Extend the calculation of 'count' in iommu_pgsize() so that it takes
larger page sizes into consideration and returns a value which will
allow a larger page size to be used on the next call.
Signed-off-by: Will Deacon <w...@kernel.org>
---
drivers/iommu/iommu.c | 36 ++++++++++++++++++++++++++++++++----
1 file changed, 32 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index fe186691fc21..0572a4dcd9e2 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2360,9 +2360,9 @@ EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
phys_addr_t paddr, size_t size, size_t *count)
{
- unsigned int pgsize_idx;
+ unsigned int pgsize_idx, pgsize_idx_next;
unsigned long pgsizes;
- size_t pgsize;
+ size_t offset, pgsize, pgsize_next;
phys_addr_t addr_merge = paddr | iova;
/* Page sizes supported by the hardware and small enough for @size */
@@ -2378,9 +2378,37 @@ static size_t iommu_pgsize(struct iommu_domain *domain,
unsigned long iova,
/* Pick the biggest page size remaining */
pgsize_idx = __fls(pgsizes);
pgsize = BIT(pgsize_idx);
+ if (!count)
+ return pgsize;
- if (count)
- *count = size >> pgsize_idx;
+
+ /* Find the next biggest support page size, if it exists */
+ pgsizes = domain->pgsize_bitmap & ~GENMASK(pgsize_idx, 0);
+ if (!pgsizes)
+ goto out_set_count;
+
+ pgsize_idx_next = __ffs(pgsizes);
+ pgsize_next = BIT(pgsize_idx_next);
+
+ /*
+ * There's no point trying a bigger page size unless the virtual
+ * and physical addresses are similarly offset within the larger page.
+ */
+ if ((iova ^ paddr) & (pgsize_next - 1))
+ goto out_set_count;
+
+ /* Calculate the offset to the next page size alignment boundary */
+ offset = pgsize_next - (addr_merge & (pgsize_next - 1));
+
+ /*
+ * If size is big enough to accomodate the larger page, reduce
+ * the number of smaller pages.
+ */
+ if (offset + pgsize_next <= size)
+ size = offset;
+
+out_set_count:
+ *count = size >> pgsize_idx;
return pgsize;
}
--
2.31.0.291.g576ba9dcdaf-goog
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