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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: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Joerg Roedel 2017-08-23 15:50:04 +02:00
parent 0688a09990
commit add02cfdc9
2 changed files with 77 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/iommu/iommu.c
View File

@ -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)
{

50
include/linux/iommu.h
View File

@ -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);
@ -286,7 +294,9 @@ extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
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);
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)