From 5b992412776cdf2ec88b5b5138112e6b36e47995 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Thu, 29 Feb 2024 15:35:40 -0700 Subject: 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 Reviewed-by: David Hildenbrand Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20240229223544.257207-1-alex.williamson@redhat.com Signed-off-by: Alex Williamson --- drivers/vfio/vfio_iommu_type1.c | 12 ------------ 1 file changed, 12 deletions(-) (limited to 'drivers/vfio') 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; } -- cgit v1.2.3