Re: [PATCH 1/5] iova: Move fast alloc size roundup into alloc_iova_fast()

Michael S. Tsirkin
2021-10-18T15:42:36Z

On Fri, Sep 24, 2021 at 06:01:53PM +0800, 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.
>
> Signed-off-by: John Garry <john.garry@huawei.com>

for vdpa code:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
> drivers/iommu/dma-iommu.c | 8 --------
> drivers/iommu/iova.c | 9 +++++++++
> drivers/vdpa/vdpa_user/iova_domain.c | 8 --------
> 3 files changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 896bea04c347..a99b3445fef8 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -444,14 +444,6 @@ 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;
> --
> 2.26.2