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mm/hmm: cleanup special vma handling (VM_SPECIAL)

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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>
This commit is contained in:
Jérôme Glisse 2018-04-10 16:28:42 -07:00 committed by Linus Torvalds
parent ff05c0c6bb
commit 855ce7d252
1 changed files with 20 additions and 20 deletions
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40
mm/hmm.c
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@ -324,14 +324,6 @@ static int hmm_vma_do_fault(struct mm_walk *walk,
return -EAGAIN;
}
static void hmm_pfns_special(uint64_t *pfns,
unsigned long addr,
unsigned long end)
{
for (; addr < end; addr += PAGE_SIZE, pfns++)
*pfns = HMM_PFN_SPECIAL;
}
static int hmm_pfns_bad(unsigned long addr,
unsigned long end,
struct mm_walk *walk)
@ -529,6 +521,14 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
return 0;
}
static void hmm_pfns_special(struct hmm_range *range)
{
unsigned long addr = range->start, i = 0;
for (; addr < range->end; addr += PAGE_SIZE, i++)
range->pfns[i] = HMM_PFN_SPECIAL;
}
/*
* hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses
* @range: range being snapshotted
@ -553,12 +553,6 @@ int hmm_vma_get_pfns(struct hmm_range *range)
struct mm_walk mm_walk;
struct hmm *hmm;
/* FIXME support hugetlb fs */
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
hmm_pfns_special(range->pfns, range->start, range->end);
return -EINVAL;
}
/* Sanity check, this really should not happen ! */
if (range->start < vma->vm_start || range->start >= vma->vm_end)
return -EINVAL;
@ -572,6 +566,12 @@ int hmm_vma_get_pfns(struct hmm_range *range)
if (!hmm->mmu_notifier.ops)
return -EINVAL;
/* FIXME support hugetlb fs */
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
hmm_pfns_special(range);
return -EINVAL;
}
if (!(vma->vm_flags & VM_READ)) {
/*
* If vma do not allow read access, then assume that it does
@ -740,6 +740,12 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block)
if (!hmm->mmu_notifier.ops)
return -EINVAL;
/* FIXME support hugetlb fs */
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
hmm_pfns_special(range);
return -EINVAL;
}
if (!(vma->vm_flags & VM_READ)) {
/*
* If vma do not allow read access, then assume that it does
@ -751,12 +757,6 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block)
return -EPERM;
}
/* FIXME support hugetlb fs */
if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) {
hmm_pfns_special(range->pfns, range->start, range->end);
return 0;
}
/* Initialize range to track CPU page table update */
spin_lock(&hmm->lock);
range->valid = true;