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powerpc/vfio_spapr_tce: Add reference counting to iommu_table

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So far iommu_table obejcts were only used in virtual mode and had
a single owner. We are going to change this by implementing in-kernel
acceleration of DMA mapping requests. The proposed acceleration
will handle requests in real mode and KVM will keep references to tables.

This adds a kref to iommu_table and defines new helpers to update it.
This replaces iommu_free_table() with iommu_tce_table_put() and makes
iommu_free_table() static. iommu_tce_table_get() is not used in this patch
but it will be in the following patch.

Since this touches prototypes, this also removes @node_name parameter as
it has never been really useful on powernv and carrying it for
the pseries platform code to iommu_free_table() seems to be quite
useless as well.

This should cause no behavioral change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Alexey Kardashevskiy
2017-03-22 15:21:50 +11:00
committed by Michael Ellerman
parent 11edf116e3
commit e5afdf9dd5
7 changed files with 37 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
arch/powerpc/kernel/iommu.c
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@@ -711,13 +711,13 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
return tbl;
}
void iommu_free_table(struct iommu_table *tbl, const char *node_name)
static void iommu_table_free(struct kref *kref)
{
unsigned long bitmap_sz;
unsigned int order;
struct iommu_table *tbl;
if (!tbl)
return;
tbl = container_of(kref, struct iommu_table, it_kref);
if (tbl->it_ops->free)
tbl->it_ops->free(tbl);
@@ -736,7 +736,7 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
/* verify that table contains no entries */
if (!bitmap_empty(tbl->it_map, tbl->it_size))
pr_warn("%s: Unexpected TCEs for %s\n", __func__, node_name);
pr_warn("%s: Unexpected TCEs\n", __func__);
/* calculate bitmap size in bytes */
bitmap_sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
@@ -748,7 +748,24 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
/* free table */
kfree(tbl);
}
EXPORT_SYMBOL_GPL(iommu_free_table);
struct iommu_table *iommu_tce_table_get(struct iommu_table *tbl)
{
if (kref_get_unless_zero(&tbl->it_kref))
return tbl;
return NULL;
}
EXPORT_SYMBOL_GPL(iommu_tce_table_get);
int iommu_tce_table_put(struct iommu_table *tbl)
{
if (WARN_ON(!tbl))
return 0;
return kref_put(&tbl->it_kref, iommu_table_free);
}
EXPORT_SYMBOL_GPL(iommu_tce_table_put);
/* Creates TCEs for a user provided buffer. The user buffer must be
* contiguous real kernel storage (not vmalloc). The address passed here