[PATCH v4 3/7] iommu: Improve iommu_iotlb_gather helpers

Nadav Amit
2021-06-16T17:34:39Z

From: Robin Murphy <robin.murphy@arm.com>

The Mediatek driver is not the only one which might want a basic
address-based gathering behaviour, so although it's arguably simple
enough to open-code, let's factor it out for the sake of cleanliness.
Let's also take this opportunity to document the intent of these
helpers for clarity.

Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Jiajun Cao <caojiajun@vmware.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Nadav Amit <namit@vmware.com>

---

Changes from Robin's version:
* Added iommu_iotlb_gather_add_range() stub !CONFIG_IOMMU_API
* Use iommu_iotlb_gather_add_range() in iommu_iotlb_gather_add_page()
---
drivers/iommu/mtk_iommu.c | 6 +-----
include/linux/iommu.h | 38 +++++++++++++++++++++++++++++++++-----
2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index e06b8a0e2b56..cd457487ce81 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -521,12 +521,8 @@ static size_t mtk_iommu_unmap(struct iommu_domain *domain,
struct iommu_iotlb_gather *gather)
{
struct mtk_iommu_domain *dom = to_mtk_domain(domain);
- unsigned long end = iova + size - 1;

- if (gather->start > iova)
- gather->start = iova;
- if (gather->end < end)
- gather->end = end;
+ iommu_iotlb_gather_add_range(gather, iova, size);
return dom->iop->unmap(dom->iop, iova, size, gather);
}

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..e554871db46f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -497,6 +497,38 @@ static inline void iommu_iotlb_sync(struct iommu_domain *domain,
iommu_iotlb_gather_init(iotlb_gather);
}

+/**
+ * iommu_iotlb_gather_add_range - Gather for address-based TLB invalidation
+ * @gather: TLB gather data
+ * @iova: start of page to invalidate
+ * @size: size of page to invalidate
+ *
+ * Helper for IOMMU drivers to build arbitrarily-sized invalidation commands
+ * where only the address range matters, and simply minimising intermediate
+ * syncs is preferred.
+ */
+static inline void iommu_iotlb_gather_add_range(struct iommu_iotlb_gather *gather,
+ unsigned long iova, size_t size)
+{
+ unsigned long end = iova + size - 1;
+
+ if (gather->start > iova)
+ gather->start = iova;
+ if (gather->end < end)
+ gather->end = end;
+}
+
+/**
+ * iommu_iotlb_gather_add_page - Gather for page-based TLB invalidation
+ * @domain: IOMMU domain to be invalidated
+ * @gather: TLB gather data
+ * @iova: start of page to invalidate
+ * @size: size of page to invalidate
+ *
+ * Helper for IOMMU drivers to build invalidation commands based on individual
+ * pages, or with page size/table level hints which cannot be gathered if they
+ * differ.
+ */
static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
struct iommu_iotlb_gather *gather,
unsigned long iova, size_t size)
@@ -515,11 +547,7 @@ static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
gather->pgsize = size;
}

- if (gather->end < end)
- gather->end = end;
-
- if (gather->start > start)
- gather->start = start;
+ iommu_iotlb_gather_add_range(gather, iova, size);
}

/* PCI device grouping function */
--
2.25.1