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vfio/type1: Adopt fast IOTLB flush interface when unmap IOVAs

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VFIO IOMMU type1 currently upmaps IOVA pages synchronously, which requires
IOTLB flushing for every unmapping. This results in large IOTLB flushing
overhead when handling pass-through devices has a large number of mapped
IOVAs. This can be avoided by using the new IOTLB flushing interface.

Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
[aw - use LIST_HEAD]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Suravee Suthikulpanit 2018-03-21 12:46:19 -06:00 committed by Alex Williamson
parent c698ca5278
commit 6bd06f5a48
1 changed files with 115 additions and 11 deletions
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122
drivers/vfio/vfio_iommu_type1.c
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@ -102,6 +102,13 @@ struct vfio_pfn {
atomic_t ref_count;
};
struct vfio_regions {
struct list_head list;
dma_addr_t iova;
phys_addr_t phys;
size_t len;
};
#define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \
(!list_empty(&iommu->domain_list))
@ -660,11 +667,102 @@ unpin_exit:
return i > npage ? npage : (i > 0 ? i : -EINVAL);
}
static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,
struct list_head *regions)
{
long unlocked = 0;
struct vfio_regions *entry, *next;
iommu_tlb_sync(domain->domain);
list_for_each_entry_safe(entry, next, regions, list) {
unlocked += vfio_unpin_pages_remote(dma,
entry->iova,
entry->phys >> PAGE_SHIFT,
entry->len >> PAGE_SHIFT,
false);
list_del(&entry->list);
kfree(entry);
}
cond_resched();
return unlocked;
}
/*
* Generally, VFIO needs to unpin remote pages after each IOTLB flush.
* Therefore, when using IOTLB flush sync interface, VFIO need to keep track
* of these regions (currently using a list).
*
* This value specifies maximum number of regions for each IOTLB flush sync.
*/
#define VFIO_IOMMU_TLB_SYNC_MAX 512
static size_t unmap_unpin_fast(struct vfio_domain *domain,
struct vfio_dma *dma, dma_addr_t *iova,
size_t len, phys_addr_t phys, long *unlocked,
struct list_head *unmapped_list,
int *unmapped_cnt)
{
size_t unmapped = 0;
struct vfio_regions *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (entry) {
unmapped = iommu_unmap_fast(domain->domain, *iova, len);
if (!unmapped) {
kfree(entry);
} else {
iommu_tlb_range_add(domain->domain, *iova, unmapped);
entry->iova = *iova;
entry->phys = phys;
entry->len = unmapped;
list_add_tail(&entry->list, unmapped_list);
*iova += unmapped;
(*unmapped_cnt)++;
}
}
/*
* Sync if the number of fast-unmap regions hits the limit
* or in case of errors.
*/
if (*unmapped_cnt >= VFIO_IOMMU_TLB_SYNC_MAX || !unmapped) {
*unlocked += vfio_sync_unpin(dma, domain,
unmapped_list);
*unmapped_cnt = 0;
}
return unmapped;
}
static size_t unmap_unpin_slow(struct vfio_domain *domain,
struct vfio_dma *dma, dma_addr_t *iova,
size_t len, phys_addr_t phys,
long *unlocked)
{
size_t unmapped = iommu_unmap(domain->domain, *iova, len);
if (unmapped) {
*unlocked += vfio_unpin_pages_remote(dma, *iova,
phys >> PAGE_SHIFT,
unmapped >> PAGE_SHIFT,
false);
*iova += unmapped;
cond_resched();
}
return unmapped;
}
static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
bool do_accounting)
{
dma_addr_t iova = dma->iova, end = dma->iova + dma->size;
struct vfio_domain *domain, *d;
LIST_HEAD(unmapped_region_list);
int unmapped_region_cnt = 0;
long unlocked = 0;
if (!dma->size)
@ -710,20 +808,26 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
break;
}
unmapped = iommu_unmap(domain->domain, iova, len);
/*
* First, try to use fast unmap/unpin. In case of failure,
* switch to slow unmap/unpin path.
*/
unmapped = unmap_unpin_fast(domain, dma, &iova, len, phys,
&unlocked, &unmapped_region_list,
&unmapped_region_cnt);
if (!unmapped) {
unmapped = unmap_unpin_slow(domain, dma, &iova, len,
phys, &unlocked);
if (WARN_ON(!unmapped))
break;
unlocked += vfio_unpin_pages_remote(dma, iova,
phys >> PAGE_SHIFT,
unmapped >> PAGE_SHIFT,
false);
iova += unmapped;
cond_resched();
}
}
dma->iommu_mapped = false;
if (unmapped_region_cnt)
unlocked += vfio_sync_unpin(dma, domain, &unmapped_region_list);
if (do_accounting) {
vfio_lock_acct(dma->task, -unlocked, NULL);
return 0;