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;
Subject: Re: [PATCH v2] KVM: x86: use CPUID to locate host page table reserved
 bits
To:     "Huang, Kai" <kai.huang@intel.com>,
        "thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc:     "Christopherson, Sean J" <sean.j.christopherson@intel.com>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
References: <1575474037-7903-1-git-send-email-pbonzini@redhat.com>
 <8f7e3e87-15dc-2269-f5ee-c3155f91983c@amd.com>
 <2f3d8c9b146301183b891d8a441aa4a5c33b4c9d.camel@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <c1012d42-6e60-66c9-80ea-f6c26db37172@redhat.com>
Date:   Tue, 10 Dec 2019 10:18:51 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.1.1
MIME-Version: 1.0
In-Reply-To: <2f3d8c9b146301183b891d8a441aa4a5c33b4c9d.camel@intel.com>
Content-Language: en-US
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 10/12/19 04:53, Huang, Kai wrote:
> Right. Alghouth both MKTME and SME/SEV reduce physical bits, but they treat
> those reduced bits differently: MKTME treats those as keyID thus they can be
> set, but SME/SEV treats those as reserved bits so you cannot set any of them.
> 
> Maybe the naming of shadow_phys_bits is a little bit confusing here. The purpose
> of it was to determine first reserved bits, but not actual physical address bits
> . Therefore for MKTME it should include the keyID bits, but for SME/SEV it
> should not.

Not just the first reserved bit, but _some_ reserved bit such that all
consecutive bits up to bit 51 are reserved.

Paolo