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Date:   Thu, 2 Apr 2020 17:11:18 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Nadav Amit <namit@vmware.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        "Kenneth R. Crudup" <kenny@panix.com>,
        LKML <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jessica Yu <jeyu@kernel.org>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Xiaoyao Li <xiaoyao.li@intel.com>,
        Thomas Hellstrom <thellstrom@vmware.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX
 hypervisors
Message-ID: <20200402151118.GK20713@hirez.programming.kicks-ass.net>
References: <20200402123258.895628824@linutronix.de>
 <alpine.DEB.2.21.2004020641470.7052@xps-7390>
 <875zeinecr.fsf@nanos.tec.linutronix.de>
 <D07135B9-576F-4232-8A1B-BEC5D26F35B8@vmware.com>
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On Thu, Apr 02, 2020 at 02:47:33PM +0000, Nadav Amit wrote:
> > On Apr 2, 2020, at 7:37 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> > 
> > "Kenneth R. Crudup" <kenny@panix.com> writes:
> > 
> >> On Thu, 2 Apr 2020, Thomas Gleixner wrote:
> >> 
> >>> As Peter and myself don't have access to a SLD enabled machine, the
> >>> KVM/VMX part is untested. The module scan part works.
> >> 
> >> I just applied both of these patches to my (Linus' tip) tree, and unfortunately
> >> VMWare still hangs if split_lock_detect= is set to anything but "off".
> >> 
> >> Was there anything else I'd needed to do?
> > 
> > Hmm. Not really. Does dmesg show the warning when the VMWare module loads?
> > Something like:
> > 
> >  x86/split lock detection: disabled due to VMLAUNCH in module: ….
> 
> I ran an objdump on VMware workstation and indeed I do not see a
> VMLAUNCH/VMRESUME. I do see however VMXON which should also be good for
> detecting hypervisors. I will try to understand why VMLAUNCH is not there.

Let me send a version with VMXON detection added in as well.