Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 28 Jan 2019 18:33:45 +0800
From:   Yang Weijiang <weijiang.yang@intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     rkrcmar@redhat.com, sean.j.christopherson@intel.com,
        jmattson@google.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 Z <yi.z.zhang@linux.intel.com>
Subject: Re: [PATCH v2 1/7] KVM:VMX: Define CET VMCS fields and bits
Message-ID: <20190128103345.GA29895@local-michael-cet-test.sh.intel.com>
References: <20190122205909.24165-1-weijiang.yang@intel.com>
 <20190122205909.24165-2-weijiang.yang@intel.com>
 <5a31eef0-2b6c-bdc2-c54b-5dc4cecf084d@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5a31eef0-2b6c-bdc2-c54b-5dc4cecf084d@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Jan 25, 2019 at 07:02:37PM +0100, Paolo Bonzini wrote:
> On 22/01/19 21:59, Yang Weijiang wrote:
> > On processors that support CET, VMX saves/restores
> > the states of IA32_S_CET, SSP and IA32_INTERRUPT_SSP_TABLE_ADDR MSR
> > to the VMCS area for Guest/Host unconditionally.
> > 
> > If VM_EXIT_LOAD_HOST_CET_STATE = 1, the host CET MSRs are
> > restored from VMCS host-state area at VM exit as follows:
> > 
> > - HOST_IA32_S_CET: Host supervisor mode IA32_S_CET MSR is loaded
> >                    from this field.
> > 
> > - HOST_SSP : Host SSP is loaded from this field.
> > 
> > - HOST_INTR_SSP_TABLE_ADDR : Host IA32_INTERRUPT_SSP_TABLE_ADDR
> >                              MSR is loaded from this field.
> > 
> > If VM_ENTRY_LOAD_GUEST_CET_STATE = 1, the guest CET MSRs are loaded
> > from VMCS guest-state area at VM entry as follows:
> > 
> > - GUEST_IA32_S_CET : Guest supervisor mode IA32_S_CET MSR is loaded
> >                      from this field.
> > 
> > - GUEST_SSP : Guest SSP is loaded from this field.
> > 
> > - GUEST_INTR_SSP_TABL_ADDR : Guest IA32_INTERRUPT_SSP_TABLE_ADDR
> >                              MSR is loaded from this field.
>
Thanks for review.

> There is no code in this series to pass these fields to and from
> userspace, and also to save/restore U_CET, INT_SSP_TAB, PL0_SSP and
> PL3_SSP across context switches.
> 
The kernel consumes these MSRs, please see kernel CET patch:
https://lkml.org/lkml/fancy/2018/11/20/225

> In addition, PL1_SSP and PL2_SSP should be supported even if the guest
> doesn't use them.  It makes sense to avoid intercepting them, but they
> should still be supported and switched (possibly only if nonzero).
> 
> Am I missing something, for example a dependency on host CET support?
> If not, how was this series tested?
> 
The guest CET feature is tested with kernel CET patches on internal
virtual platform.

> Paolo