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 <jroedel@suse.de>

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index eed355c5211dd8f47fe11f3b6a95836165f27514..6f6502d9fd6739f2d048fe553beb1d30ec4d66d9 100644 (file)
--- 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)