From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:54225)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <Stefano.Stabellini@citrix.com>) id 1W09D0-0001Ba-Px
	for qemu-devel@nongnu.org; Mon, 06 Jan 2014 07:23:11 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <Stefano.Stabellini@citrix.com>) id 1W09Cv-0002nd-Mq
	for qemu-devel@nongnu.org; Mon, 06 Jan 2014 07:23:06 -0500
Received: from smtp.citrix.com ([66.165.176.89]:26514)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <Stefano.Stabellini@citrix.com>) id 1W09Cv-0002nP-I9
	for qemu-devel@nongnu.org; Mon, 06 Jan 2014 07:23:01 -0500
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Mon, 6 Jan 2014 12:22:05 +0000
Message-ID: <1389010925-22832-1-git-send-email-stefano.stabellini@eu.citrix.com>
MIME-Version: 1.0
Content-Type: text/plain
Subject: [Qemu-devel] [PATCH] xenfb: map framebuffer read-only and handle
	unmap errors
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: xen-devel@lists.xensource.com
Cc: stefano.stabellini@eu.citrix.com, phcoder@gmail.com, qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, Anthony Liguori <anthony@codemonkey.ws>, Paolo Bonzini <pbonzini@redhat.com>

The framebuffer is needlessly mapped (PROT_READ | PROT_WRITE), map it
PROT_READ instead.

The framebuffer is unmapped by replacing the framebuffer pages with
anonymous shared memory, calling mmap. Check for return errors and print
a warning.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Gerd Hoffmann <kraxel@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Anthony Liguori <anthony@codemonkey.ws>
CC: phcoder@gmail.com

diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index f0333a0..cb9d456 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -495,7 +495,7 @@ static int xenfb_map_fb(struct XenFB *xenfb)
     munmap(map, n_fbdirs * XC_PAGE_SIZE);
 
     xenfb->pixels = xc_map_foreign_pages(xen_xc, xenfb->c.xendev.dom,
-					 PROT_READ | PROT_WRITE, fbmfns, xenfb->fbpages);
+            PROT_READ, fbmfns, xenfb->fbpages);
     if (xenfb->pixels == NULL)
 	goto out;
 
@@ -903,6 +903,11 @@ static void fb_disconnect(struct XenDevice *xendev)
     fb->pixels = mmap(fb->pixels, fb->fbpages * XC_PAGE_SIZE,
                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON,
                       -1, 0);
+    if (fb->pixels == MAP_FAILED) {
+        xen_be_printf(xendev, 0,
+                "Couldn't replace the framebuffer with anonymous memory errno=%d\n",
+                errno);
+    }
     common_unbind(&fb->c);
     fb->feature_update = 0;
     fb->bug_trigger    = 0;