On 18/08/2021 13:06, Xie Yongji wrote:
+
+static dma_addr_t
+vduse_domain_alloc_iova(struct iova_domain *iovad,
+ unsigned long size, unsigned long limit)
+{
+ unsigned long shift = iova_shift(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);
Whether it's proper to use this "fast" API or not here, this seems to be
copied verbatim from dma-iommu.c, which tells me that something should
be factored out.
Indeed, this rounding up seems a requirement of the rcache, so not sure
why this is not done there.
+ iova_pfn = alloc_iova_fast(iovad, iova_len, limit >> shift, true);
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