Re: [PATCH v2] iova: Move fast alloc size roundup into alloc_iova_fast()

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On 2021-12-07 11:17, John Garry wrote:
It really is a property of the IOVA rcache code that we need to alloc a
power-of-2 size, so relocate the functionality to resize into
alloc_iova_fast(), rather than the callsites.

I'd still much prefer to resolve the issue that there shouldn't *be* more than one caller in the first place, but hey.

Acked-by: Robin Murphy <robin.murphy@xxxxxxx>

Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Reviewed-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
Differences to v1:
- Separate out from original series which conflicts with Robin's IOVA FQ work:
   https://lore.kernel.org/linux-iommu/1632477717-5254-1-git-send-email-john.garry@xxxxxxxxxx/
- Add tags - thanks!

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index b42e38a0dbe2..84dee53fe892 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -442,14 +442,6 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
shift = iova_shift(iovad);
  	iova_len = size >> shift;
-	/*
-	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
-	 * will come back to bite us badly, so we have to waste a bit of space
-	 * rounding up anything cacheable to make sure that can't happen. The
-	 * order of the unadjusted size will still match upon freeing.
-	 */
-	if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
-		iova_len = roundup_pow_of_two(iova_len);
dma_limit = min_not_zero(dma_limit, dev->bus_dma_limit); diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 9e8bc802ac05..ff567cbc42f7 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -497,6 +497,15 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
  	unsigned long iova_pfn;
  	struct iova *new_iova;
+ /*
+	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
+	 * will come back to bite us badly, so we have to waste a bit of space
+	 * rounding up anything cacheable to make sure that can't happen. The
+	 * order of the unadjusted size will still match upon freeing.
+	 */
+	if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
+		size = roundup_pow_of_two(size);
+
  	iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1);
  	if (iova_pfn)
  		return iova_pfn;
diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
index 1daae2608860..2b1143f11d8f 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.c
+++ b/drivers/vdpa/vdpa_user/iova_domain.c
@@ -292,14 +292,6 @@ vduse_domain_alloc_iova(struct iova_domain *iovad,
  	unsigned long iova_len = iova_align(iovad, size) >> shift;
  	unsigned long iova_pfn;
- /*
-	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
-	 * will come back to bite us badly, so we have to waste a bit of space
-	 * rounding up anything cacheable to make sure that can't happen. The
-	 * order of the unadjusted size will still match upon freeing.
-	 */
-	if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
-		iova_len = roundup_pow_of_two(iova_len);
  	iova_pfn = alloc_iova_fast(iovad, iova_len, limit >> shift, true);
return iova_pfn << shift;

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