From owner-svn-src-all@FreeBSD.ORG  Sat Jul 26 02:51:46 2014
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id BDA63910;
 Sat, 26 Jul 2014 02:51:46 +0000 (UTC)
Received: from svn.freebsd.org (svn.freebsd.org
 [IPv6:2001:1900:2254:2068::e6a:0])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id AABFC2902;
 Sat, 26 Jul 2014 02:51:46 +0000 (UTC)
Received: from svn.freebsd.org ([127.0.1.70])
 by svn.freebsd.org (8.14.8/8.14.8) with ESMTP id s6Q2pknA030375;
 Sat, 26 Jul 2014 02:51:46 GMT (envelope-from neel@svn.freebsd.org)
Received: (from neel@localhost)
 by svn.freebsd.org (8.14.8/8.14.8/Submit) id s6Q2pktD030374;
 Sat, 26 Jul 2014 02:51:46 GMT (envelope-from neel@svn.freebsd.org)
Message-Id: <201407260251.s6Q2pktD030374@svn.freebsd.org>
From: Neel Natu <neel@FreeBSD.org>
Date: Sat, 26 Jul 2014 02:51:46 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r269108 - head/sys/amd64/vmm
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
 user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all/>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 26 Jul 2014 02:51:46 -0000

Author: neel
Date: Sat Jul 26 02:51:46 2014
New Revision: 269108
URL: http://svnweb.freebsd.org/changeset/base/269108

Log:
  Don't return -1 from the push emulation handler. Negative return values are
  interpreted specially on return from sys_ioctl() and may cause undesirable
  side-effects like restarting the system call.

Modified:
  head/sys/amd64/vmm/vmm_instruction_emul.c

Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c	Sat Jul 26 02:41:18 2014	(r269107)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c	Sat Jul 26 02:51:46 2014	(r269108)
@@ -781,10 +781,17 @@ emulate_push(void *vm, int vcpuid, uint6
 
 	error = vm_copy_setup(vm, vcpuid, paging, stack_gla, size, PROT_WRITE,
 	    copyinfo, nitems(copyinfo));
-	if (error == -1)
-		return (-1);	/* Unrecoverable error */
-	else if (error == 1)
-		return (0);	/* Return to guest to handle page fault */
+	if (error == -1) {
+		/*
+		 * XXX cannot return a negative error value here because it
+		 * ends up being the return value of the VM_RUN() ioctl and
+		 * is interpreted as a pseudo-error (for e.g. ERESTART).
+		 */
+		return (EFAULT);
+	} else if (error == 1) {
+		/* Resume guest execution to handle page fault */
+		return (0);
+	}
 
 	error = memread(vm, vcpuid, mmio_gpa, &val, size, arg);
 	if (error == 0) {