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iommu/vt-d: change intel-iommu to use IOVA frame numbers
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Make intel-iommu map/unmap/invalidate work with IOVA pfns instead of
pointers to "struct iova". This avoids using the iova struct from the IOVA
red-black tree and the resulting explicit find_iova() on unmap.

This patch will allow us to cache IOVAs in the next patch, in order to
avoid rbtree operations for the majority of map/unmap operations.

Note: In eliminating the find_iova() operation, we have also eliminated
the sanity check previously done in the unmap flow. Arguably, this was
overhead that is better avoided in production code, but it could be
brought back as a debug option for driver development.

Signed-off-by: Omer Peleg <omer@cs.technion.ac.il>
[mad@cs.technion.ac.il: rebased, fixed to not break iova api, and reworded
 the commit message]
Signed-off-by: Adam Morrison <mad@cs.technion.ac.il>
Reviewed-by: Shaohua Li <shli@fb.com>
Reviewed-by: Ben Serebrin <serebrin@google.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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Omer Peleg authored and David Woodhouse committed Apr 20, 2016
1 parent 0824c59 commit 2aac630
Showing 1 changed file with 29 additions and 32 deletions.
61 changes: 29 additions & 32 deletions drivers/iommu/intel-iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -459,7 +459,7 @@ static LIST_HEAD(dmar_rmrr_units);
static void flush_unmaps_timeout(unsigned long data);

struct deferred_flush_entry {
struct iova *iova;
unsigned long iova_pfn;
unsigned long nrpages;
struct dmar_domain *domain;
struct page *freelist;
Expand Down Expand Up @@ -3353,7 +3353,7 @@ static int __init init_dmars(void)
}

/* This takes a number of _MM_ pages, not VTD pages */
static struct iova *intel_alloc_iova(struct device *dev,
static unsigned long intel_alloc_iova(struct device *dev,
struct dmar_domain *domain,
unsigned long nrpages, uint64_t dma_mask)
{
Expand All @@ -3373,16 +3373,16 @@ static struct iova *intel_alloc_iova(struct device *dev,
iova = alloc_iova(&domain->iovad, nrpages,
IOVA_PFN(DMA_BIT_MASK(32)), 1);
if (iova)
return iova;
return iova->pfn_lo;
}
iova = alloc_iova(&domain->iovad, nrpages, IOVA_PFN(dma_mask), 1);
if (unlikely(!iova)) {
pr_err("Allocating %ld-page iova for %s failed",
nrpages, dev_name(dev));
return NULL;
return 0;
}

return iova;
return iova->pfn_lo;
}

static struct dmar_domain *__get_valid_domain_for_dev(struct device *dev)
Expand Down Expand Up @@ -3480,7 +3480,7 @@ static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
{
struct dmar_domain *domain;
phys_addr_t start_paddr;
struct iova *iova;
unsigned long iova_pfn;
int prot = 0;
int ret;
struct intel_iommu *iommu;
Expand All @@ -3498,8 +3498,8 @@ static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
iommu = domain_get_iommu(domain);
size = aligned_nrpages(paddr, size);

iova = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size), dma_mask);
if (!iova)
iova_pfn = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size), dma_mask);
if (!iova_pfn)
goto error;

/*
Expand All @@ -3517,26 +3517,26 @@ static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
* might have two guest_addr mapping to the same host paddr, but this
* is not a big problem
*/
ret = domain_pfn_mapping(domain, mm_to_dma_pfn(iova->pfn_lo),
ret = domain_pfn_mapping(domain, mm_to_dma_pfn(iova_pfn),
mm_to_dma_pfn(paddr_pfn), size, prot);
if (ret)
goto error;

/* it's a non-present to present mapping. Only flush if caching mode */
if (cap_caching_mode(iommu->cap))
iommu_flush_iotlb_psi(iommu, domain,
mm_to_dma_pfn(iova->pfn_lo),
mm_to_dma_pfn(iova_pfn),
size, 0, 1);
else
iommu_flush_write_buffer(iommu);

start_paddr = (phys_addr_t)iova->pfn_lo << PAGE_SHIFT;
start_paddr = (phys_addr_t)iova_pfn << PAGE_SHIFT;
start_paddr += paddr & ~PAGE_MASK;
return start_paddr;

error:
if (iova)
__free_iova(&domain->iovad, iova);
if (iova_pfn)
free_iova(&domain->iovad, iova_pfn);
pr_err("Device %s request: %zx@%llx dir %d --- failed\n",
dev_name(dev), size, (unsigned long long)paddr, dir);
return 0;
Expand Down Expand Up @@ -3576,22 +3576,22 @@ static void flush_unmaps(struct deferred_flush_data *flush_data)
unsigned long mask;
struct deferred_flush_entry *entry =
&flush_table->entries[j];
struct iova *iova = entry->iova;
unsigned long iova_pfn = entry->iova_pfn;
unsigned long nrpages = entry->nrpages;
struct dmar_domain *domain = entry->domain;
struct page *freelist = entry->freelist;

/* On real hardware multiple invalidations are expensive */
if (cap_caching_mode(iommu->cap))
iommu_flush_iotlb_psi(iommu, domain,
mm_to_dma_pfn(iova->pfn_lo),
mm_to_dma_pfn(iova_pfn),
nrpages, !freelist, 0);
else {
mask = ilog2(nrpages);
iommu_flush_dev_iotlb(domain,
(uint64_t)iova->pfn_lo << PAGE_SHIFT, mask);
(uint64_t)iova_pfn << PAGE_SHIFT, mask);
}
__free_iova(&domain->iovad, iova);
free_iova(&domain->iovad, iova_pfn);
if (freelist)
dma_free_pagelist(freelist);
}
Expand All @@ -3611,7 +3611,7 @@ static void flush_unmaps_timeout(unsigned long cpuid)
spin_unlock_irqrestore(&flush_data->lock, flags);
}

static void add_unmap(struct dmar_domain *dom, struct iova *iova,
static void add_unmap(struct dmar_domain *dom, unsigned long iova_pfn,
unsigned long nrpages, struct page *freelist)
{
unsigned long flags;
Expand Down Expand Up @@ -3645,7 +3645,7 @@ static void add_unmap(struct dmar_domain *dom, struct iova *iova,

entry = &flush_data->tables[iommu_id].entries[entry_id];
entry->domain = dom;
entry->iova = iova;
entry->iova_pfn = iova_pfn;
entry->nrpages = nrpages;
entry->freelist = freelist;

Expand All @@ -3664,7 +3664,7 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
struct dmar_domain *domain;
unsigned long start_pfn, last_pfn;
unsigned long nrpages;
struct iova *iova;
unsigned long iova_pfn;
struct intel_iommu *iommu;
struct page *freelist;

Expand All @@ -3676,13 +3676,10 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)

iommu = domain_get_iommu(domain);

iova = find_iova(&domain->iovad, IOVA_PFN(dev_addr));
if (WARN_ONCE(!iova, "Driver unmaps unmatched page at PFN %llx\n",
(unsigned long long)dev_addr))
return;
iova_pfn = IOVA_PFN(dev_addr);

nrpages = aligned_nrpages(dev_addr, size);
start_pfn = mm_to_dma_pfn(iova->pfn_lo);
start_pfn = mm_to_dma_pfn(iova_pfn);
last_pfn = start_pfn + nrpages - 1;

pr_debug("Device %s unmapping: pfn %lx-%lx\n",
Expand All @@ -3694,10 +3691,10 @@ static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
iommu_flush_iotlb_psi(iommu, domain, start_pfn,
nrpages, !freelist, 0);
/* free iova */
__free_iova(&domain->iovad, iova);
free_iova(&domain->iovad, iova_pfn);
dma_free_pagelist(freelist);
} else {
add_unmap(domain, iova, nrpages, freelist);
add_unmap(domain, iova_pfn, nrpages, freelist);
/*
* queue up the release of the unmap to save the 1/6th of the
* cpu used up by the iotlb flush operation...
Expand Down Expand Up @@ -3810,7 +3807,7 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
struct dmar_domain *domain;
size_t size = 0;
int prot = 0;
struct iova *iova = NULL;
unsigned long iova_pfn;
int ret;
struct scatterlist *sg;
unsigned long start_vpfn;
Expand All @@ -3829,9 +3826,9 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
for_each_sg(sglist, sg, nelems, i)
size += aligned_nrpages(sg->offset, sg->length);

iova = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size),
iova_pfn = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size),
*dev->dma_mask);
if (!iova) {
if (!iova_pfn) {
sglist->dma_length = 0;
return 0;
}
Expand All @@ -3846,13 +3843,13 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
prot |= DMA_PTE_WRITE;

start_vpfn = mm_to_dma_pfn(iova->pfn_lo);
start_vpfn = mm_to_dma_pfn(iova_pfn);

ret = domain_sg_mapping(domain, start_vpfn, sglist, size, prot);
if (unlikely(ret)) {
dma_pte_free_pagetable(domain, start_vpfn,
start_vpfn + size - 1);
__free_iova(&domain->iovad, iova);
free_iova(&domain->iovad, iova_pfn);
return 0;
}

Expand Down

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