From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756170Ab2EXKvg (ORCPT ); Thu, 24 May 2012 06:51:36 -0400 Received: from smtp.ctxuk.citrix.com ([62.200.22.115]:41390 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755985Ab2EXKvb (ORCPT ); Thu, 24 May 2012 06:51:31 -0400 X-IronPort-AV: E=Sophos;i="4.75,649,1330905600"; d="scan'208";a="12646484" Date: Thu, 24 May 2012 11:51:14 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball-desktop To: Konrad Rzeszutek Wilk CC: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" Subject: Re: [PATCH 3/4] xen/hvc: Check HVM_PARAM_CONSOLE_[EVTCHN|PFN] for correctness. In-Reply-To: <1337795222-29946-4-git-send-email-konrad.wilk@oracle.com> Message-ID: References: <1337795222-29946-1-git-send-email-konrad.wilk@oracle.com> <1337795222-29946-4-git-send-email-konrad.wilk@oracle.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 23 May 2012, Konrad Rzeszutek Wilk wrote: > We need to make sure that those parameters are setup to be correct. > As such the value of 0 is deemed invalid and we find that we > bail out. The hypervisor sets by default all of them to be zero > and when the hypercall is done does a simple: > > a.value = d->arch.hvm_domain.params[a.index]; > > Which means that if the Xen toolstack forgot to setup the proper > HVM_PARAM_CONSOLE_EVTCHN, we would get the default value of 0 > and use that. I see, so the default value for v needs to be 0, because it's what the hypervisor would return anyway if the parameter hasn't been set. > CC: stable@kernel.org > Fixes-Oracle-Bug: 14091238 > Signed-off-by: Konrad Rzeszutek Wilk > --- > drivers/tty/hvc/hvc_xen.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c > index 3277f0e..5fb1cb9 100644 > --- a/drivers/tty/hvc/hvc_xen.c > +++ b/drivers/tty/hvc/hvc_xen.c > @@ -216,12 +216,12 @@ static int xen_hvm_console_init(void) > return 0; > > r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); > - if (r < 0) > + if (r < 0 || v == 0) > goto err; > info->evtchn = v; > v = 0; > r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v); > - if (r < 0) > + if (r < 0 || v == 0) > goto err; > mfn = v; > info->intf = ioremap(mfn << PAGE_SHIFT, PAGE_SIZE); I think that we should add a comment stating that even though mfn = 0 and evtchn = 0 are theoretically correct values, in practice they never are and they mean that a legacy toolstack hasn't initialized the pv console correctly.