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Commit add02cfd authored by Joerg Roedel's avatar Joerg Roedel
Browse files

iommu: Introduce Interface for IOMMU TLB Flushing 



With the current IOMMU-API the hardware TLBs have to be
flushed in every iommu_ops->unmap() call-back.

For unmapping large amounts of address space, like it
happens when a KVM domain with assigned devices is
destroyed, this causes thousands of unnecessary TLB flushes
in the IOMMU hardware because the unmap call-back runs for
every unmapped physical page.

With the TLB Flush Interface and the new iommu_unmap_fast()
function introduced here the need to clean the hardware TLBs
is removed from the unmapping code-path. Users of
iommu_unmap_fast() have to explicitly call the TLB-Flush
functions to sync the page-table changes to the hardware.

Three functions for TLB-Flushes are introduced:

	* iommu_flush_tlb_all() - Flushes all TLB entries
	                          associated with that
				  domain. TLBs entries are
				  flushed when this function
				  returns.

	* iommu_tlb_range_add() - This will add a given
				  range to the flush queue
				  for this domain.

	* iommu_tlb_sync() - Flushes all queued ranges from
			     the hardware TLBs. Returns when
			     the flush is finished.

The semantic of this interface is intentionally similar to
the iommu_gather_ops from the io-pgtable code.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 0688a099

drivers/iommu/iommu.c

+28 −4
Original line number Diff line number Diff line
@@ -527,6 +527,8 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group, 


	}



	iommu_flush_tlb_all(domain);



out:

	iommu_put_resv_regions(dev, &mappings);
@@ -1547,13 +1549,16 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova, 
}

EXPORT_SYMBOL_GPL(iommu_map);



size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)

static size_t __iommu_unmap(struct iommu_domain *domain,

			    unsigned long iova, size_t size,

			    bool sync)

{

	const struct iommu_ops *ops = domain->ops;

	size_t unmapped_page, unmapped = 0;

	unsigned int min_pagesz;

	unsigned long orig_iova = iova;

	unsigned int min_pagesz;



	if (unlikely(domain->ops->unmap == NULL ||

	if (unlikely(ops->unmap == NULL ||

		     domain->pgsize_bitmap == 0UL))

		return -ENODEV;
@@ -1583,10 +1588,13 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size) 
	while (unmapped < size) {

		size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);



		unmapped_page = domain->ops->unmap(domain, iova, pgsize);

		unmapped_page = ops->unmap(domain, iova, pgsize);

		if (!unmapped_page)

			break;



		if (sync && ops->iotlb_range_add)

			ops->iotlb_range_add(domain, iova, pgsize);



		pr_debug("unmapped: iova 0x%lx size 0x%zx\n",

			 iova, unmapped_page);
@@ -1594,11 +1602,27 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size) 
		unmapped += unmapped_page;

	}



	if (sync && ops->iotlb_sync)

		ops->iotlb_sync(domain);



	trace_unmap(orig_iova, size, unmapped);

	return unmapped;

}



size_t iommu_unmap(struct iommu_domain *domain,

		   unsigned long iova, size_t size)

{

	return __iommu_unmap(domain, iova, size, true);

}

EXPORT_SYMBOL_GPL(iommu_unmap);



size_t iommu_unmap_fast(struct iommu_domain *domain,

			unsigned long iova, size_t size)

{

	return __iommu_unmap(domain, iova, size, false);

}

EXPORT_SYMBOL_GPL(iommu_unmap_fast);



size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,

			 struct scatterlist *sg, unsigned int nents, int prot)

{

include/linux/iommu.h

+49 −1
Original line number Diff line number Diff line
@@ -167,6 +167,10 @@ struct iommu_resv_region { 
 * @map: map a physically contiguous memory region to an iommu domain

 * @unmap: unmap a physically contiguous memory region from an iommu domain

 * @map_sg: map a scatter-gather list of physically contiguous memory chunks

 * @flush_tlb_all: Synchronously flush all hardware TLBs for this domain

 * @tlb_range_add: Add a given iova range to the flush queue for this domain

 * @tlb_sync: Flush all queued ranges from the hardware TLBs and empty flush

 *            queue

 * to an iommu domain

 * @iova_to_phys: translate iova to physical address

 * @add_device: add device to iommu grouping
@@ -199,6 +203,10 @@ struct iommu_ops { 
		     size_t size);

	size_t (*map_sg)(struct iommu_domain *domain, unsigned long iova,

			 struct scatterlist *sg, unsigned int nents, int prot);

	void (*flush_iotlb_all)(struct iommu_domain *domain);

	void (*iotlb_range_add)(struct iommu_domain *domain,

				unsigned long iova, size_t size);

	void (*iotlb_sync)(struct iommu_domain *domain);

	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);

	int (*add_device)(struct device *dev);

	void (*remove_device)(struct device *dev);
@@ -287,6 +295,8 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova, 
		     phys_addr_t paddr, size_t size, int prot);

extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,

			  size_t size);

extern size_t iommu_unmap_fast(struct iommu_domain *domain,

			       unsigned long iova, size_t size);

extern size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,

				struct scatterlist *sg,unsigned int nents,

				int prot);
@@ -343,6 +353,25 @@ extern void iommu_domain_window_disable(struct iommu_domain *domain, u32 wnd_nr) 
extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,

			      unsigned long iova, int flags);



static inline void iommu_flush_tlb_all(struct iommu_domain *domain)

{

	if (domain->ops->flush_iotlb_all)

		domain->ops->flush_iotlb_all(domain);

}



static inline void iommu_tlb_range_add(struct iommu_domain *domain,

				       unsigned long iova, size_t size)

{

	if (domain->ops->iotlb_range_add)

		domain->ops->iotlb_range_add(domain, iova, size);

}



static inline void iommu_tlb_sync(struct iommu_domain *domain)

{

	if (domain->ops->iotlb_sync)

		domain->ops->iotlb_sync(domain);

}



static inline size_t iommu_map_sg(struct iommu_domain *domain,

				  unsigned long iova, struct scatterlist *sg,

				  unsigned int nents, int prot)
@@ -436,6 +465,12 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova, 
	return -ENODEV;

}



static inline int iommu_unmap_fast(struct iommu_domain *domain, unsigned long iova,

				   int gfp_order)

{

	return -ENODEV;

}



static inline size_t iommu_map_sg(struct iommu_domain *domain,

				  unsigned long iova, struct scatterlist *sg,

				  unsigned int nents, int prot)
@@ -443,6 +478,19 @@ static inline size_t iommu_map_sg(struct iommu_domain *domain, 
	return -ENODEV;

}



static inline void iommu_flush_tlb_all(struct iommu_domain *domain)

{

}



static inline void iommu_tlb_range_add(struct iommu_domain *domain,

				       unsigned long iova, size_t size)

{

}



static inline void iommu_tlb_sync(struct iommu_domain *domain)

{

}



static inline int iommu_domain_window_enable(struct iommu_domain *domain,

					     u32 wnd_nr, phys_addr_t paddr,

					     u64 size, int prot)