From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH 2/2] microcode: Check whether the microcode is correct. Date: Wed, 25 Sep 2013 09:59:27 -0400 Message-ID: <20130925135927.GA3834@phenom.dumpdata.com> References: <1380113870-3641-1-git-send-email-konrad.wilk@oracle.com> <1380113870-3641-3-git-send-email-konrad.wilk@oracle.com> <5242E184.9080303@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VOpcv-0001Cr-3P for xen-devel@lists.xenproject.org; Wed, 25 Sep 2013 13:59:37 +0000 Content-Disposition: inline In-Reply-To: <5242E184.9080303@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper Cc: xen-devel@lists.xenproject.org, david.vrabel@citrix.com, jbeulich@suse.com List-Id: xen-devel@lists.xenproject.org On Wed, Sep 25, 2013 at 02:13:40PM +0100, Andrew Cooper wrote: > On 25/09/13 13:57, Konrad Rzeszutek Wilk wrote: > > We do the microcode code update in two steps - the presmp: > > 'microcode_presmp_init' and when CPUs are brought up: > > 'microcode_init'. The earlier performs the microcode update > > on the BSP - but unfortunately it does not check whether the > > update failed. Which means that we might try later to update > > a incorrect payload on the rest of CPUs. > > > > This patch handles this odd situation. > > > > Signed-off-by: Konrad Rzeszutek Wilk > > While not strictly relevant to this patch, I simply noticed when > reviewing it that ucode_blob is __initdata. Given the comment "The > cached microcode patch is applied when CPUs resume from a sleep state." > in the previous patch, what is the policy for reloading microcode after > deep sleep / cpu hotplug ? The underlaying architecture microcode (microcode_intel or microcode_amd) end up saving it in 'struct ucode_cpu_info' which is a per-cpu data structure (see ucode_cpu_info). They end up saving it when doing the pre-SMP (for CPU0) and SMP (for the rest) microcode loading. And naturally if one does a hypercall to update the microcode and it is newer, then the old per-cpu data is replaced. Would you like me to update the git commit description with this? > > > [v2: Redid it as we are not doing scan and at the same time] > > --- > > xen/arch/x86/microcode.c | 16 +++++++++++++++- > > 1 file changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/xen/arch/x86/microcode.c b/xen/arch/x86/microcode.c > > index 8136d44..0bc95e6 100644 > > --- a/xen/arch/x86/microcode.c > > +++ b/xen/arch/x86/microcode.c > > @@ -419,6 +419,7 @@ static int __init microcode_presmp_init(void) > > { > > void *data; > > size_t len; > > + int rc = 0; > > > > if ( ucode_blob.size ) > > { > > @@ -431,10 +432,23 @@ static int __init microcode_presmp_init(void) > > data = ucode_mod_map(&ucode_mod); > > } > > if ( data ) > > - microcode_update_cpu(data, len); > > + rc = microcode_update_cpu(data, len); > > + else > > + rc = -ENOMEM; > > > > if ( !ucode_blob.size ) > > ucode_mod_map(NULL); > > + > > + if ( rc ) > > + { > > + if ( ucode_blob.size ) > > + { > > + xfree(ucode_blob.data); > > + ucode_blob.size = 0; > > + ucode_blob.data = NULL; > > + } else > > + ucode_mod.mod_end = 0; > > + } > > } > > > > register_cpu_notifier(µcode_percpu_nfb); >