From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Huang Subject: Re: [PATCH] x86: convert BUG_ON()s to WARN_ON()s in read_descriptor() Date: Fri, 16 Dec 2011 11:59:04 -0600 Message-ID: <4EEB86E8.3090004@amd.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "xen-devel@lists.xensource.com" , Jan Beulich List-Id: xen-devel@lists.xenproject.org Hi Keir, The public errata doc has been updated. You can find Erratum 700 info using the following steps: 1. Go to http://support.amd.com/us/psearch/Pages/psearch.aspx?type=2.7 2. Search with Product Type = "Processor", Product = "Any", Keyword = "Revision Guide". 3. Click on Technical Documents tab and 33610 is the one you are looking for. Hope this helps... -Wei On 12/16/2011 08:48 AM, Keir Fraser wrote: > On 16/12/2011 14:44, "Jan Beulich" wrote: > >>>>> On 16.12.11 at 10:09, Keir Fraser wrote: >>> On 15/12/2011 10:25, "Jan Beulich" wrote: >>> >>>> In the light of AMD erratum #700, and given that these checks happen >>>> for debugging purposes only and also only in debug builds of the >>>> hypervisor, make the failures non-fatal. >>> I think the changeset comment should have a brief description of erratum >>> #700. >> I'd do this, but ... >> >>> I also some reference should be made in a comment above the first >>> WARN_ON, explaining why they are now WARN_Ons (again, with reference to #700 >>> and its symptoms). >> ... I now think that these should never have been BUG_ON()s in the >> first place (despite probably having been the one who introduced >> them). >> >> Additionally, on a second look, check_descriptor() would not allow any >> of the affected selector types to be installed into a descriptor table, >> and we clearly don't put in any such descriptors ourselves, so from the >> perspective of the erratum we're okay without the patch. >> >> So if you prefer them to stay BUG_ON(), I think I'll just withdraw the >> patch. > If the erratum cannot affect us then they may as well stay as BUG_ON and we > sidestep the whole thing. > > -- Keir > >> Jan >> >>> Apart from that: >>> Acked-by: Keir Fraser >>> >>>> Signed-off-by: Jan Beulich >>>> >>>> --- a/xen/arch/x86/traps.c >>>> +++ b/xen/arch/x86/traps.c >>>> @@ -1544,11 +1544,11 @@ static int read_descriptor(unsigned int >>>> asm volatile ( >>>> "larl %2,%0 ; setz %1" >>>> : "=r" (a), "=qm" (valid) : "rm" (sel)); >>>> - BUG_ON(valid&& ((a& 0x00f0ff00) != *ar)); >>>> + WARN_ON(valid&& ((a& 0x00f0ff00) != *ar)); >>>> asm volatile ( >>>> "lsll %2,%0 ; setz %1" >>>> : "=r" (l), "=qm" (valid) : "rm" (sel)); >>>> - BUG_ON(valid&& (l != *limit)); >>>> + WARN_ON(valid&& (l != *limit)); >>>> } >>>> #endif >>>> } >>>> >>>> >>>> >>>> _______________________________________________ >>>> Xen-devel mailing list >>>> Xen-devel@lists.xensource.com >>>> http://lists.xensource.com/xen-devel >> >> > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >