Received-SPF: pass (google.com: domain of linux-kernel+bounces-130689-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <0d63a41b-10b8-4c28-9919-877cc394a96c@intel.com>
Date: Thu, 4 Apr 2024 11:33:30 +1300
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCHv9 09/17] x86/mm: Adding callbacks to prepare encrypted
 memory for kexec
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Thomas Gleixner
	<tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov
	<bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>
CC: "Rafael J. Wysocki" <rafael@kernel.org>, Peter Zijlstra
	<peterz@infradead.org>, Adrian Hunter <adrian.hunter@intel.com>, "Kuppuswamy
 Sathyanarayanan" <sathyanarayanan.kuppuswamy@linux.intel.com>, Elena
 Reshetova <elena.reshetova@intel.com>, Jun Nakajima <jun.nakajima@intel.com>,
	"Rick Edgecombe" <rick.p.edgecombe@intel.com>, Tom Lendacky
	<thomas.lendacky@amd.com>, "Kalra, Ashish" <ashish.kalra@amd.com>, "Sean
 Christopherson" <seanjc@google.com>, Baoquan He <bhe@redhat.com>,
	<kexec@lists.infradead.org>, <linux-coco@lists.linux.dev>,
	<linux-kernel@vger.kernel.org>, Nikolay Borisov <nik.borisov@suse.com>
References: <20240325103911.2651793-1-kirill.shutemov@linux.intel.com>
 <20240325103911.2651793-10-kirill.shutemov@linux.intel.com>
Content-Language: en-US
From: "Huang, Kai" <kai.huang@intel.com>
In-Reply-To: <20240325103911.2651793-10-kirill.shutemov@linux.intel.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?TUxxZEtUWGFoM1d2RWdHaXkzMFJiWWVDSjFlVUJqdE9wbkpjTGxsVWVZTUJF?=
 =?utf-8?B?SVErU3FmUFozQ1RrRlBGdHF4SCtycnI3dXJZVWdEN1lEeER2WUNORFBIb1pq?=
 =?utf-8?B?eEl1ZVJFWU85VVJLS0diYU1TS2tVQ1hUL1VDdHRCM0pCTVJXLzcrSmROZ0ZS?=
 =?utf-8?B?cDBDTVNOejgrWGdTbzNrRmNTek5VczJzR2VuaVdEcE51VDR4OVkwMCtheG5D?=
 =?utf-8?B?ZTlNZW9JVTY4d0pXUElIT1E1Z1hqS2dvOXhESHN6ek9aOWxBb0hPQldUenJD?=
 =?utf-8?B?dWdLMmZJV0l4OEZpekcwYmZkOHovR0w4U1pPTHZSOUdER1BOOC80WlBKbnkz?=
 =?utf-8?B?Z0E3cTBPYUlXZ3RhYlpxU2FLYVIxQkhCZ3lzZ1dKVTJ0OGwzQUMyckRhVkFM?=
 =?utf-8?B?N1d5VG5pd1lLcWFSZHZYN1hxWTVSZk52aWpWUEtTK3RiUVhPaHQyLzFqUTFo?=
 =?utf-8?B?U2JPMEdjK1I3ejRoVkFWUEoyYWNkMmNBdW1HWVNOUWpKd3BYbk9NSFJjcTNi?=
 =?utf-8?B?aGR1RnBYSzNoSndHSXlJTEliRTRJRDl3UVRCdFg0OHpyQWxZdS9XZjdNVVJl?=
 =?utf-8?B?cEhWVXdETVEyWXJYOWhobE5DeDNlRXB4VytjWWd1QlZ4MHAwcWo0YXhGSEFy?=
 =?utf-8?B?VkNDSVh1eXltSzhYZExJS050ZXkvMzE5OHRQd1B1QkRGcW4xazdDT3NRZmk5?=
 =?utf-8?B?d1REQld2ZmFKMEIzRG50dTlMbndZMUhyRXFmMVRKeVJTdTM2YXFQbVRtNldE?=
 =?utf-8?B?TzgwS0E3RUVFaEUxa2tpVERrQ3VuSndsNEw2SlVPcml1YUQxV1ZmRFQ2L3dM?=
 =?utf-8?B?TDdMY3FYTkdobmE3akVjZnYzQldlYnk1Mm9QUzRKeGtaSnJ4NmZPSVJSeEVF?=
 =?utf-8?B?SjcxY1FZd1A0bEZPOEdvN3AwVzNQYnd2dkFZS3FHYmFZNitLSnF1cDc1ZklF?=
 =?utf-8?B?V2dFRVB0aXdlUzRRVkNVWTZzNFJzUzhFeS9MK0JQcG45NU9na2ZJZHBmVWI2?=
 =?utf-8?B?ZWRnTC9SdGo0cmE1WkVYaUQwNHFtVDB5MlJTeXJ6eG5UNmpSUTJkSEZkVllh?=
 =?utf-8?B?aWlVdGlkUlJiUjNkcG1uRUwxanFrZVFSZGJwWkdTQ2pZNVlYYm5hcWR1YW1Z?=
 =?utf-8?B?bWtTSjhob3JYbjVHQVkxaUphUHdTNzBGMThRYytHWDZSOW1NYnBtbHlmd01I?=
 =?utf-8?B?dUdyVDFvS1p2ZWtENTVQRnlaenZKb09HcW5QZUx0d0ZZZXp5WnRoaWpkZGdW?=
 =?utf-8?B?K3o1dC9rdExXWGkvYzR1S0FXZWRVTitvSG0ya3NtMHhEWDNpemtLcEIzY1gz?=
 =?utf-8?B?ckZZSXZ3WW1GRDJQRHBSa01WV3NNTkM3U3E4WGV6Q2IvZGQvZU9LY1ZiWk9P?=
 =?utf-8?B?bFNlUHEzNm9icS9KcE40eGNzNHZ3OVU0RHpSd01DN1hQdHFOV3RJV1JFYUVE?=
 =?utf-8?B?SFgvUnYxTTVoSWRlRFJta3JIM2NNNVg1QjhRZHZ0UkZSa1Q2UkRLbXBIRGE5?=
 =?utf-8?B?TTdiV1dOamszMDYwbERKeTZQQjRsVVBtSHkvdXhOcGR6WE82MVU0NDNKaDVR?=
 =?utf-8?B?VFZjcGUzcjE1dFpNSWdmOUtSN2txU3NDa3JBWlBua2JXOTlOQ3hvZGhVVXJw?=
 =?utf-8?B?Nkc0MHhtR1F1eEZQSG80UFR1eGVHQkR5WHhmK0YzMWJ0SU1Pa21iNVBNZ2V3?=
 =?utf-8?B?L3VpZFdMWDBUbWxiME9QZ0JIOFZhL2pCTjU5azIzUjZmWHd4K0hIeWhibjA2?=
 =?utf-8?B?S3hwWUozeERVOE41NTFEU0FYUXFqb05pbnlScHJrODZmdThvUmpESi8vMWIr?=
 =?utf-8?B?U0hRdlpWaVJhLzdWN09QVlZnZ09wSmRRK0NReVk4VmxCd0hibzFVNmRja3ZR?=
 =?utf-8?B?ZE9UdTFJaGxCdFVkSGhidzJUV0wzdnlzU2JQUEpEMzF6bnRUUVlmcGtxOG1R?=
 =?utf-8?B?UGlFcmxRNFVlaEhtdDZUK0ppTnlsRHhSNUhVdlVlRXpBai9KSGNFdEsrSmdC?=
 =?utf-8?B?WDNFOXNkTmptMUVvWks0OGIrWWVibTVXSVNOKzlnMmpYTElERlRxOWNGVi9v?=
 =?utf-8?B?T281eTFrUnpnK21oVEVlZEpRR0E1SmNta0RsVEx3K21keWZqRkFIWVVWMTVm?=
 =?utf-8?Q?ArHaRUnvvqHmiS5Np0DVf6iEl?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 53002539-b671-4fb5-87e9-08dc542e1dd5
X-MS-Exchange-CrossTenant-AuthSource: BL1PR11MB5978.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Apr 2024 22:33:42.7968
 (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: nQr7q60Tb9vDTPkOE8CjdXiT4Bb8odnVAHbmovCzxnzk/TZEU8Uo0pNGLe3GP53kadU3dqG2WzxvxWxSZ8N9iA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR11MB7322
X-OriginatorOrg: intel.com


On 25/03/2024 11:39 pm, Kirill A. Shutemov wrote:
> AMD SEV and Intel TDX guests allocate shared buffers for performing I/O.
> This is done by allocating pages normally from the buddy allocator and
> then converting them to shared using set_memory_decrypted().
> 
> On kexec, the second kernel is unaware of which memory has been
> converted in this manner. It only sees E820_TYPE_RAM. Accessing shared
> memory as private is fatal.
> 
> Therefore, the memory state must be reset to its original state before
> starting the new kernel with kexec.
> 
> The process of converting shared memory back to private occurs in two
> steps:
> 
> - enc_kexec_stop_conversion() stops new conversions.
> 
> - enc_kexec_unshare_mem() unshares all existing shared memory, reverting
>    it back to private.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>x
> ---

Reviewed-by: Kai Huang <kai.huang@intel.com>