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Date:   Thu, 15 Jun 2023 16:58:22 -0700
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 <21568052-eb0f-a8d6-5225-3b422e9470e9@intel.com>
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Subject: Re: [PATCH v3 10/21] KVM:x86: Add #CP support in guest exception classification
From:   Sean Christopherson <seanjc@google.com>
To:     Weijiang Yang <weijiang.yang@intel.com>
Cc:     Chao Gao <chao.gao@intel.com>, pbonzini@redhat.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        peterz@infradead.org, rppt@kernel.org, binbin.wu@linux.intel.com,
        rick.p.edgecombe@intel.com, john.allen@amd.com
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On Thu, Jun 08, 2023, Weijiang Yang wrote:
> 
> On 6/6/2023 5:08 PM, Chao Gao wrote:
> > On Thu, May 11, 2023 at 12:08:46AM -0400, Yang Weijiang wrote:
> > > Add handling for Control Protection (#CP) exceptions(vector 21).
> > > The new vector is introduced for Intel's Control-Flow Enforcement
> > > Technology (CET) relevant violation cases.
> > > 
> > > Although #CP belongs contributory exception class, but the actual
> > > effect is conditional on CET being exposed to guest. If CET is not
> > > available to guest, #CP falls back to non-contributory and doesn't
> > > have an error code.
> > This sounds weird. is this the hardware behavior? If yes, could you
> > point us to where this behavior is documented?
> 
> It's not SDM documented behavior.

The #CP behavior needs to be documented.  Please pester whoever you need to in
order to make that happen.