mm/hmm: cleanup special vma handling (VM_SPECIAL)
Special vma (one with any of the VM_SPECIAL flags) can not be access by device because there is no consistent model across device drivers on those vma and their backing memory. This patch directly use hmm_range struct for hmm_pfns_special() argument as it is always affecting the whole vma and thus the whole range. It also make behavior consistent after this patch both hmm_vma_fault() and hmm_vma_get_pfns() returns -EINVAL when facing such vma. Previously hmm_vma_fault() returned 0 and hmm_vma_get_pfns() return -EINVAL but both were filling the HMM pfn array with special entry. Link: http://lkml.kernel.org/r/20180323005527.758-10-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Evgeny Baskakov <ebaskakov@nvidia.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Mark Hairgrove <mhairgrove@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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mm/hmm.c
40
mm/hmm.c
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@ -324,14 +324,6 @@ static int hmm_vma_do_fault(struct mm_walk *walk,
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return -EAGAIN;
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}
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static void hmm_pfns_special(uint64_t *pfns,
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unsigned long addr,
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unsigned long end)
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{
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for (; addr < end; addr += PAGE_SIZE, pfns++)
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*pfns = HMM_PFN_SPECIAL;
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}
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static int hmm_pfns_bad(unsigned long addr,
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unsigned long end,
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struct mm_walk *walk)
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@ -529,6 +521,14 @@ fault:
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return 0;
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}
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static void hmm_pfns_special(struct hmm_range *range)
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{
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unsigned long addr = range->start, i = 0;
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for (; addr < range->end; addr += PAGE_SIZE, i++)
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range->pfns[i] = HMM_PFN_SPECIAL;
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}
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/*
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* hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses
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* @range: range being snapshotted
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@ -553,12 +553,6 @@ int hmm_vma_get_pfns(struct hmm_range *range)
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struct mm_walk mm_walk;
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struct hmm *hmm;
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/* FIXME support hugetlb fs */
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if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
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hmm_pfns_special(range->pfns, range->start, range->end);
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return -EINVAL;
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}
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/* Sanity check, this really should not happen ! */
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if (range->start < vma->vm_start || range->start >= vma->vm_end)
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return -EINVAL;
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@ -572,6 +566,12 @@ int hmm_vma_get_pfns(struct hmm_range *range)
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if (!hmm->mmu_notifier.ops)
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return -EINVAL;
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/* FIXME support hugetlb fs */
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if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
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hmm_pfns_special(range);
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return -EINVAL;
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}
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if (!(vma->vm_flags & VM_READ)) {
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/*
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* If vma do not allow read access, then assume that it does
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@ -740,6 +740,12 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block)
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if (!hmm->mmu_notifier.ops)
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return -EINVAL;
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/* FIXME support hugetlb fs */
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if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
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hmm_pfns_special(range);
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return -EINVAL;
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}
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if (!(vma->vm_flags & VM_READ)) {
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/*
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* If vma do not allow read access, then assume that it does
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@ -751,12 +757,6 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block)
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return -EPERM;
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}
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/* FIXME support hugetlb fs */
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if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
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hmm_pfns_special(range->pfns, range->start, range->end);
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return 0;
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}
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/* Initialize range to track CPU page table update */
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spin_lock(&hmm->lock);
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range->valid = true;
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