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Subject[PATCH v3 7/7] iommu/dma: Add IOMMU op to choose lazy domain type
Date
With two flush queue variants add an IOMMU operation that allows the
IOMMU driver to choose its preferred flush queue variant on a per device
basis. For s390 use this callback to choose the single queue variant
whenever the device requires explicit IOTLB flushes on map indicating
that we're running in a paged memory guest with expensive IOTLB flushes.

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
drivers/iommu/iommu.c | 13 +++++++++++++
drivers/iommu/s390-iommu.c | 11 +++++++++++
include/linux/iommu.h | 5 +++++
3 files changed, 29 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 7ae2ff35b88e..c4699a0e5feb 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1616,6 +1616,16 @@ static int iommu_get_def_domain_type(struct device *dev)
return 0;
}

+static int iommu_get_lazy_domain_type(struct device *dev)
+{
+ const struct iommu_ops *ops = dev_iommu_ops(dev);
+
+ if (ops->lazy_domain_type)
+ return ops->lazy_domain_type(dev);
+
+ return 0;
+}
+
static int iommu_group_alloc_default_domain(struct bus_type *bus,
struct iommu_group *group,
unsigned int type)
@@ -1649,6 +1659,9 @@ static int iommu_alloc_default_domain(struct iommu_group *group,

type = iommu_get_def_domain_type(dev) ? : iommu_def_domain_type;

+ if (!!(type & __IOMMU_DOMAIN_DMA_LAZY))
+ type = iommu_get_lazy_domain_type(dev) ? : type;
+
return iommu_group_alloc_default_domain(dev->bus, group, type);
}

diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
index 122219b3e89f..2575acd081b5 100644
--- a/drivers/iommu/s390-iommu.c
+++ b/drivers/iommu/s390-iommu.c
@@ -459,6 +459,16 @@ static void s390_iommu_get_resv_regions(struct device *dev,
}
}

+static int s390_iommu_lazy_domain_type(struct device *dev)
+{
+ struct zpci_dev *zdev = to_zpci_dev(dev);
+
+ if (zdev->tlb_refresh)
+ return IOMMU_DOMAIN_DMA_SQ;
+
+ return IOMMU_DOMAIN_DMA_FQ;
+}
+
static struct iommu_device *s390_iommu_probe_device(struct device *dev)
{
struct zpci_dev *zdev;
@@ -798,6 +808,7 @@ static const struct iommu_ops s390_iommu_ops = {
.device_group = generic_device_group,
.pgsize_bitmap = SZ_4K,
.get_resv_regions = s390_iommu_get_resv_regions,
+ .lazy_domain_type = s390_iommu_lazy_domain_type,
.default_domain_ops = &(const struct iommu_domain_ops) {
.attach_dev = s390_iommu_attach_device,
.detach_dev = s390_iommu_detach_device,
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 74cee59516aa..aec895087f63 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -250,6 +250,10 @@ struct iommu_iotlb_gather {
* - IOMMU_DOMAIN_IDENTITY: must use an identity domain
* - IOMMU_DOMAIN_DMA: must use a dma domain
* - 0: use the default setting
+ * @lazy_domain_type: Domain type for lazy TLB invalidation, return value:
+ * - IOMMU_DOMAIN_DMA_FQ: Use per-CPU flush queue
+ * - IOMMU_DOMAIN_DMA_SQ: Use single flush queue
+ * - 0: use the default setting
* @default_domain_ops: the default ops for domains
* @remove_dev_pasid: Remove any translation configurations of a specific
* pasid, so that any DMA transactions with this pasid
@@ -283,6 +287,7 @@ struct iommu_ops {
struct iommu_page_response *msg);

int (*def_domain_type)(struct device *dev);
+ int (*lazy_domain_type)(struct device *dev);
void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);

const struct iommu_domain_ops *default_domain_ops;
--
2.34.1
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