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;
Message-ID: <76a9a58a-06e6-2151-a3a6-a8b61a68ab15@intel.com>
Date:   Thu, 4 May 2023 09:30:47 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.10.0
Subject: Re: [PATCH v2 14/21] KVM:VMX: Add a synthetic MSR to allow userspace
 VMM to access GUEST_SSP
Content-Language: en-US
To:     "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "john.allen@amd.com" <john.allen@amd.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>
CC:     "sean.j.christopherson@intel.com" <sean.j.christopherson@intel.com>
References: <20230421134615.62539-1-weijiang.yang@intel.com>
 <20230421134615.62539-15-weijiang.yang@intel.com>
 <50366bbd8ff5adf164644dd406ea7337c174ec22.camel@intel.com>
From:   "Yang, Weijiang" <weijiang.yang@intel.com>
In-Reply-To: <50366bbd8ff5adf164644dd406ea7337c174ec22.camel@intel.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?K0N2NFc4MFlxdzdzL2cvM1AyUFFxRVZmNmdtdWNZNmdGRlFrR3llUldyL1Ix?=
 =?utf-8?B?M2d1ZGwvQXdDNUROekpsaFNMNE4xUk1kc25EWG9qNWVZRkp2MGovOE5kVmVN?=
 =?utf-8?B?RHI0amNRU09oTU1BWTBNMFlwOWtITnBXMXRvU2lDbDNFc1Qyb3k4NjFTKzdS?=
 =?utf-8?B?dzAycnhQK215S3hKOHFjS1FGVERFbDZqeGtGbytyMTJDMmFVZXBzbVllUDV3?=
 =?utf-8?B?ZG90K1ZrNzFCTDdrWXRCWTgrRDZ3T0xyWHN1UFlIaklQZjdKb2VXcXVsL2xU?=
 =?utf-8?B?M21NVE1uWTlSL0FJdTh5VEwrZG5lQ0NQbG1xSjEydW9TdHNTWWh3UGliUkVs?=
 =?utf-8?B?Z3p2dFZVZlJycDBWUm55WE1LSmhRUE1HdG1JNmVGcDRnalVXMzhqK1VsYStS?=
 =?utf-8?B?M2ZYTElDYlV0aER6Wk1WbHlhYVdueFY4TDlHcklBUVJDZEVxUE1jVE5LNVRp?=
 =?utf-8?B?WTkwZkJhbUxIYkhjZ3FtVU83a28zOU5VZHk4bytqQmpVSVpzZ0VVV3lwOW9t?=
 =?utf-8?B?ZmV1ek8rSWpxQUs3RkdLWmowYjlBSVRuNVZFRDlrZlE4RTVuWGtIS01uV2k2?=
 =?utf-8?B?UGdtTk5JSzlPbkRHY01ra2c5NjBteFRUQUFjdWZIZ1FqTjNuWkJzRjJDQjZq?=
 =?utf-8?B?SmZKMkx0K0pGbmVyc0ZqSEJVZzE4WWVrYWtja2VDWjRTdmFjSjZ6WEp2bFJ0?=
 =?utf-8?B?WEZQUVhwSnNtTGxMemdGU29uaElIWG95MWlEazVZV1VTTm5IVjEreEhHK3ov?=
 =?utf-8?B?WWE3NUpoelRoUVcydmFmWlJEelFYYWdwN2U3SHNmdTlqMklMUStqK291eTV2?=
 =?utf-8?B?a0lIdGhCZGpTMjE4Yks2bEQ3STVnN2lCWGppM2NwbVJiZ3V6KzA1TG9Nc0Vu?=
 =?utf-8?B?NkxKVWk4am5SMXVnL0hPUU9peHhUZWxqTU1YVjB5V0lTbjFOV3U5NEZwRmU3?=
 =?utf-8?B?R21VWTBycmVhZzNkU3NuRFV3TjMxZHdaZzF3VXlQWStDZTZEWDZrYUl5d0dp?=
 =?utf-8?B?bXZZSVdxNFlva0piMkEzQW5wSDc4eXhQVVhKTGJVMzBHRk5VVTZQczA0ZTQw?=
 =?utf-8?B?UURkZG1USHQwN2Znd2NrR1paeXZhQittLzJ0L1ByYmdvNmZuOUpGYmFsUUZw?=
 =?utf-8?B?amU2VFlWS3BiNjUxcko5dGVGV2xYM09WcmRETkxib1lLNFhIc0ZyQkt1bEgx?=
 =?utf-8?B?WDhwT3lHMTlZYU16KzVqUnJZbk5JTXZBSzRjSFlJMmlUNHVJM2JCSlFKTnht?=
 =?utf-8?B?YlpyTjRNbWFoa0JaTWVzS0s2R0E0VTBaaGlpTUEvUjJ1SDlJdmVPUnNVWFU3?=
 =?utf-8?B?UmVmU0ZnMGp5QU8yazZ1cWFrSEJUSEJwTXRzM3NPMnNkTTExL2xaSlMwclZ1?=
 =?utf-8?B?bU9xRHhSZDFxc2cwd0Z4N1lkVDZML05YTU1VMjhacXN1U2FlRzFHOW51VEtp?=
 =?utf-8?B?eHB5TUxyc3JaWmRXMVlaZWg5K3BKN1ZZQmxvT25VNGdsZ0VPenM5MyszV1Zp?=
 =?utf-8?B?WWMvcndWYUhhQS9Pa0ZQdGxFcDc0VS9CK1QzMmEzT2FRVGZFK0o0LzVvcys5?=
 =?utf-8?B?RVNjdkt4cE9TVThMNE1BQnQ1MlhGMWU1WkFlMmtuZDBqVC9FY0xaZVV1M1g4?=
 =?utf-8?B?WU9nQjVwaXRBSi9hZ3MrdWdjYVEra3lrWVBWdmh0TWFIeGFHTGlwTGF2dHQ4?=
 =?utf-8?B?MjRna0RYWWw0ODlQVXhERTFvbFVnZzlhaUZUYkVhVmVIZkt0Qm1lbXErM0dK?=
 =?utf-8?B?aG5hbW9mOGM1eTNOTzZWZHF3bnhRbUdqdmxuRVhMZUI3Nk54Yk1CL0dBUWs0?=
 =?utf-8?B?UmRGZUpDMGRvTGppVEozUWtlNEZrRnpER0tZMzIvc3dRRXQ3VFk2blU5bjdv?=
 =?utf-8?B?NjhLNmQ0TjlVTTFEZy9mSDZ1dkthREdVa3JUTGYxVnR6RitFUGNWRk5NbHRv?=
 =?utf-8?B?YUwvWUI2MGEyWkt3Y21uellnMHV2dDJLbDd0SzRDdmpaRW5keHBmMm1BU09l?=
 =?utf-8?B?QmxhV3pmcDlEYlkva1pod3ljK1FNemZJbEQzd2tadklNQlFFWnhFVGdSQ3Rn?=
 =?utf-8?B?eEhucjRYNlFzRlJNdzYvcGNOeHBJcXMyNFBUaHdJaDRkL0RYeWVXeWVyMjdQ?=
 =?utf-8?B?a1BWQXZWNFFiemZ0enhKb04zdUZmc2FubWFKNDBKaUlaUEZSZWVPeStqYUVh?=
 =?utf-8?B?eEE9PQ==?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 945498b8-e08b-4630-6989-08db4c3f374e
X-MS-Exchange-CrossTenant-AuthSource: PH0PR11MB4965.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 May 2023 01:31:00.1325
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 1AOKwvZf5UJTY3PVT/4xbdvi6pRFnon0jMTbk3gHHBG8dml5dw/uxNVIBhOcJUqj0aJ1OrkF6GrUrld/jXKiLw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR11MB7937
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-8.8 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,
        RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE,
        URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


On 5/4/2023 1:08 AM, Edgecombe, Rick P wrote:
> On Fri, 2023-04-21 at 09:46 -0400, Yang Weijiang wrote:
>> Introduce a host-only synthetic MSR, MSR_KVM_GUEST_SSP, so that the
>> VMM
>> can read/write the guest's SSP, e.g. to migrate CET state.  Use a
>> synthetic
>> MSR, e.g. as opposed to a VCPU_REG_, as GUEST_SSP is subject to the
>> same
>> consistency checks as the PL*_SSP MSRs, i.e. can share code.
> It seems this is exposed to the guest? I'm thinking maybe it should not
> be. IA32_PL0_SSP comes with some extra checks, so MSR_KVM_GUEST_SSP
> seems a bit powerful. I think the guest doesn't need it either.

Make sense. The MSR is just for live migration purpose, no need to 
expose it to guest,

will change it, thanks!