Commit c208916f authored by Robin Murphy's avatar Robin Murphy Committed by Joerg Roedel
Browse files

iommu: Express DMA strictness via the domain type 



Eliminate the iommu_get_dma_strict() indirection and pipe the
information through the domain type from the beginning. Besides
the flow simplification this also has several nice side-effects:

 - Automatically implies strict mode for untrusted devices by
   virtue of their IOMMU_DOMAIN_DMA override.
 - Ensures that we only end up using flush queues for drivers
   which are aware of them and can actually benefit.
 - Allows us to handle flush queue init failure by falling back
   to strict mode instead of leaving it to possibly blow up later.

Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/47083d69155577f1367877b1594921948c366eb3.1628682049.git.robin.murphy@arm.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 78ca0784

drivers/iommu/dma-iommu.c

+6 −4
Original line number Diff line number Diff line
@@ -370,14 +370,16 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, 


	init_iova_domain(iovad, 1UL << order, base_pfn);



	if (!cookie->fq_domain && !dev_is_untrusted(dev) &&

	    domain->ops->flush_iotlb_all && !iommu_get_dma_strict(domain)) {

	/* If the FQ fails we can simply fall back to strict mode */

	if (domain->type == IOMMU_DOMAIN_DMA_FQ && !cookie->fq_domain) {

		if (init_iova_flush_queue(iovad, iommu_dma_flush_iotlb_all,

					  iommu_dma_entry_dtor))

					  iommu_dma_entry_dtor)) {

			pr_warn("iova flush queue initialization failed\n");

		else

			domain->type = IOMMU_DOMAIN_DMA;

		} else {

			cookie->fq_domain = domain;

		}

	}



	return iova_reserve_iommu_regions(dev, domain);

}

drivers/iommu/iommu.c

+5 −9
Original line number Diff line number Diff line
@@ -136,6 +136,9 @@ static int __init iommu_subsys_init(void) 
		}

	}



	if (!iommu_default_passthrough() && !iommu_dma_strict)

		iommu_def_domain_type = IOMMU_DOMAIN_DMA_FQ;



	pr_info("Default domain type: %s %s\n",

		iommu_domain_type_str(iommu_def_domain_type),

		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
@@ -355,17 +358,10 @@ early_param("iommu.strict", iommu_dma_setup); 
void iommu_set_dma_strict(void)

{

	iommu_dma_strict = true;

	if (iommu_def_domain_type == IOMMU_DOMAIN_DMA_FQ)

		iommu_def_domain_type = IOMMU_DOMAIN_DMA;

}



bool iommu_get_dma_strict(struct iommu_domain *domain)

{

	/* only allow lazy flushing for DMA domains */

	if (domain->type == IOMMU_DOMAIN_DMA)

		return iommu_dma_strict;

	return true;

}

EXPORT_SYMBOL_GPL(iommu_get_dma_strict);



static ssize_t iommu_group_attr_show(struct kobject *kobj,

				     struct attribute *__attr, char *buf)

{

include/linux/iommu.h

+0 −1
Original line number Diff line number Diff line
@@ -504,7 +504,6 @@ int iommu_set_pgtable_quirks(struct iommu_domain *domain, 
		unsigned long quirks);



void iommu_set_dma_strict(void);

bool iommu_get_dma_strict(struct iommu_domain *domain);



extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,

			      unsigned long iova, int flags);