linux-kernel - [PATCH 4.4 33/90] xen/privcmd: Support correctly 64KB page granularity when mapping memory

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Message-Id: <20170612152558.198800742@linuxfoundation.org>
Date:   Mon, 12 Jun 2017 17:25:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Feng Kan <fkan@....com>,
        Julien Grall <julien.grall@....com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>
Subject: [PATCH 4.4 33/90] xen/privcmd: Support correctly 64KB page granularity when mapping memory

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Julien Grall <julien.grall@....com>

commit 753c09b5652bb4fe53e2db648002ec64b32b8827 upstream.

Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" did
not go far enough to support 64KB in mmap_batch_fn.

The variable 'nr' is the number of 4KB chunk to map. However, when Linux
is using 64KB page granularity the array of pages (vma->vm_private_data)
contain one page per 64KB. Fix it by incrementing st->index correctly.

Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
XEN_PAGE_SIZE.

Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page granularity")
Reported-by: Feng Kan <fkan@....com>
Signed-off-by: Julien Grall <julien.grall@....com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/xen/privcmd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -335,8 +335,8 @@ static int mmap_batch_fn(void *data, int
 				st->global_error = 1;
 		}
 	}
-	st->va += PAGE_SIZE * nr;
-	st->index += nr;
+	st->va += XEN_PAGE_SIZE * nr;
+	st->index += nr / XEN_PFN_PER_PAGE;
 
 	return 0;
 }