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xen/gntdev.c: Mark pages as dirty

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There seems to be a bug in the original code when gntdev_get_page()
is called with writeable=true then the page needs to be marked dirty
before being put.

To address this, a bool writeable is added in gnt_dev_copy_batch, set
it in gntdev_grant_copy_seg() (and drop `writeable` argument to
gntdev_get_page()) and then, based on batch->writeable, use
set_page_dirty_lock().

Fixes: a4cdb556cae0 (xen/gntdev: add ioctl for grant copy)
Suggested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1599375114-32360-1-git-send-email-jrdr.linux@gmail.com
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Souptick Joarder 2020-09-06 12:21:53 +05:30 committed by Boris Ostrovsky
parent 549738f15d
commit 779055842d
1 changed files with 12 additions and 5 deletions
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17
drivers/xen/gntdev.c
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@ -720,17 +720,18 @@ struct gntdev_copy_batch {
s16 __user *status[GNTDEV_COPY_BATCH];
unsigned int nr_ops;
unsigned int nr_pages;
bool writeable;
};
static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
bool writeable, unsigned long *gfn)
unsigned long *gfn)
{
unsigned long addr = (unsigned long)virt;
struct page *page;
unsigned long xen_pfn;
int ret;
ret = get_user_pages_fast(addr, 1, writeable ? FOLL_WRITE : 0, &page);
ret = get_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page);
if (ret < 0)
return ret;
@ -746,9 +747,13 @@ static void gntdev_put_pages(struct gntdev_copy_batch *batch)
{
unsigned int i;
for (i = 0; i < batch->nr_pages; i++)
for (i = 0; i < batch->nr_pages; i++) {
if (batch->writeable && !PageDirty(batch->pages[i]))
set_page_dirty_lock(batch->pages[i]);
put_page(batch->pages[i]);
}
batch->nr_pages = 0;
batch->writeable = false;
}
static int gntdev_copy(struct gntdev_copy_batch *batch)
@ -837,8 +842,9 @@ static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
virt = seg->source.virt + copied;
off = (unsigned long)virt & ~XEN_PAGE_MASK;
len = min(len, (size_t)XEN_PAGE_SIZE - off);
batch->writeable = false;
ret = gntdev_get_page(batch, virt, false, &gfn);
ret = gntdev_get_page(batch, virt, &gfn);
if (ret < 0)
return ret;
@ -856,8 +862,9 @@ static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
virt = seg->dest.virt + copied;
off = (unsigned long)virt & ~XEN_PAGE_MASK;
len = min(len, (size_t)XEN_PAGE_SIZE - off);
batch->writeable = true;
ret = gntdev_get_page(batch, virt, true, &gfn);
ret = gntdev_get_page(batch, virt, &gfn);
if (ret < 0)
return ret;