From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kai Huang Subject: Re: [PATCH] x86/MCE: bypass uninitialized vcpu in vMCE injection Date: Thu, 08 May 2014 09:17:41 +0800 Message-ID: <536ADB35.7090807@linux.intel.com> References: <1399447758-11798-1-git-send-email-kai.huang@linux.intel.com> <536A3430.9060408@amazon.de> <536AD9FA.6050400@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <536AD9FA.6050400@linux.intel.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: "Egger, Christoph" , xen-devel@lists.xen.org Cc: yang.z.zhang@intel.com, jinsong.liu@alibaba-inc.com, kevin.tian@intel.com, dongxiao.xu@intel.com, JBeulich@suse.com List-Id: xen-devel@lists.xenproject.org On 05/08/2014 09:12 AM, Kai Huang wrote: > > On 05/07/2014 09:25 PM, Egger, Christoph wrote: >> On 07.05.14 09:29, Kai Huang wrote: >>> Dom0 may bring up less number of vCPUs than xen hypervisor actually >>> created for >>> it, and in this case, on Intel platform, vMCE injection to dom0 will >>> fail due to >>> injecting vMCE to uninitialized vcpu, and cause dom0 crash. >>> >>> Signed-off-by: Kai Huang >>> --- >>> xen/arch/x86/cpu/mcheck/vmce.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/xen/arch/x86/cpu/mcheck/vmce.c >>> b/xen/arch/x86/cpu/mcheck/vmce.c >>> index c83375e..72fe924 100644 >>> --- a/xen/arch/x86/cpu/mcheck/vmce.c >>> +++ b/xen/arch/x86/cpu/mcheck/vmce.c >>> @@ -356,6 +356,10 @@ int inject_vmce(struct domain *d, int vcpu) >>> if ( vcpu != VMCE_INJECT_BROADCAST && vcpu != v->vcpu_id ) >>> continue; >>> + /* In case of broadcasting, don't inject to uninitialized >>> VCPU */ >>> + if ( vcpu == VMCE_INJECT_BROADCAST && !v->is_initialised ) >>> + continue; >>> + >> What happens when you inject to exactly one uninitialized VCPU? >> I think what you want is this: >> >> /* Don't inject to uninitialized VCPU */ >> if ( !v->is_initialised ) >> continue; > Good suggestion indeed. In inject_vmce, the ret is initialized to > -ESRCH at beginning. In case of injecting to one particular vcpu, we > will simply bypass all loops of "for_each_vcpu" and don't do the > injection at all, while the ret remains -ESRCH. Looks it's the right > behaviour for AMD case. > > Thanks Egger for comments (and sorry that I forgot to CC you at > beginning:)). I'll follow your suggestion. Hi Egger, Forgot to say, the reason I didn't do this at beginning is this code will potentially impact vMCE injection behaviour on AMD platform. Considering I don't have AMD machine to test, so I can just do a theoretically analysis here. If you are OK with this, I'll follow your suggestion, Otherwise, I think Jan's suggestion is also good enough. Thanks, -Kai > > Thanks, > -Kai >>> if ( (has_hvm_container_domain(d) || >>> guest_has_trap_callback(d, v->vcpu_id, >>> TRAP_machine_check)) && >>> !test_and_set_bool(v->mce_pending) ) >>> > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel