From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Hubbard Subject: [PATCH v2 14/18] vfio, mm: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion Date: Sun, 3 Nov 2019 13:18:09 -0800 Message-ID: <20191103211813.213227-15-jhubbard@nvidia.com> References: <20191103211813.213227-1-jhubbard@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20191103211813.213227-1-jhubbard@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman M List-Id: dri-devel@lists.freedesktop.org 1. Change vfio from get_user_pages(FOLL_LONGTERM), to pin_longterm_pages(), which sets both FOLL_LONGTERM and FOLL_PIN. 2. Because all FOLL_PIN-acquired pages must be released via put_user_page(), also convert the put_page() call over to put_user_pages(). Note that this effectively changes the code's behavior in vfio_iommu_type1.c: put_pfn(): it now ultimately calls set_page_dirty_lock(), instead of set_page_dirty(). This is probably more accurate. As Christoph Hellwig put it, "set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off." [1] [1] https://lore.kernel.org/r/20190723153640.GB720@lst.de Cc: Alex Williamson Signed-off-by: John Hubbard --- drivers/vfio/vfio_iommu_type1.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type= 1.c index d864277ea16f..795e13f3ef08 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -327,9 +327,8 @@ static int put_pfn(unsigned long pfn, int prot) { if (!is_invalid_reserved_pfn(pfn)) { struct page *page =3D pfn_to_page(pfn); - if (prot & IOMMU_WRITE) - SetPageDirty(page); - put_page(page); + + put_user_pages_dirty_lock(&page, 1, prot & IOMMU_WRITE); return 1; } return 0; @@ -349,11 +348,11 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsign= ed long vaddr, =20 down_read(&mm->mmap_sem); if (mm =3D=3D current->mm) { - ret =3D get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, - vmas); + ret =3D pin_longterm_pages(vaddr, 1, flags, page, vmas); } else { - ret =3D get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, - vmas, NULL); + ret =3D pin_longterm_pages_remote(NULL, mm, vaddr, 1, + flags, page, vmas, + NULL); /* * The lifetime of a vaddr_get_pfn() page pin is * userspace-controlled. In the fs-dax case this could @@ -363,7 +362,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned= long vaddr, */ if (ret > 0 && vma_is_fsdax(vmas[0])) { ret =3D -EOPNOTSUPP; - put_page(page[0]); + put_user_page(page[0]); } } up_read(&mm->mmap_sem); --=20 2.23.0