linux-kernel - [PATCH 14/23] iommu: Introduce explicit type for non-strict DMA domains

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Message-Id: <25ff384e3d21e4973a95713ee00aed2a2c68ae7d.1626888445.git.robin.murphy@arm.com>
Date:   Wed, 21 Jul 2021 19:20:25 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     joro@...tes.org, will@...nel.org
Cc:     iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        suravee.suthikulpanit@....com, baolu.lu@...ux.intel.com,
        john.garry@...wei.com, dianders@...omium.org
Subject: [PATCH 14/23] iommu: Introduce explicit type for non-strict DMA domains

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@....com>
---
 drivers/iommu/dma-iommu.c | 2 +-
 drivers/iommu/iommu.c     | 6 +++++-
 include/linux/iommu.h     | 6 ++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index e28396cea6eb..b1af1ff324c5 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 (domain->type & __IOMMU_DOMAIN_DMA_API) {
 		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 e23d0c9be9db..8333c334891e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -114,6 +114,7 @@ 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";
@@ -547,6 +548,9 @@ 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);
@@ -1942,7 +1946,7 @@ 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 ((type & __IOMMU_DOMAIN_DMA_API) && iommu_get_dma_cookie(domain)) {
 		iommu_domain_free(domain);
 		domain = NULL;
 	}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 007662b65474..56519110d43f 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;
-- 
2.25.1