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Message-ID: <20191209225344.99740-8-jhubbard@nvidia.com>
Date: Mon, 9 Dec 2019 14:53:25 -0800
From: John Hubbard <jhubbard@...dia.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: Al Viro <viro@...iv.linux.org.uk>,
Alex Williamson <alex.williamson@...hat.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Björn Töpel <bjorn.topel@...el.com>,
Christoph Hellwig <hch@...radead.org>,
Dan Williams <dan.j.williams@...el.com>,
Daniel Vetter <daniel@...ll.ch>,
Dave Chinner <david@...morbit.com>,
David Airlie <airlied@...ux.ie>,
"David S . Miller" <davem@...emloft.net>,
Ira Weiny <ira.weiny@...el.com>, Jan Kara <jack@...e.cz>,
Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>,
Jonathan Corbet <corbet@....net>,
Jérôme Glisse <jglisse@...hat.com>,
Magnus Karlsson <magnus.karlsson@...el.com>,
"Mauro Carvalho Chehab" <mchehab@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
Michal Hocko <mhocko@...e.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
"Paul Mackerras" <paulus@...ba.org>, Shuah Khan <shuah@...nel.org>,
Vlastimil Babka <vbabka@...e.cz>, <bpf@...r.kernel.org>,
<dri-devel@...ts.freedesktop.org>, <kvm@...r.kernel.org>,
<linux-block@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-fsdevel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
<linux-media@...r.kernel.org>, <linux-rdma@...r.kernel.org>,
<linuxppc-dev@...ts.ozlabs.org>, <netdev@...r.kernel.org>,
<linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
John Hubbard <jhubbard@...dia.com>,
"Jason Gunthorpe" <jgg@...lanox.com>
Subject: [PATCH v8 07/26] vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call
Update VFIO to take advantage of the recently loosened restriction on
FOLL_LONGTERM with get_user_pages_remote(). Also, now it is possible to
fix a bug: the VFIO caller is logically a FOLL_LONGTERM user, but it
wasn't setting FOLL_LONGTERM.
Also, remove an unnessary pair of calls that were releasing and
reacquiring the mmap_sem. There is no need to avoid holding mmap_sem
just in order to call page_to_pfn().
Also, now that the the DAX check ("if a VMA is DAX, don't allow long
term pinning") is in the internals of get_user_pages_remote() and
__gup_longterm_locked(), there's no need for it at the VFIO call site.
So remove it.
Tested-by: Alex Williamson <alex.williamson@...hat.com>
Acked-by: Alex Williamson <alex.williamson@...hat.com>
Reviewed-by: Jason Gunthorpe <jgg@...lanox.com>
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
Suggested-by: Jason Gunthorpe <jgg@...pe.ca>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Jerome Glisse <jglisse@...hat.com>
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
drivers/vfio/vfio_iommu_type1.c | 30 +++++-------------------------
1 file changed, 5 insertions(+), 25 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 2ada8e6cdb88..b800fc9a0251 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -322,7 +322,6 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
{
struct page *page[1];
struct vm_area_struct *vma;
- struct vm_area_struct *vmas[1];
unsigned int flags = 0;
int ret;
@@ -330,33 +329,14 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
flags |= FOLL_WRITE;
down_read(&mm->mmap_sem);
- if (mm == current->mm) {
- ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
- vmas);
- } else {
- ret = get_user_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
- * lead to indefinite stalls in filesystem operations.
- * Disallow attempts to pin fs-dax pages via this
- * interface.
- */
- if (ret > 0 && vma_is_fsdax(vmas[0])) {
- ret = -EOPNOTSUPP;
- put_page(page[0]);
- }
- }
- up_read(&mm->mmap_sem);
-
+ ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM,
+ page, NULL, NULL);
if (ret == 1) {
*pfn = page_to_pfn(page[0]);
- return 0;
+ ret = 0;
+ goto done;
}
- down_read(&mm->mmap_sem);
-
vaddr = untagged_addr(vaddr);
vma = find_vma_intersection(mm, vaddr, vaddr + 1);
@@ -366,7 +346,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
if (is_invalid_reserved_pfn(*pfn))
ret = 0;
}
-
+done:
up_read(&mm->mmap_sem);
return ret;
}
--
2.24.0
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