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author | 2018-03-22 12:52:16 +0800 | |
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committer | 2018-03-22 13:18:27 -0600 | |
commit | 356e88ebe4473a3663cf3d14727ce293a4526d34 (patch) | |
tree | e261e27c7ed605750677e610ae7d66dec2d1157c /drivers/vfio/vfio_iommu_type1.c | |
parent | vfio-mdev/samples: change RDI interrupt condition (diff) | |
download | linux-356e88ebe4473a3663cf3d14727ce293a4526d34.tar.gz linux-356e88ebe4473a3663cf3d14727ce293a4526d34.tar.bz2 linux-356e88ebe4473a3663cf3d14727ce293a4526d34.zip |
vfio/type1: Improve memory pinning process for raw PFN mapping
When using vfio to pass through a PCIe device (e.g. a GPU card) that
has a huge BAR (e.g. 16GB), a lot of cycles are wasted on memory
pinning because PFNs of PCI BAR are not backed by struct page, and
the corresponding VMA has flag VM_PFNMAP.
With this change, when pinning a region which is a raw PFN mapping,
it can skip unnecessary user memory pinning process, and thus, can
significantly improve VM's boot up time when passing through devices
via VFIO. In my test on a Xeon E5 2.6GHz, the time mapping a 16GB
BAR was reduced from about 0.4s to 1.5us.
Signed-off-by: Jason Cai (Xiang Feng) <jason.cai@linux.alibaba.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio/vfio_iommu_type1.c')
-rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 3c082451ab1a..5c212bf29640 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -404,7 +404,6 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, { unsigned long pfn = 0; long ret, pinned = 0, lock_acct = 0; - bool rsvd; dma_addr_t iova = vaddr - dma->vaddr + dma->iova; /* This code path is only user initiated */ @@ -415,14 +414,23 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, if (ret) return ret; + if (is_invalid_reserved_pfn(*pfn_base)) { + struct vm_area_struct *vma; + + down_read(¤t->mm->mmap_sem); + vma = find_vma_intersection(current->mm, vaddr, vaddr + 1); + pinned = min_t(long, npage, vma_pages(vma)); + up_read(¤t->mm->mmap_sem); + return pinned; + } + pinned++; - rsvd = is_invalid_reserved_pfn(*pfn_base); /* * Reserved pages aren't counted against the user, externally pinned * pages are already counted against the user. */ - if (!rsvd && !vfio_find_vpfn(dma, iova)) { + if (!vfio_find_vpfn(dma, iova)) { if (!lock_cap && current->mm->locked_vm + 1 > limit) { put_pfn(*pfn_base, dma->prot); pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__, @@ -442,13 +450,12 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, if (ret) break; - if (pfn != *pfn_base + pinned || - rsvd != is_invalid_reserved_pfn(pfn)) { + if (pfn != *pfn_base + pinned) { put_pfn(pfn, dma->prot); break; } - if (!rsvd && !vfio_find_vpfn(dma, iova)) { + if (!vfio_find_vpfn(dma, iova)) { if (!lock_cap && current->mm->locked_vm + lock_acct + 1 > limit) { put_pfn(pfn, dma->prot); @@ -466,10 +473,8 @@ out: unpin_out: if (ret) { - if (!rsvd) { - for (pfn = *pfn_base ; pinned ; pfn++, pinned--) - put_pfn(pfn, dma->prot); - } + for (pfn = *pfn_base ; pinned ; pfn++, pinned--) + put_pfn(pfn, dma->prot); return ret; } |