Commit 77905584 authored by Souptick Joarder's avatar Souptick Joarder Committed by Boris Ostrovsky
Browse files

xen/gntdev.c: Mark pages as dirty 



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: a4cdb556 (xen/gntdev: add ioctl for grant copy)
Suggested-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarSouptick 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: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 549738f1

drivers/xen/gntdev.c

+12 −5
Original line number Diff line number Diff line
@@ -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;

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