From a639a8eecf2be962b5dcd38dedd8b6bd10c2354b Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Tue, 22 Dec 2015 16:06:49 +0100 Subject: [PATCH] iommu/amd: Preallocate dma_ops apertures based on dma_mask Preallocate between 4 and 8 apertures when a device gets it dma_mask. With more apertures we reduce the lock contention of the domain lock significantly. Signed-off-by: Joerg Roedel --- drivers/iommu/amd_iommu.c | 60 ++++++++++++++++++++++++++++++++++----- 1 file changed, 53 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index eed355c5211d..6f6502d9fd67 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -1892,6 +1892,23 @@ static void dma_ops_domain_free(struct dma_ops_domain *dom) kfree(dom); } +static int dma_ops_domain_alloc_apertures(struct dma_ops_domain *dma_dom, + int max_apertures) +{ + int ret, i, apertures; + + apertures = dma_dom->aperture_size >> APERTURE_RANGE_SHIFT; + ret = 0; + + for (i = apertures; i < max_apertures; ++i) { + ret = alloc_new_range(dma_dom, false, GFP_KERNEL); + if (ret) + break; + } + + return ret; +} + /* * Allocates a new protection domain usable for the dma_ops functions. * It also initializes the page table and the address allocator data @@ -2800,14 +2817,43 @@ static int amd_iommu_dma_supported(struct device *dev, u64 mask) return check_device(dev); } +static int set_dma_mask(struct device *dev, u64 mask) +{ + struct protection_domain *domain; + int max_apertures = 1; + + domain = get_domain(dev); + if (IS_ERR(domain)) + return PTR_ERR(domain); + + if (mask == DMA_BIT_MASK(64)) + max_apertures = 8; + else if (mask > DMA_BIT_MASK(32)) + max_apertures = 4; + + /* + * To prevent lock contention it doesn't make sense to allocate more + * apertures than online cpus + */ + if (max_apertures > num_online_cpus()) + max_apertures = num_online_cpus(); + + if (dma_ops_domain_alloc_apertures(domain->priv, max_apertures)) + dev_err(dev, "Can't allocate %d iommu apertures\n", + max_apertures); + + return 0; +} + static struct dma_map_ops amd_iommu_dma_ops = { - .alloc = alloc_coherent, - .free = free_coherent, - .map_page = map_page, - .unmap_page = unmap_page, - .map_sg = map_sg, - .unmap_sg = unmap_sg, - .dma_supported = amd_iommu_dma_supported, + .alloc = alloc_coherent, + .free = free_coherent, + .map_page = map_page, + .unmap_page = unmap_page, + .map_sg = map_sg, + .unmap_sg = unmap_sg, + .dma_supported = amd_iommu_dma_supported, + .set_dma_mask = set_dma_mask, }; int __init amd_iommu_init_api(void) -- 2.20.1