From owner-freebsd-amd64@FreeBSD.ORG Wed Feb 12 19:43:54 2014 Return-Path: Delivered-To: freebsd-amd64@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 4E2EB7D2 for ; Wed, 12 Feb 2014 19:43:54 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 246331696 for ; Wed, 12 Feb 2014 19:43:54 +0000 (UTC) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 40B0AB976; Wed, 12 Feb 2014 14:43:52 -0500 (EST) From: John Baldwin To: freebsd-amd64@freebsd.org, Simon Matter Subject: Re: amd64/186061: FreeBSD 10 crashes as KVM guest on GNU/Linux on AMD family 10h CPUs Date: Wed, 12 Feb 2014 14:23:48 -0500 User-Agent: KMail/1.13.5 (FreeBSD/8.4-CBSD-20130906; KDE/4.5.5; amd64; ; ) References: <201402120740.s1C7e1Mn005809@freefall.freebsd.org> In-Reply-To: <201402120740.s1C7e1Mn005809@freefall.freebsd.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201402121423.48285.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Wed, 12 Feb 2014 14:43:52 -0500 (EST) X-BeenThere: freebsd-amd64@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Porting FreeBSD to the AMD64 platform List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Feb 2014 19:43:54 -0000 On Wednesday, February 12, 2014 2:40:01 am Simon Matter wrote: > The following reply was made to PR amd64/186061; it has been noted by GNATS. > > From: "Simon Matter" > To: bug-followup@FreeBSD.org > Cc: simon.matter@invoca.ch > Subject: Re: amd64/186061: FreeBSD 10 crashes as KVM guest on GNU/Linux on > AMD family 10h CPUs > Date: Wed, 12 Feb 2014 08:30:51 +0100 > > ------=_20140212083051_97180 > Content-Type: text/plain; charset="iso-8859-1" > Content-Transfer-Encoding: 8bit > > As noted by John Baldwin the change to mca.c is not needed. Attached patch > is what I'm using now with success. > > BTW: setting vm.pmap.pg_ps_enabled="0" in loader.conf does also mitigate > the issue but I guess it's not the optimal solution. Talking with Alan Cox, we do think the right fix is to change the test to enable the workaround. However, we'd rather not penalize VM's on other CPUs. What we would like to do instead is figure out a set of feature flags we can test that will assure us we are not on an AMD 10h CPU (e.g. features that are known to be Intel only, or are known to be on newer AMD CPUs). However, we haven't come up with that list yet. Assuming you do have 10h CPUs, it would be nice to see what cpuid flags are set for your processors. -- John Baldwin