iommu: Introduce Interface for IOMMU TLB Flushing
With the current IOMMU-API the hardware TLBs have to be
flushed in every iommu_ops->unmap() call-back.
For unmapping large amounts of address space, like it
happens when a KVM domain with assigned devices is
destroyed, this causes thousands of unnecessary TLB flushes
in the IOMMU hardware because the unmap call-back runs for
every unmapped physical page.
With the TLB Flush Interface and the new iommu_unmap_fast()
function introduced here the need to clean the hardware TLBs
is removed from the unmapping code-path. Users of
iommu_unmap_fast() have to explicitly call the TLB-Flush
functions to sync the page-table changes to the hardware.
Three functions for TLB-Flushes are introduced:
* iommu_flush_tlb_all() - Flushes all TLB entries
associated with that
domain. TLBs entries are
flushed when this function
returns.
* iommu_tlb_range_add() - This will add a given
range to the flush queue
for this domain.
* iommu_tlb_sync() - Flushes all queued ranges from
the hardware TLBs. Returns when
the flush is finished.
The semantic of this interface is intentionally similar to
the iommu_gather_ops from the io-pgtable code.
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5499a03..31c2b1d 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -527,6 +527,8 @@
}
+ iommu_flush_tlb_all(domain);
+
out:
iommu_put_resv_regions(dev, &mappings);
@@ -1547,13 +1549,16 @@
}
EXPORT_SYMBOL_GPL(iommu_map);
-size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
+static size_t __iommu_unmap(struct iommu_domain *domain,
+ unsigned long iova, size_t size,
+ bool sync)
{
+ const struct iommu_ops *ops = domain->ops;
size_t unmapped_page, unmapped = 0;
- unsigned int min_pagesz;
unsigned long orig_iova = iova;
+ unsigned int min_pagesz;
- if (unlikely(domain->ops->unmap == NULL ||
+ if (unlikely(ops->unmap == NULL ||
domain->pgsize_bitmap == 0UL))
return -ENODEV;
@@ -1583,10 +1588,13 @@
while (unmapped < size) {
size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
- unmapped_page = domain->ops->unmap(domain, iova, pgsize);
+ unmapped_page = ops->unmap(domain, iova, pgsize);
if (!unmapped_page)
break;
+ if (sync && ops->iotlb_range_add)
+ ops->iotlb_range_add(domain, iova, pgsize);
+
pr_debug("unmapped: iova 0x%lx size 0x%zx\n",
iova, unmapped_page);
@@ -1594,11 +1602,27 @@
unmapped += unmapped_page;
}
+ if (sync && ops->iotlb_sync)
+ ops->iotlb_sync(domain);
+
trace_unmap(orig_iova, size, unmapped);
return unmapped;
}
+
+size_t iommu_unmap(struct iommu_domain *domain,
+ unsigned long iova, size_t size)
+{
+ return __iommu_unmap(domain, iova, size, true);
+}
EXPORT_SYMBOL_GPL(iommu_unmap);
+size_t iommu_unmap_fast(struct iommu_domain *domain,
+ unsigned long iova, size_t size)
+{
+ return __iommu_unmap(domain, iova, size, false);
+}
+EXPORT_SYMBOL_GPL(iommu_unmap_fast);
+
size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
struct scatterlist *sg, unsigned int nents, int prot)
{