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| author | Alex Williamson <alex.williamson@redhat.com> | 2024-03-01 01:35:40 +0300 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2024-03-05 02:11:07 +0300 |
| commit | 5b992412776cdf2ec88b5b5138112e6b36e47995 (patch) | |
| tree | 0f42d6ffbf689dbac9fcbe555627ab437264ff54 /drivers/vfio | |
| parent | 81617c17bf58f008a57da74b97e60a0bf8e971fd (diff) | |
| download | linux-5b992412776cdf2ec88b5b5138112e6b36e47995.tar.xz | |
Revert "vfio/type1: Unpin zero pages"
This reverts commit 873aefb376bbc0ed1dd2381ea1d6ec88106fdbd4.
This was a heinous workaround and it turns out it's been fixed in mm
twice since it was introduced. Most recently, commit c8070b787519
("mm: Don't pin ZERO_PAGE in pin_user_pages()") would have prevented
running up the zeropage refcount, but even before that commit
84209e87c696 ("mm/gup: reliable R/O long-term pinning in COW mappings")
avoids the vfio use case from pinning the zeropage at all, instead
replacing it with exclusive anonymous pages.
Remove this now useless overhead.
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20240229223544.257207-1-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index b2854d7939ce..b5c15fe8f9fc 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -567,18 +567,6 @@ static int vaddr_get_pfns(struct mm_struct *mm, unsigned long vaddr, ret = pin_user_pages_remote(mm, vaddr, npages, flags | FOLL_LONGTERM, pages, NULL); if (ret > 0) { - int i; - - /* - * The zero page is always resident, we don't need to pin it - * and it falls into our invalid/reserved test so we don't - * unpin in put_pfn(). Unpin all zero pages in the batch here. - */ - for (i = 0 ; i < ret; i++) { - if (unlikely(is_zero_pfn(page_to_pfn(pages[i])))) - unpin_user_page(pages[i]); - } - *pfn = page_to_pfn(pages[0]); goto done; } |