Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 28 Nov 2022 23:51:09 +0000
From:   Sean Christopherson <seanjc@google.com>
To:     Isaku Yamahata <isaku.yamahata@gmail.com>
Cc:     "Huang, Kai" <kai.huang@intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Yamahata, Isaku" <isaku.yamahata@intel.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "Shahar, Sagi" <sagis@google.com>,
        "Aktas, Erdem" <erdemaktas@google.com>,
        "dmatlack@google.com" <dmatlack@google.com>
Subject: Re: [PATCH v10 034/108] KVM: x86/mmu: Add Suppress VE bit to
 shadow_mmio_{value, mask}
Message-ID: <Y4VJbfxwk2zQhkf5@google.com>
References: <cover.1667110240.git.isaku.yamahata@intel.com>
 <1c480a48c2697054b1cfe068fa073f4035648f9a.1667110240.git.isaku.yamahata@intel.com>
 <a0d5878b7280372fa2de49156d58f69fa07659cc.camel@intel.com>
 <20221117180220.GJ2350331@ls.amr.corp.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20221117180220.GJ2350331@ls.amr.corp.intel.com>
Precedence: bulk

On Thu, Nov 17, 2022, Isaku Yamahata wrote:
> On Wed, Nov 09, 2022 at 11:48:30AM +0000,
> "Huang, Kai" <kai.huang@intel.com> wrote:
> 
> > On Sat, 2022-10-29 at 23:22 -0700, isaku.yamahata@intel.com wrote:
> > > From: Isaku Yamahata <isaku.yamahata@intel.com>
> > > 
> > > Because TDX will need shadow_mmio_mask to be VMX_SUPPRESS_VE | RWX	
> > > shadow_mmio_value to be 0, make VMX EPT case use same value for TDX
> > > shadow_mmio_mask. ?
> > > 
> > 
> > TDX need to use different mmio_mask/value doesn't mean they need to be changed
> > for VMX guest.  I think the true purpose here is to still be able to use a
> > global shadow_mmio_mask for both TDX and VMX guests.  So please explicitly call
> > out.  
> 
> That's right. With this change, per-VM shadow_mmio_{value, mask} can be avoided.
> The common value can be used for both VMX and TDX.

No, the mask can be global, but the value needs to be per-VM.  VMX needs to
generate an EPT misconfig, but TDX needs to generate an EPT violation to get the
automagic #VE reflection.