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Date:   Sat, 29 Dec 2018 23:26:43 +0800
From:   Yang Weijiang <weijiang.yang@intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     qemu-devel@nongnu.org, rkrcmar@redhat.com,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com,
        yu-cheng.yu@intel.com, yi.z.zhang@intel.com, hjl.tools@gmail.com,
        Zhang Yi <yi.z.zhang@linux.intel.com>
Subject: Re: [Qemu-devel][PATCH 2/4] Add CET SHSTK and IBT CPUID feature-word
 definitions.
Message-ID: <20181229152642.GA6590@localhost.localdomain>
References: <cover.1545806972.git.weijiang.yang@intel.com>
 <30d79c2d6fa0658cd2818c21da852fd4dfeeae1c.1545806972.git.weijiang.yang@intel.com>
 <97d6366b-df95-cf00-d652-3176547ae5ca@redhat.com>
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On Fri, Dec 28, 2018 at 03:25:10PM +0100, Paolo Bonzini wrote:
Thanks a lot Paolo for the comments!

I'll fix the issue in next version.

> On 26/12/18 09:25, Yang Weijiang wrote:
> > @@ -1233,6 +1252,14 @@ static const ExtSaveArea x86_ext_save_areas[] = {
> >            { .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_PKU,
> >              .offset = offsetof(X86XSaveArea, pkru_state),
> >              .size = sizeof(XSavePKRU) },
> > +    [XSTATE_CET_U_BIT] = {
> > +            .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
> > +            .offset = offsetof(X86XSaveArea, cet_u),
> 
> These offsets are incorrect, since supervisor states are only stored in
> the compacted format.  In fact, in patch 4, supervisor states should
> return 0 in CPUID(EAX=0Dh,ECX=n).EBX.
> 
> You can use offset == 0 to distinguish supervisor and user states, so
> that supervisor states are skipped in xsave_area_size and x86_cpu_reset.
> 
> Thanks,
> 
> Paolo
> 
> > +            .size = sizeof(XSaveCETU) },
> > +    [XSTATE_CET_S_BIT] = {
> > +            .feature = FEAT_7_0_ECX, .bits = CPUID_7_0_ECX_CET_SHSTK,
> > +            .offset = offsetof(X86XSaveArea, cet_s),
> > +            .size = sizeof(XSaveCETS) },
> >  };
> >  
> >  static uint32_t xsave_area_size(uint64_t mask)