr, size_t size, int prot);
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 		       size_t size);
+extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags);
+extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
+				size_t size, unsigned long flags);
 extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
 extern int iommu_domain_has_cap(struct iommu_domain *domain,
 				unsigned long cap);
@@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 	return -ENODEV;
 }
 
+static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags)
+{
+	return -ENODEV;
+}
+
+static inline int iommu_unmap_sg(struct iommu_domain *domain,
+			unsigned long iova, size_t size, unsigned long flags)
+{
+	return -ENODEV;
+}
+
 static inline int iommu_domain_window_enable(struct iommu_domain *domain,
 					     u32 wnd_nr, phys_addr_t paddr,
 					     u64 size, int prot)
-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Mapping and unmapping are more often than not in the critical path.
map_sg and unmap_sg allows IOMMU driver implementations to optimize
the process of mapping and unmapping buffers into the IOMMU page tables.

Instead of mapping a buffer one page at a time and requiring potentially
expensive TLB operations for each page, this function allows the driver
to map all pages in one go and defer TLB maintenance until after all
pages have been mapped.

Additionally, the mapping operation would be faster in general since
clients does not have to keep calling map API over and over again for
each physically contiguous chunk of memory that needs to be mapped to a
virtually contiguous region.

Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
---
 drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 1698360..1d5dc2e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
 }
 EXPORT_SYMBOL_GPL(iommu_unmap);
 
+int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents,
+			int prot, unsigned long flags)
+{
+	int ret = 0;
+	unsigned long offset = 0;
+
+	if (unlikely(domain->ops->map_sg == NULL)) {
+		unsigned int i;
+		struct scatterlist *s;
+
+		for_each_sg(sg, s, nents, i) {
+			phys_addr_t phys = page_to_phys(sg_page(s));
+			size_t page_len = s->offset + s->length;
+
+			ret = iommu_map(domain, iova + offset, phys, page_len,
+					prot);
+			if (ret)
+				goto fail;
+
+			offset += page_len;
+		}
+	} else {
+		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
+	}
+	goto out;
+
+fail:
+	/* undo mappings already done in case of error */
+	iommu_unmap(domain, iova, offset);
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_map_sg);
+
+int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
+			size_t size, unsigned long flags)
+{
+	if (unlikely(domain->ops->unmap_sg == NULL))
+		return iommu_unmap(domain, iova, size);
+	else
+		return domain->ops->unmap_sg(domain, iova, size, flags);
+}
+EXPORT_SYMBOL_GPL(iommu_unmap_sg);
 
 int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
 			       phys_addr_t paddr, u64 size, int prot)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 20f9a52..66ad543 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -22,6 +22,7 @@
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/types.h>
+#include <linux/scatterlist.h>
 #include <trace/events/iommu.h>
 
 #define IOMMU_READ	(1 << 0)
@@ -93,6 +94,10 @@ enum iommu_attr {
  * @detach_dev: detach device from an iommu domain
  * @map: map a physically contiguous memory region to an iommu domain
  * @unmap: unmap a physically contiguous memory region from an iommu domain
+ * @map_sg: map a scatter-gather list of physically contiguous memory chunks
+ * to an iommu domain
+ * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
+ * chunks from an iommu domain
  * @iova_to_phys: translate iova to physical address
  * @domain_has_cap: domain capabilities query
  * @add_device: add device to iommu grouping
@@ -110,6 +115,11 @@ struct iommu_ops {
 		   phys_addr_t paddr, size_t size, int prot);
 	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
 		     size_t size);
+	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags);
+	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
+			size_t size, unsigned long flags);
 	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
 	int (*domain_has_cap)(struct iommu_domain *domain,
 			      unsigned long cap);
@@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		     phys_addr_t paddr, size_t size, int prot);
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 		       size_t size);
+extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags);
+extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
+				size_t size, unsigned long flags);
 extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
 extern int iommu_domain_has_cap(struct iommu_domain *domain,
 				unsigned long cap);
@@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 	return -ENODEV;
 }
 
+static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
+			struct scatterlist *sg, unsigned int nents, int prot,
+			unsigned long flags)
+{
+	return -ENODEV;
+}
+
+static inline int iommu_unmap_sg(struct iommu_domain *domain,
+			unsigned long iova, size_t size, unsigned long flags)
+{
+	return -ENODEV;
+}
+
 static inline int iommu_domain_window_enable(struct iommu_domain *domain,
 					     u32 wnd_nr, phys_addr_t paddr,
 					     u64 size, int prot)
-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Will Deacon]

Hi Olav,

On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
> Mapping and unmapping are more often than not in the critical path.
> map_sg and unmap_sg allows IOMMU driver implementations to optimize
> the process of mapping and unmapping buffers into the IOMMU page tables.
> 
> Instead of mapping a buffer one page at a time and requiring potentially
> expensive TLB operations for each page, this function allows the driver
> to map all pages in one go and defer TLB maintenance until after all
> pages have been mapped.
> 
> Additionally, the mapping operation would be faster in general since
> clients does not have to keep calling map API over and over again for
> each physically contiguous chunk of memory that needs to be mapped to a
> virtually contiguous region.

Just a couple of minor comments, but I think this is almost there now.

> Signed-off-by: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1698360..1d5dc2e 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>  }
>  EXPORT_SYMBOL_GPL(iommu_unmap);
>  
> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents,
> +			int prot, unsigned long flags)
> +{

What do you anticipate passing in the flags parameter? I assume it's
something specific to the scatterlist, since we can't provide this to
iommu_map as it stands?

> +	int ret = 0;
> +	unsigned long offset = 0;
> +
> +	if (unlikely(domain->ops->map_sg == NULL)) {
> +		unsigned int i;
> +		struct scatterlist *s;
> +
> +		for_each_sg(sg, s, nents, i) {
> +			phys_addr_t phys = page_to_phys(sg_page(s));
> +			size_t page_len = s->offset + s->length;
> +
> +			ret = iommu_map(domain, iova + offset, phys, page_len,
> +					prot);
> +			if (ret)
> +				goto fail;
> +
> +			offset += page_len;
> +		}
> +	} else {
> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
> +	}
> +	goto out;
> +
> +fail:
> +	/* undo mappings already done in case of error */
> +	iommu_unmap(domain, iova, offset);

I think this would be cleaner if you stuck it in the loop above and removed
all these labels:

  if (ret) {
	iommu_unmap(...);
	break;
  }

Will

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Will Deacon]

Hi Olav,

On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
> Mapping and unmapping are more often than not in the critical path.
> map_sg and unmap_sg allows IOMMU driver implementations to optimize
> the process of mapping and unmapping buffers into the IOMMU page tables.
> 
> Instead of mapping a buffer one page at a time and requiring potentially
> expensive TLB operations for each page, this function allows the driver
> to map all pages in one go and defer TLB maintenance until after all
> pages have been mapped.
> 
> Additionally, the mapping operation would be faster in general since
> clients does not have to keep calling map API over and over again for
> each physically contiguous chunk of memory that needs to be mapped to a
> virtually contiguous region.

Just a couple of minor comments, but I think this is almost there now.

> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
> ---
>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1698360..1d5dc2e 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>  }
>  EXPORT_SYMBOL_GPL(iommu_unmap);
>  
> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents,
> +			int prot, unsigned long flags)
> +{

What do you anticipate passing in the flags parameter? I assume it's
something specific to the scatterlist, since we can't provide this to
iommu_map as it stands?

> +	int ret = 0;
> +	unsigned long offset = 0;
> +
> +	if (unlikely(domain->ops->map_sg == NULL)) {
> +		unsigned int i;
> +		struct scatterlist *s;
> +
> +		for_each_sg(sg, s, nents, i) {
> +			phys_addr_t phys = page_to_phys(sg_page(s));
> +			size_t page_len = s->offset + s->length;
> +
> +			ret = iommu_map(domain, iova + offset, phys, page_len,
> +					prot);
> +			if (ret)
> +				goto fail;
> +
> +			offset += page_len;
> +		}
> +	} else {
> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
> +	}
> +	goto out;
> +
> +fail:
> +	/* undo mappings already done in case of error */
> +	iommu_unmap(domain, iova, offset);

I think this would be cleaner if you stuck it in the loop above and removed
all these labels:

  if (ret) {
	iommu_unmap(...);
	break;
  }

Will

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Hi Will,

On 8/1/2014 1:22 AM, Will Deacon wrote:
> Hi Olav,
> 
> On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
>> Mapping and unmapping are more often than not in the critical path.
>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>
>> Instead of mapping a buffer one page at a time and requiring potentially
>> expensive TLB operations for each page, this function allows the driver
>> to map all pages in one go and defer TLB maintenance until after all
>> pages have been mapped.
>>
>> Additionally, the mapping operation would be faster in general since
>> clients does not have to keep calling map API over and over again for
>> each physically contiguous chunk of memory that needs to be mapped to a
>> virtually contiguous region.
> 
> Just a couple of minor comments, but I think this is almost there now.
> 
>> Signed-off-by: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
>> ---
>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>  2 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1698360..1d5dc2e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>  
>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents,
>> +			int prot, unsigned long flags)
>> +{
> 
> What do you anticipate passing in the flags parameter? I assume it's
> something specific to the scatterlist, since we can't provide this to
> iommu_map as it stands?

Initially the flags argument is planned to be used by clients to
indicate to the driver that no TLB operation is necessary. This allows
clients to for example map/unmap multiple scatter-gather lists without
doing expensive TLB invalidate operations for each call but just do this
at the last mapping/unmapping call instead. I believe Rob Clark was
looking for this feature and I can see the benefit for our use cases also.

>> +	int ret = 0;
>> +	unsigned long offset = 0;
>> +
>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>> +		unsigned int i;
>> +		struct scatterlist *s;
>> +
>> +		for_each_sg(sg, s, nents, i) {
>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>> +			size_t page_len = s->offset + s->length;
>> +
>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>> +					prot);
>> +			if (ret)
>> +				goto fail;
>> +
>> +			offset += page_len;
>> +		}
>> +	} else {
>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>> +	}
>> +	goto out;
>> +
>> +fail:
>> +	/* undo mappings already done in case of error */
>> +	iommu_unmap(domain, iova, offset);
> 
> I think this would be cleaner if you stuck it in the loop above and removed
> all these labels:
> 
>   if (ret) {
> 	iommu_unmap(...);
> 	break;
>   }

Sure, I can do that.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Hi Will,

On 8/1/2014 1:22 AM, Will Deacon wrote:
> Hi Olav,
> 
> On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
>> Mapping and unmapping are more often than not in the critical path.
>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>
>> Instead of mapping a buffer one page at a time and requiring potentially
>> expensive TLB operations for each page, this function allows the driver
>> to map all pages in one go and defer TLB maintenance until after all
>> pages have been mapped.
>>
>> Additionally, the mapping operation would be faster in general since
>> clients does not have to keep calling map API over and over again for
>> each physically contiguous chunk of memory that needs to be mapped to a
>> virtually contiguous region.
> 
> Just a couple of minor comments, but I think this is almost there now.
> 
>> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
>> ---
>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>  2 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1698360..1d5dc2e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>  
>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents,
>> +			int prot, unsigned long flags)
>> +{
> 
> What do you anticipate passing in the flags parameter? I assume it's
> something specific to the scatterlist, since we can't provide this to
> iommu_map as it stands?

Initially the flags argument is planned to be used by clients to
indicate to the driver that no TLB operation is necessary. This allows
clients to for example map/unmap multiple scatter-gather lists without
doing expensive TLB invalidate operations for each call but just do this
at the last mapping/unmapping call instead. I believe Rob Clark was
looking for this feature and I can see the benefit for our use cases also.

>> +	int ret = 0;
>> +	unsigned long offset = 0;
>> +
>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>> +		unsigned int i;
>> +		struct scatterlist *s;
>> +
>> +		for_each_sg(sg, s, nents, i) {
>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>> +			size_t page_len = s->offset + s->length;
>> +
>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>> +					prot);
>> +			if (ret)
>> +				goto fail;
>> +
>> +			offset += page_len;
>> +		}
>> +	} else {
>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>> +	}
>> +	goto out;
>> +
>> +fail:
>> +	/* undo mappings already done in case of error */
>> +	iommu_unmap(domain, iova, offset);
> 
> I think this would be cleaner if you stuck it in the loop above and removed
> all these labels:
> 
>   if (ret) {
> 	iommu_unmap(...);
> 	break;
>   }

Sure, I can do that.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Any more comments on this from anyone before I submit v5?

On 8/1/2014 9:44 AM, Olav Haugan wrote:
> Hi Will,
> 
> On 8/1/2014 1:22 AM, Will Deacon wrote:
>> Hi Olav,
>>
>> On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
>>> Mapping and unmapping are more often than not in the critical path.
>>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>>
>>> Instead of mapping a buffer one page at a time and requiring potentially
>>> expensive TLB operations for each page, this function allows the driver
>>> to map all pages in one go and defer TLB maintenance until after all
>>> pages have been mapped.
>>>
>>> Additionally, the mapping operation would be faster in general since
>>> clients does not have to keep calling map API over and over again for
>>> each physically contiguous chunk of memory that needs to be mapped to a
>>> virtually contiguous region.
>>
>> Just a couple of minor comments, but I think this is almost there now.
>>
>>> Signed-off-by: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
>>> ---
>>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>>  2 files changed, 72 insertions(+)
>>>
>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>>> index 1698360..1d5dc2e 100644
>>> --- a/drivers/iommu/iommu.c
>>> +++ b/drivers/iommu/iommu.c
>>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>>  }
>>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>>  
>>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>>> +			struct scatterlist *sg, unsigned int nents,
>>> +			int prot, unsigned long flags)
>>> +{
>>
>> What do you anticipate passing in the flags parameter? I assume it's
>> something specific to the scatterlist, since we can't provide this to
>> iommu_map as it stands?
> 
> Initially the flags argument is planned to be used by clients to
> indicate to the driver that no TLB operation is necessary. This allows
> clients to for example map/unmap multiple scatter-gather lists without
> doing expensive TLB invalidate operations for each call but just do this
> at the last mapping/unmapping call instead. I believe Rob Clark was
> looking for this feature and I can see the benefit for our use cases also.
> 
>>> +	int ret = 0;
>>> +	unsigned long offset = 0;
>>> +
>>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>>> +		unsigned int i;
>>> +		struct scatterlist *s;
>>> +
>>> +		for_each_sg(sg, s, nents, i) {
>>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>>> +			size_t page_len = s->offset + s->length;
>>> +
>>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>>> +					prot);
>>> +			if (ret)
>>> +				goto fail;
>>> +
>>> +			offset += page_len;
>>> +		}
>>> +	} else {
>>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>>> +	}
>>> +	goto out;
>>> +
>>> +fail:
>>> +	/* undo mappings already done in case of error */
>>> +	iommu_unmap(domain, iova, offset);
>>
>> I think this would be cleaner if you stuck it in the loop above and removed
>> all these labels:
>>
>>   if (ret) {
>> 	iommu_unmap(...);
>> 	break;
>>   }
> 
> Sure, I can do that.
> 
> Thanks,
> 
> Olav
> 


Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

Any more comments on this from anyone before I submit v5?

On 8/1/2014 9:44 AM, Olav Haugan wrote:
> Hi Will,
> 
> On 8/1/2014 1:22 AM, Will Deacon wrote:
>> Hi Olav,
>>
>> On Fri, Aug 01, 2014 at 01:54:44AM +0100, Olav Haugan wrote:
>>> Mapping and unmapping are more often than not in the critical path.
>>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>>
>>> Instead of mapping a buffer one page at a time and requiring potentially
>>> expensive TLB operations for each page, this function allows the driver
>>> to map all pages in one go and defer TLB maintenance until after all
>>> pages have been mapped.
>>>
>>> Additionally, the mapping operation would be faster in general since
>>> clients does not have to keep calling map API over and over again for
>>> each physically contiguous chunk of memory that needs to be mapped to a
>>> virtually contiguous region.
>>
>> Just a couple of minor comments, but I think this is almost there now.
>>
>>> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
>>> ---
>>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>>  2 files changed, 72 insertions(+)
>>>
>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>>> index 1698360..1d5dc2e 100644
>>> --- a/drivers/iommu/iommu.c
>>> +++ b/drivers/iommu/iommu.c
>>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>>  }
>>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>>  
>>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>>> +			struct scatterlist *sg, unsigned int nents,
>>> +			int prot, unsigned long flags)
>>> +{
>>
>> What do you anticipate passing in the flags parameter? I assume it's
>> something specific to the scatterlist, since we can't provide this to
>> iommu_map as it stands?
> 
> Initially the flags argument is planned to be used by clients to
> indicate to the driver that no TLB operation is necessary. This allows
> clients to for example map/unmap multiple scatter-gather lists without
> doing expensive TLB invalidate operations for each call but just do this
> at the last mapping/unmapping call instead. I believe Rob Clark was
> looking for this feature and I can see the benefit for our use cases also.
> 
>>> +	int ret = 0;
>>> +	unsigned long offset = 0;
>>> +
>>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>>> +		unsigned int i;
>>> +		struct scatterlist *s;
>>> +
>>> +		for_each_sg(sg, s, nents, i) {
>>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>>> +			size_t page_len = s->offset + s->length;
>>> +
>>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>>> +					prot);
>>> +			if (ret)
>>> +				goto fail;
>>> +
>>> +			offset += page_len;
>>> +		}
>>> +	} else {
>>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>>> +	}
>>> +	goto out;
>>> +
>>> +fail:
>>> +	/* undo mappings already done in case of error */
>>> +	iommu_unmap(domain, iova, offset);
>>
>> I think this would be cleaner if you stuck it in the loop above and removed
>> all these labels:
>>
>>   if (ret) {
>> 	iommu_unmap(...);
>> 	break;
>>   }
> 
> Sure, I can do that.
> 
> Thanks,
> 
> Olav
> 


Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Konrad Rzeszutek Wilk]

On Thu, Jul 31, 2014 at 05:54:44PM -0700, Olav Haugan wrote:
> Mapping and unmapping are more often than not in the critical path.
> map_sg and unmap_sg allows IOMMU driver implementations to optimize
> the process of mapping and unmapping buffers into the IOMMU page tables.
> 
> Instead of mapping a buffer one page at a time and requiring potentially
> expensive TLB operations for each page, this function allows the driver
> to map all pages in one go and defer TLB maintenance until after all
> pages have been mapped.
> 
> Additionally, the mapping operation would be faster in general since
> clients does not have to keep calling map API over and over again for
> each physically contiguous chunk of memory that needs to be mapped to a
> virtually contiguous region.

That is assuming that physical == bus topology.

> 
> Signed-off-by: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1698360..1d5dc2e 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>  }
>  EXPORT_SYMBOL_GPL(iommu_unmap);
>  
> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents,
> +			int prot, unsigned long flags)
> +{
> +	int ret = 0;
> +	unsigned long offset = 0;
> +
> +	if (unlikely(domain->ops->map_sg == NULL)) {
> +		unsigned int i;
> +		struct scatterlist *s;
> +
> +		for_each_sg(sg, s, nents, i) {
> +			phys_addr_t phys = page_to_phys(sg_page(s));
> +			size_t page_len = s->offset + s->length;
> +
> +			ret = iommu_map(domain, iova + offset, phys, page_len,
> +					prot);
> +			if (ret)
> +				goto fail;
> +
> +			offset += page_len;
> +		}

I think it would be better if you had an 'default_iommu_map_sg' with
the implementation above. And then the default ops->map_sg would point to
that and each IOMMU would over-write with its own version.

That way you don't need any of this 'if' and can have the 'iommu_map_sg'
be in the header file (either as static inline or an macro).


> +	} else {
> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
> +	}
> +	goto out;
> +
> +fail:
> +	/* undo mappings already done in case of error */
> +	iommu_unmap(domain, iova, offset);
> +out:
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_map_sg);
> +
> +int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
> +			size_t size, unsigned long flags)
> +{
> +	if (unlikely(domain->ops->unmap_sg == NULL))
> +		return iommu_unmap(domain, iova, size);
> +	else
> +		return domain->ops->unmap_sg(domain, iova, size, flags);
> +}
> +EXPORT_SYMBOL_GPL(iommu_unmap_sg);
>  
>  int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
>  			       phys_addr_t paddr, u64 size, int prot)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 20f9a52..66ad543 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -22,6 +22,7 @@
>  #include <linux/errno.h>
>  #include <linux/err.h>
>  #include <linux/types.h>
> +#include <linux/scatterlist.h>
>  #include <trace/events/iommu.h>
>  
>  #define IOMMU_READ	(1 << 0)
> @@ -93,6 +94,10 @@ enum iommu_attr {
>   * @detach_dev: detach device from an iommu domain
>   * @map: map a physically contiguous memory region to an iommu domain
>   * @unmap: unmap a physically contiguous memory region from an iommu domain
> + * @map_sg: map a scatter-gather list of physically contiguous memory chunks
> + * to an iommu domain
> + * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
> + * chunks from an iommu domain
>   * @iova_to_phys: translate iova to physical address
>   * @domain_has_cap: domain capabilities query
>   * @add_device: add device to iommu grouping
> @@ -110,6 +115,11 @@ struct iommu_ops {
>  		   phys_addr_t paddr, size_t size, int prot);
>  	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
>  		     size_t size);
> +	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags);
> +	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
> +			size_t size, unsigned long flags);
>  	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
>  	int (*domain_has_cap)(struct iommu_domain *domain,
>  			      unsigned long cap);
> @@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
>  		     phys_addr_t paddr, size_t size, int prot);
>  extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>  		       size_t size);
> +extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags);
> +extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
> +				size_t size, unsigned long flags);
>  extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
>  extern int iommu_domain_has_cap(struct iommu_domain *domain,
>  				unsigned long cap);
> @@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>  	return -ENODEV;
>  }
>  
> +static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iommu_unmap_sg(struct iommu_domain *domain,
> +			unsigned long iova, size_t size, unsigned long flags)
> +{
> +	return -ENODEV;
> +}
> +
>  static inline int iommu_domain_window_enable(struct iommu_domain *domain,
>  					     u32 wnd_nr, phys_addr_t paddr,
>  					     u64 size, int prot)
> -- 
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
> 
> _______________________________________________
> iommu mailing list
> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Konrad Rzeszutek Wilk]

On Thu, Jul 31, 2014 at 05:54:44PM -0700, Olav Haugan wrote:
> Mapping and unmapping are more often than not in the critical path.
> map_sg and unmap_sg allows IOMMU driver implementations to optimize
> the process of mapping and unmapping buffers into the IOMMU page tables.
> 
> Instead of mapping a buffer one page at a time and requiring potentially
> expensive TLB operations for each page, this function allows the driver
> to map all pages in one go and defer TLB maintenance until after all
> pages have been mapped.
> 
> Additionally, the mapping operation would be faster in general since
> clients does not have to keep calling map API over and over again for
> each physically contiguous chunk of memory that needs to be mapped to a
> virtually contiguous region.

That is assuming that physical == bus topology.

> 
> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
> ---
>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1698360..1d5dc2e 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>  }
>  EXPORT_SYMBOL_GPL(iommu_unmap);
>  
> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents,
> +			int prot, unsigned long flags)
> +{
> +	int ret = 0;
> +	unsigned long offset = 0;
> +
> +	if (unlikely(domain->ops->map_sg == NULL)) {
> +		unsigned int i;
> +		struct scatterlist *s;
> +
> +		for_each_sg(sg, s, nents, i) {
> +			phys_addr_t phys = page_to_phys(sg_page(s));
> +			size_t page_len = s->offset + s->length;
> +
> +			ret = iommu_map(domain, iova + offset, phys, page_len,
> +					prot);
> +			if (ret)
> +				goto fail;
> +
> +			offset += page_len;
> +		}

I think it would be better if you had an 'default_iommu_map_sg' with
the implementation above. And then the default ops->map_sg would point to
that and each IOMMU would over-write with its own version.

That way you don't need any of this 'if' and can have the 'iommu_map_sg'
be in the header file (either as static inline or an macro).


> +	} else {
> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
> +	}
> +	goto out;
> +
> +fail:
> +	/* undo mappings already done in case of error */
> +	iommu_unmap(domain, iova, offset);
> +out:
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_map_sg);
> +
> +int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
> +			size_t size, unsigned long flags)
> +{
> +	if (unlikely(domain->ops->unmap_sg == NULL))
> +		return iommu_unmap(domain, iova, size);
> +	else
> +		return domain->ops->unmap_sg(domain, iova, size, flags);
> +}
> +EXPORT_SYMBOL_GPL(iommu_unmap_sg);
>  
>  int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
>  			       phys_addr_t paddr, u64 size, int prot)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 20f9a52..66ad543 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -22,6 +22,7 @@
>  #include <linux/errno.h>
>  #include <linux/err.h>
>  #include <linux/types.h>
> +#include <linux/scatterlist.h>
>  #include <trace/events/iommu.h>
>  
>  #define IOMMU_READ	(1 << 0)
> @@ -93,6 +94,10 @@ enum iommu_attr {
>   * @detach_dev: detach device from an iommu domain
>   * @map: map a physically contiguous memory region to an iommu domain
>   * @unmap: unmap a physically contiguous memory region from an iommu domain
> + * @map_sg: map a scatter-gather list of physically contiguous memory chunks
> + * to an iommu domain
> + * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
> + * chunks from an iommu domain
>   * @iova_to_phys: translate iova to physical address
>   * @domain_has_cap: domain capabilities query
>   * @add_device: add device to iommu grouping
> @@ -110,6 +115,11 @@ struct iommu_ops {
>  		   phys_addr_t paddr, size_t size, int prot);
>  	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
>  		     size_t size);
> +	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags);
> +	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
> +			size_t size, unsigned long flags);
>  	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
>  	int (*domain_has_cap)(struct iommu_domain *domain,
>  			      unsigned long cap);
> @@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
>  		     phys_addr_t paddr, size_t size, int prot);
>  extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>  		       size_t size);
> +extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags);
> +extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
> +				size_t size, unsigned long flags);
>  extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
>  extern int iommu_domain_has_cap(struct iommu_domain *domain,
>  				unsigned long cap);
> @@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>  	return -ENODEV;
>  }
>  
> +static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
> +			struct scatterlist *sg, unsigned int nents, int prot,
> +			unsigned long flags)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int iommu_unmap_sg(struct iommu_domain *domain,
> +			unsigned long iova, size_t size, unsigned long flags)
> +{
> +	return -ENODEV;
> +}
> +
>  static inline int iommu_domain_window_enable(struct iommu_domain *domain,
>  					     u32 wnd_nr, phys_addr_t paddr,
>  					     u64 size, int prot)
> -- 
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
> 
> _______________________________________________
> iommu mailing list
> iommu at lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/5/2014 8:13 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, Jul 31, 2014 at 05:54:44PM -0700, Olav Haugan wrote:
>> Mapping and unmapping are more often than not in the critical path.
>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>
>> Instead of mapping a buffer one page at a time and requiring potentially
>> expensive TLB operations for each page, this function allows the driver
>> to map all pages in one go and defer TLB maintenance until after all
>> pages have been mapped.
>>
>> Additionally, the mapping operation would be faster in general since
>> clients does not have to keep calling map API over and over again for
>> each physically contiguous chunk of memory that needs to be mapped to a
>> virtually contiguous region.
> 
> That is assuming that physical == bus topology.
> 
>>
>> Signed-off-by: Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
>> ---
>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>  2 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1698360..1d5dc2e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>  
>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents,
>> +			int prot, unsigned long flags)
>> +{
>> +	int ret = 0;
>> +	unsigned long offset = 0;
>> +
>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>> +		unsigned int i;
>> +		struct scatterlist *s;
>> +
>> +		for_each_sg(sg, s, nents, i) {
>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>> +			size_t page_len = s->offset + s->length;
>> +
>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>> +					prot);
>> +			if (ret)
>> +				goto fail;
>> +
>> +			offset += page_len;
>> +		}
> 
> I think it would be better if you had an 'default_iommu_map_sg' with
> the implementation above. And then the default ops->map_sg would point to
> that and each IOMMU would over-write with its own version.
> 
> That way you don't need any of this 'if' and can have the 'iommu_map_sg'
> be in the header file (either as static inline or an macro).

so you are suggesting that I check in "bus_set_iommu()" whether the
driver has set the map_sg/unmap_sg function pointers or not and if not
set it to the default? Is bus_set_iommu() the only way drivers can set
up the callbacks?

> 
>> +	} else {
>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>> +	}
>> +	goto out;
>> +
>> +fail:
>> +	/* undo mappings already done in case of error */
>> +	iommu_unmap(domain, iova, offset);
>> +out:
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_map_sg);
>> +
>> +int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
>> +			size_t size, unsigned long flags)
>> +{
>> +	if (unlikely(domain->ops->unmap_sg == NULL))
>> +		return iommu_unmap(domain, iova, size);
>> +	else
>> +		return domain->ops->unmap_sg(domain, iova, size, flags);
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_unmap_sg);
>>  
>>  int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
>>  			       phys_addr_t paddr, u64 size, int prot)
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 20f9a52..66ad543 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -22,6 +22,7 @@
>>  #include <linux/errno.h>
>>  #include <linux/err.h>
>>  #include <linux/types.h>
>> +#include <linux/scatterlist.h>
>>  #include <trace/events/iommu.h>
>>  
>>  #define IOMMU_READ	(1 << 0)
>> @@ -93,6 +94,10 @@ enum iommu_attr {
>>   * @detach_dev: detach device from an iommu domain
>>   * @map: map a physically contiguous memory region to an iommu domain
>>   * @unmap: unmap a physically contiguous memory region from an iommu domain
>> + * @map_sg: map a scatter-gather list of physically contiguous memory chunks
>> + * to an iommu domain
>> + * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
>> + * chunks from an iommu domain
>>   * @iova_to_phys: translate iova to physical address
>>   * @domain_has_cap: domain capabilities query
>>   * @add_device: add device to iommu grouping
>> @@ -110,6 +115,11 @@ struct iommu_ops {
>>  		   phys_addr_t paddr, size_t size, int prot);
>>  	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
>>  		     size_t size);
>> +	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags);
>> +	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
>> +			size_t size, unsigned long flags);
>>  	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
>>  	int (*domain_has_cap)(struct iommu_domain *domain,
>>  			      unsigned long cap);
>> @@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
>>  		     phys_addr_t paddr, size_t size, int prot);
>>  extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>>  		       size_t size);
>> +extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags);
>> +extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
>> +				size_t size, unsigned long flags);
>>  extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
>>  extern int iommu_domain_has_cap(struct iommu_domain *domain,
>>  				unsigned long cap);
>> @@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>>  	return -ENODEV;
>>  }
>>  
>> +static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags)
>> +{
>> +	return -ENODEV;
>> +}
>> +
>> +static inline int iommu_unmap_sg(struct iommu_domain *domain,
>> +			unsigned long iova, size_t size, unsigned long flags)
>> +{
>> +	return -ENODEV;
>> +}
>> +
>>  static inline int iommu_domain_window_enable(struct iommu_domain *domain,
>>  					     u32 wnd_nr, phys_addr_t paddr,
>>  					     u64 size, int prot)
>> -- 
>> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> hosted by The Linux Foundation
>>
>> _______________________________________________
>> iommu mailing list
>> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 


Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/5/2014 8:13 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, Jul 31, 2014 at 05:54:44PM -0700, Olav Haugan wrote:
>> Mapping and unmapping are more often than not in the critical path.
>> map_sg and unmap_sg allows IOMMU driver implementations to optimize
>> the process of mapping and unmapping buffers into the IOMMU page tables.
>>
>> Instead of mapping a buffer one page at a time and requiring potentially
>> expensive TLB operations for each page, this function allows the driver
>> to map all pages in one go and defer TLB maintenance until after all
>> pages have been mapped.
>>
>> Additionally, the mapping operation would be faster in general since
>> clients does not have to keep calling map API over and over again for
>> each physically contiguous chunk of memory that needs to be mapped to a
>> virtually contiguous region.
> 
> That is assuming that physical == bus topology.
> 
>>
>> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
>> ---
>>  drivers/iommu/iommu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/iommu.h | 28 ++++++++++++++++++++++++++++
>>  2 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 1698360..1d5dc2e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1088,6 +1088,50 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
>>  }
>>  EXPORT_SYMBOL_GPL(iommu_unmap);
>>  
>> +int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents,
>> +			int prot, unsigned long flags)
>> +{
>> +	int ret = 0;
>> +	unsigned long offset = 0;
>> +
>> +	if (unlikely(domain->ops->map_sg == NULL)) {
>> +		unsigned int i;
>> +		struct scatterlist *s;
>> +
>> +		for_each_sg(sg, s, nents, i) {
>> +			phys_addr_t phys = page_to_phys(sg_page(s));
>> +			size_t page_len = s->offset + s->length;
>> +
>> +			ret = iommu_map(domain, iova + offset, phys, page_len,
>> +					prot);
>> +			if (ret)
>> +				goto fail;
>> +
>> +			offset += page_len;
>> +		}
> 
> I think it would be better if you had an 'default_iommu_map_sg' with
> the implementation above. And then the default ops->map_sg would point to
> that and each IOMMU would over-write with its own version.
> 
> That way you don't need any of this 'if' and can have the 'iommu_map_sg'
> be in the header file (either as static inline or an macro).

so you are suggesting that I check in "bus_set_iommu()" whether the
driver has set the map_sg/unmap_sg function pointers or not and if not
set it to the default? Is bus_set_iommu() the only way drivers can set
up the callbacks?

> 
>> +	} else {
>> +		ret = domain->ops->map_sg(domain, iova, sg, nents, prot, flags);
>> +	}
>> +	goto out;
>> +
>> +fail:
>> +	/* undo mappings already done in case of error */
>> +	iommu_unmap(domain, iova, offset);
>> +out:
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_map_sg);
>> +
>> +int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
>> +			size_t size, unsigned long flags)
>> +{
>> +	if (unlikely(domain->ops->unmap_sg == NULL))
>> +		return iommu_unmap(domain, iova, size);
>> +	else
>> +		return domain->ops->unmap_sg(domain, iova, size, flags);
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_unmap_sg);
>>  
>>  int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
>>  			       phys_addr_t paddr, u64 size, int prot)
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 20f9a52..66ad543 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -22,6 +22,7 @@
>>  #include <linux/errno.h>
>>  #include <linux/err.h>
>>  #include <linux/types.h>
>> +#include <linux/scatterlist.h>
>>  #include <trace/events/iommu.h>
>>  
>>  #define IOMMU_READ	(1 << 0)
>> @@ -93,6 +94,10 @@ enum iommu_attr {
>>   * @detach_dev: detach device from an iommu domain
>>   * @map: map a physically contiguous memory region to an iommu domain
>>   * @unmap: unmap a physically contiguous memory region from an iommu domain
>> + * @map_sg: map a scatter-gather list of physically contiguous memory chunks
>> + * to an iommu domain
>> + * @unmap_sg: unmap a scatter-gather list of physically contiguous memory
>> + * chunks from an iommu domain
>>   * @iova_to_phys: translate iova to physical address
>>   * @domain_has_cap: domain capabilities query
>>   * @add_device: add device to iommu grouping
>> @@ -110,6 +115,11 @@ struct iommu_ops {
>>  		   phys_addr_t paddr, size_t size, int prot);
>>  	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
>>  		     size_t size);
>> +	int (*map_sg)(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags);
>> +	int (*unmap_sg)(struct iommu_domain *domain, unsigned long iova,
>> +			size_t size, unsigned long flags);
>>  	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
>>  	int (*domain_has_cap)(struct iommu_domain *domain,
>>  			      unsigned long cap);
>> @@ -153,6 +163,11 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
>>  		     phys_addr_t paddr, size_t size, int prot);
>>  extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>>  		       size_t size);
>> +extern int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags);
>> +extern int iommu_unmap_sg(struct iommu_domain *domain, unsigned long iova,
>> +				size_t size, unsigned long flags);
>>  extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
>>  extern int iommu_domain_has_cap(struct iommu_domain *domain,
>>  				unsigned long cap);
>> @@ -287,6 +302,19 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
>>  	return -ENODEV;
>>  }
>>  
>> +static inline int iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
>> +			struct scatterlist *sg, unsigned int nents, int prot,
>> +			unsigned long flags)
>> +{
>> +	return -ENODEV;
>> +}
>> +
>> +static inline int iommu_unmap_sg(struct iommu_domain *domain,
>> +			unsigned long iova, size_t size, unsigned long flags)
>> +{
>> +	return -ENODEV;
>> +}
>> +
>>  static inline int iommu_domain_window_enable(struct iommu_domain *domain,
>>  					     u32 wnd_nr, phys_addr_t paddr,
>>  					     u64 size, int prot)
>> -- 
>> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> hosted by The Linux Foundation
>>
>> _______________________________________________
>> iommu mailing list
>> iommu at lists.linux-foundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 


Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Joerg Roedel]

On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> so you are suggesting that I check in "bus_set_iommu()" whether the
> driver has set the map_sg/unmap_sg function pointers or not and if not
> set it to the default? Is bus_set_iommu() the only way drivers can set
> up the callbacks?

This doesn't work as the iommu_ops are now const. You have to either
update the iommu drivers individually to point to the default function,
or you do the check in the API function itself and fall back to the
default it no call-back is provided.


	Joerg

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Joerg Roedel]

On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> so you are suggesting that I check in "bus_set_iommu()" whether the
> driver has set the map_sg/unmap_sg function pointers or not and if not
> set it to the default? Is bus_set_iommu() the only way drivers can set
> up the callbacks?

This doesn't work as the iommu_ops are now const. You have to either
update the iommu drivers individually to point to the default function,
or you do the check in the API function itself and fall back to the
default it no call-back is provided.


	Joerg

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
>> so you are suggesting that I check in "bus_set_iommu()" whether the
>> driver has set the map_sg/unmap_sg function pointers or not and if not
>> set it to the default? Is bus_set_iommu() the only way drivers can set
>> up the callbacks?
> 
> This doesn't work as the iommu_ops are now const. You have to either
> update the iommu drivers individually to point to the default function,
> or you do the check in the API function itself and fall back to the
> default it no call-back is provided.
> 

Ok, then I think it is better to just leave the fallback where it is now
in the function itself.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
>> so you are suggesting that I check in "bus_set_iommu()" whether the
>> driver has set the map_sg/unmap_sg function pointers or not and if not
>> set it to the default? Is bus_set_iommu() the only way drivers can set
>> up the callbacks?
> 
> This doesn't work as the iommu_ops are now const. You have to either
> update the iommu drivers individually to point to the default function,
> or you do the check in the API function itself and fall back to the
> default it no call-back is provided.
> 

Ok, then I think it is better to just leave the fallback where it is now
in the function itself.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1137 bytes --]

On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> > On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> >> so you are suggesting that I check in "bus_set_iommu()" whether the
> >> driver has set the map_sg/unmap_sg function pointers or not and if not
> >> set it to the default? Is bus_set_iommu() the only way drivers can set
> >> up the callbacks?
> > 
> > This doesn't work as the iommu_ops are now const. You have to either
> > update the iommu drivers individually to point to the default function,
> > or you do the check in the API function itself and fall back to the
> > default it no call-back is provided.
> > 
> 
> Ok, then I think it is better to just leave the fallback where it is now
> in the function itself.

What Konrad was suggesting is what I also proposed. The idea is to
implement a fallback as standalone function, then make all drivers use
that by default in the struct iommu_ops that they register. When drivers
implement an optimized version they can simply replace the fallback
implementation with their own.

Thierry

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[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Thierry Reding]

On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> > On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> >> so you are suggesting that I check in "bus_set_iommu()" whether the
> >> driver has set the map_sg/unmap_sg function pointers or not and if not
> >> set it to the default? Is bus_set_iommu() the only way drivers can set
> >> up the callbacks?
> > 
> > This doesn't work as the iommu_ops are now const. You have to either
> > update the iommu drivers individually to point to the default function,
> > or you do the check in the API function itself and fall back to the
> > default it no call-back is provided.
> > 
> 
> Ok, then I think it is better to just leave the fallback where it is now
> in the function itself.

What Konrad was suggesting is what I also proposed. The idea is to
implement a fallback as standalone function, then make all drivers use
that by default in the struct iommu_ops that they register. When drivers
implement an optimized version they can simply replace the fallback
implementation with their own.

Thierry
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Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/6/2014 11:24 PM, Thierry Reding wrote:
> On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
>> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
>>> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
>>>> so you are suggesting that I check in "bus_set_iommu()" whether the
>>>> driver has set the map_sg/unmap_sg function pointers or not and if not
>>>> set it to the default? Is bus_set_iommu() the only way drivers can set
>>>> up the callbacks?
>>>
>>> This doesn't work as the iommu_ops are now const. You have to either
>>> update the iommu drivers individually to point to the default function,
>>> or you do the check in the API function itself and fall back to the
>>> default it no call-back is provided.
>>>
>>
>> Ok, then I think it is better to just leave the fallback where it is now
>> in the function itself.
> 
> What Konrad was suggesting is what I also proposed. The idea is to
> implement a fallback as standalone function, then make all drivers use
> that by default in the struct iommu_ops that they register. When drivers
> implement an optimized version they can simply replace the fallback
> implementation with their own.
> 

Ok, I can do that. I misunderstood the point of the fallback. I thought
the point of the fallback was to catch drivers that forget/neglect to
implement this callback. If that is not a concern I will update my patch
to create a separate function that I will point all existing drivers to.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Olav Haugan]

On 8/6/2014 11:24 PM, Thierry Reding wrote:
> On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
>> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
>>> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
>>>> so you are suggesting that I check in "bus_set_iommu()" whether the
>>>> driver has set the map_sg/unmap_sg function pointers or not and if not
>>>> set it to the default? Is bus_set_iommu() the only way drivers can set
>>>> up the callbacks?
>>>
>>> This doesn't work as the iommu_ops are now const. You have to either
>>> update the iommu drivers individually to point to the default function,
>>> or you do the check in the API function itself and fall back to the
>>> default it no call-back is provided.
>>>
>>
>> Ok, then I think it is better to just leave the fallback where it is now
>> in the function itself.
> 
> What Konrad was suggesting is what I also proposed. The idea is to
> implement a fallback as standalone function, then make all drivers use
> that by default in the struct iommu_ops that they register. When drivers
> implement an optimized version they can simply replace the fallback
> implementation with their own.
> 

Ok, I can do that. I misunderstood the point of the fallback. I thought
the point of the fallback was to catch drivers that forget/neglect to
implement this callback. If that is not a concern I will update my patch
to create a separate function that I will point all existing drivers to.

Thanks,

Olav

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Konrad Rzeszutek Wilk]

On Thu, Aug 07, 2014 at 02:52:56PM -0700, Olav Haugan wrote:
> On 8/6/2014 11:24 PM, Thierry Reding wrote:
> > On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
> >> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> >>> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> >>>> so you are suggesting that I check in "bus_set_iommu()" whether the
> >>>> driver has set the map_sg/unmap_sg function pointers or not and if not
> >>>> set it to the default? Is bus_set_iommu() the only way drivers can set
> >>>> up the callbacks?
> >>>
> >>> This doesn't work as the iommu_ops are now const. You have to either
> >>> update the iommu drivers individually to point to the default function,
> >>> or you do the check in the API function itself and fall back to the
> >>> default it no call-back is provided.
> >>>
> >>
> >> Ok, then I think it is better to just leave the fallback where it is now
> >> in the function itself.
> > 
> > What Konrad was suggesting is what I also proposed. The idea is to
> > implement a fallback as standalone function, then make all drivers use
> > that by default in the struct iommu_ops that they register. When drivers
> > implement an optimized version they can simply replace the fallback
> > implementation with their own.
> > 
> 
> Ok, I can do that. I misunderstood the point of the fallback. I thought
> the point of the fallback was to catch drivers that forget/neglect to
> implement this callback. If that is not a concern I will update my patch

Nah. We want those drivers to crash and burn so we can see that and
fix it. And by fix I meant it would just point do:

	.map_sg = generic_map_sg,
	.unmap_sg = generic_unmap_sg,

In other words, none of the function ops will have an NULL functions.

> to create a separate function that I will point all existing drivers to.

Excellent!
> 
> Thanks,
> 
> Olav
> 
> -- 
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation

[PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions

[Konrad Rzeszutek Wilk]

On Thu, Aug 07, 2014 at 02:52:56PM -0700, Olav Haugan wrote:
> On 8/6/2014 11:24 PM, Thierry Reding wrote:
> > On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
> >> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> >>> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> >>>> so you are suggesting that I check in "bus_set_iommu()" whether the
> >>>> driver has set the map_sg/unmap_sg function pointers or not and if not
> >>>> set it to the default? Is bus_set_iommu() the only way drivers can set
> >>>> up the callbacks?
> >>>
> >>> This doesn't work as the iommu_ops are now const. You have to either
> >>> update the iommu drivers individually to point to the default function,
> >>> or you do the check in the API function itself and fall back to the
> >>> default it no call-back is provided.
> >>>
> >>
> >> Ok, then I think it is better to just leave the fallback where it is now
> >> in the function itself.
> > 
> > What Konrad was suggesting is what I also proposed. The idea is to
> > implement a fallback as standalone function, then make all drivers use
> > that by default in the struct iommu_ops that they register. When drivers
> > implement an optimized version they can simply replace the fallback
> > implementation with their own.
> > 
> 
> Ok, I can do that. I misunderstood the point of the fallback. I thought
> the point of the fallback was to catch drivers that forget/neglect to
> implement this callback. If that is not a concern I will update my patch

Nah. We want those drivers to crash and burn so we can see that and
fix it. And by fix I meant it would just point do:

	.map_sg = generic_map_sg,
	.unmap_sg = generic_unmap_sg,

In other words, none of the function ops will have an NULL functions.

> to create a separate function that I will point all existing drivers to.

Excellent!
> 
> Thanks,
> 
> Olav
> 
> -- 
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation