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Commit a639a8ee authored by Joerg Roedel's avatar Joerg Roedel
Browse files

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: default avatarJoerg Roedel <jroedel@suse.de>
parent 7b5e25b8

drivers/iommu/amd_iommu.c

+53 −7
Original line number Diff line number Diff line
@@ -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
@@ -2800,6 +2817,34 @@ 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,
@@ -2808,6 +2853,7 @@ static struct dma_map_ops amd_iommu_dma_ops = { 
	.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)