[PATCH v2 14/24] iommu: Introduce explicit type for non-strict DMA domains

Robin Murphy
2021-07-28T16:07:33Z

Promote the difference between strict and non-strict DMA domains from an
internal detail to a distinct domain feature and type, to pave the road
for exposing it through the sysfs default domain interface.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
drivers/iommu/dma-iommu.c | 2 +-
drivers/iommu/iommu.c | 8 ++++++--
include/linux/iommu.h | 11 +++++++++++
3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index e28396cea6eb..8b3545c01077 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1311,7 +1311,7 @@ void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit)
* The IOMMU core code allocates the default DMA domain, which the
* underlying IOMMU driver needs to support via the dma-iommu layer.
*/
- if (domain->type == IOMMU_DOMAIN_DMA) {
+ if (iommu_is_dma_domain(domain)) {
if (iommu_dma_init_domain(domain, dma_base, dma_limit, dev))
goto out_err;
dev->dma_ops = &iommu_dma_ops;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index fa8109369f74..982545234cf3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -115,6 +115,7 @@ static const char *iommu_domain_type_str(unsigned int t)
case IOMMU_DOMAIN_UNMANAGED:
return "Unmanaged";
case IOMMU_DOMAIN_DMA:
+ case IOMMU_DOMAIN_DMA_FQ:
return "Translated";
default:
return "Unknown";
@@ -552,6 +553,9 @@ static ssize_t iommu_group_show_type(struct iommu_group *group,
case IOMMU_DOMAIN_DMA:
type = "DMA\n";
break;
+ case IOMMU_DOMAIN_DMA_FQ:
+ type = "DMA-FQ\n";
+ break;
}
}
mutex_unlock(&group->mutex);
@@ -765,7 +769,7 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
unsigned long pg_size;
int ret = 0;

- if (!domain || domain->type != IOMMU_DOMAIN_DMA)
+ if (!domain || !iommu_is_dma_domain(domain))
return 0;

BUG_ON(!domain->pgsize_bitmap);
@@ -1947,7 +1951,7 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
/* Assume all sizes by default; the driver may override this later */
domain->pgsize_bitmap = bus->iommu_ops->pgsize_bitmap;

- if (type == IOMMU_DOMAIN_DMA && iommu_get_dma_cookie(domain)) {
+ if (iommu_is_dma_domain(domain) && iommu_get_dma_cookie(domain)) {
iommu_domain_free(domain);
domain = NULL;
}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 141779d76035..046ba4d54cd2 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -61,6 +61,7 @@ struct iommu_domain_geometry {
#define __IOMMU_DOMAIN_DMA_API (1U << 1) /* Domain for use in DMA-API
implementation */
#define __IOMMU_DOMAIN_PT (1U << 2) /* Domain is identity mapped */
+#define __IOMMU_DOMAIN_DMA_FQ (1U << 3) /* DMA-API uses flush queue */

/*
* This are the possible domain-types
@@ -73,12 +74,17 @@ struct iommu_domain_geometry {
* IOMMU_DOMAIN_DMA - Internally used for DMA-API implementations.
* This flag allows IOMMU drivers to implement
* certain optimizations for these domains
+ * IOMMU_DOMAIN_DMA_FQ - As above, but definitely using batched TLB
+ * invalidation.
*/
#define IOMMU_DOMAIN_BLOCKED (0U)
#define IOMMU_DOMAIN_IDENTITY (__IOMMU_DOMAIN_PT)
#define IOMMU_DOMAIN_UNMANAGED (__IOMMU_DOMAIN_PAGING)
#define IOMMU_DOMAIN_DMA (__IOMMU_DOMAIN_PAGING | \
__IOMMU_DOMAIN_DMA_API)
+#define IOMMU_DOMAIN_DMA_FQ (__IOMMU_DOMAIN_PAGING | \
+ __IOMMU_DOMAIN_DMA_API | \
+ __IOMMU_DOMAIN_DMA_FQ)

struct iommu_domain {
unsigned type;
@@ -90,6 +96,11 @@ struct iommu_domain {
struct iommu_dma_cookie *iova_cookie;
};

+static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
+{
+ return domain->type & __IOMMU_DOMAIN_DMA_API;
+}
+
enum iommu_cap {
IOMMU_CAP_CACHE_COHERENCY, /* IOMMU can enforce cache coherent DMA
transactions */
--
2.25.1