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authorAlex Williamson <alex.williamson@redhat.com>2024-02-29 23:35:40 +0100
committerAlex Williamson <alex.williamson@redhat.com>2024-03-05 00:11:07 +0100
commit5b992412776cdf2ec88b5b5138112e6b36e47995 (patch)
tree0f42d6ffbf689dbac9fcbe555627ab437264ff54 /drivers/vfio
parentvfio/nvgrace-gpu: Convey kvm to map device memory region as noncached (diff)
downloadlinux-5b992412776cdf2ec88b5b5138112e6b36e47995.tar.xz
linux-5b992412776cdf2ec88b5b5138112e6b36e47995.zip
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.c12
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;
}