Received-SPF: pass (google.com: domain of linux-kernel+bounces-197253-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Message-ID: <75cb309b-b05c-42a0-a3ca-de08fa1cae59@amd.com>
Date: Fri, 31 May 2024 12:34:49 -0500
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCHv11 11/19] x86/tdx: Convert shared memory back to private
 on kexec
Content-Language: en-US
To: Borislav Petkov <bp@alien8.de>,
 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
 Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
 "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>,
 Sean Christopherson <seanjc@google.com>, "Huang, Kai" <kai.huang@intel.com>,
 Ard Biesheuvel <ardb@kernel.org>, Baoquan He <bhe@redhat.com>,
 "H. Peter Anvin" <hpa@zytor.com>, "K. Y. Srinivasan" <kys@microsoft.com>,
 Haiyang Zhang <haiyangz@microsoft.com>, kexec@lists.infradead.org,
 linux-hyperv@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
 Tao Liu <ltao@redhat.com>
References: <20240528095522.509667-1-kirill.shutemov@linux.intel.com>
 <20240528095522.509667-12-kirill.shutemov@linux.intel.com>
 <20240531151442.GMZlnpYkDCRlg1_YS0@fat_crate.local>
From: "Kalra, Ashish" <ashish.kalra@amd.com>
In-Reply-To: <20240531151442.GMZlnpYkDCRlg1_YS0@fat_crate.local>
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?VXZYUDdnVUZEY3BRM0VKUHFFNmVJUWJUT2RwMlVITWpvTnhFL3FNbG9JdjFr?=
 =?utf-8?B?OUQwYnhqaG03QnZjZjVOWlBKcndOVjE1RHlrQjBnTHFVS1VUaWZrZEtSQVB2?=
 =?utf-8?B?RlpNcjB1MzFxekRzUHp4d3FyWFRoc3VKU0hTV3JyTFZXVjRjMkJJNnpoWEVU?=
 =?utf-8?B?dWF3TisxdCtLT29mK0VxVk9rK1UrT0FPNXJzSDh5RXBESVJFcnZ0MHNPeHli?=
 =?utf-8?B?YW9rQW9LTzhCZnhpeTJ6Y0IyZC8yeTMwS1VkMzRUS01Kd2V5aGVaK2RYM1pO?=
 =?utf-8?B?aW5zQUxQSGdWWk5sVjg1VCtrdVRVcHp6cXErYkdSd0NFbUkvOTRkSzNJQW5u?=
 =?utf-8?B?M0tzdEp3Y09xMGUvTVBKeWg0ckNFTHJZb2xpVk1ERFpQU09nNHNTYU1PWHRT?=
 =?utf-8?B?bGVIdXg5amVuVTlHcFFtRmFubHJCZG5RY0ZnYkxRd3Z4elB3SG9Za2lZVU1E?=
 =?utf-8?B?S1p0dGdUQ0pSWlJjdEh1NlUySzhZMTF0YnVBNW5jd0pRejl6L3ZVN2cxT0Nk?=
 =?utf-8?B?L05hYUpkTWpoWVJzR2hLc3JUZHdDRFhLUUpyeXZLTHhzcGxuTkl4Z1hhQ0JU?=
 =?utf-8?B?YUp3R0pXRm1ZT05MVFpNRnFmR0phTHV4M2tpOGNOV2lETnFHUVV3QWRlWWtP?=
 =?utf-8?B?UFhLaU5QNW9QZm5kZEhnUWRqeUdtTElBNUtzYU9BMElmL1dSV3FnTExnZ0Ey?=
 =?utf-8?B?MWpxMEZUUE1sWWFrVm9tTGdGY2VOdkloaGUrYXJBMC85QnJOVVg4R2dzdVlF?=
 =?utf-8?B?bzZhLzlGQmttVVNKcUFxdG9aNmFybCsxNk8xalp5SWFPSU14WXRhMnh6dDFx?=
 =?utf-8?B?U2ZQUzdXdVYvSENCNWJsT21SSDdLN0ZuVjdEekhWY2pNeFh1WVJuNUh3K0c3?=
 =?utf-8?B?YjNjMGJuUVp5cFVQZFlPZHBPQTlHWWxiV3ZYVmg3SzVHRHgwR25FV1FXSU5C?=
 =?utf-8?B?VUtXcEZXeTBjYkNVUEJiWnZ2RkRYblhIeDFHWDQyUUN3WWh6bkZna3c1U09F?=
 =?utf-8?B?Q0RpL2IrTEE5dmtvb2Z4NVFLMFlpQ0hoSDMrQVlYbEIrc3hqZFJKYS92QTFm?=
 =?utf-8?B?NmN3L2w2YXc1ekVEUkdoNmlFUTZuVlplTTBsWURPaE5uZVQxNzRuSmlqc3Ez?=
 =?utf-8?B?T1ArS25TUjNjQjdJVE1sU2wzR09xcHUwTmhubTRVc0dsUllzUlRiVUR2eWZ5?=
 =?utf-8?B?TG1YYXBMcCttYnRWeCszd3lsRW1DbHF3dDJwWVhLSVV5QUZDakJqbXlOZVBE?=
 =?utf-8?B?RFNQRU5tMWpNRkFoelMyT3ZJdzM2YWNZa1FFOGVacEJUMlU0MGpJT25EMDNm?=
 =?utf-8?B?M21OTGZiQ3NxbzA4Ti9DZUkzL0Z3T0ZOTzFlYnl5RVFuOHJZc1dBOVFYa2Yr?=
 =?utf-8?B?RkwrSjZlTkVLbXh2Y1lxTHZpMEs0Ly9paEFmWTNQNmFrc0YvcEdUYSt6ZGI5?=
 =?utf-8?B?K3JWMjlsY2JBY0x1MnFRaEJxV2JIZGtxQVpJYzZnK3k1dkVwT2tROG9aU1Y2?=
 =?utf-8?B?RFZwdjBJam9UNExWcWNuQk5IMHdmdmJSQnpCdkNzWlRiUU1GNVp6d0lhbFJt?=
 =?utf-8?B?dmhGQS9taXo1eVVZeDl6M1plSWEzUklhb2Q1MFZ2RHNJdU13SGNOOEhSTmdt?=
 =?utf-8?B?UlVseGlYZk0rR0FTbU1rL3k1OUtnSXlRQk8wemR1ZVRXcHVlUUVjcmw4SnRj?=
 =?utf-8?B?RHBiUmkvYUJCUEd2T2RLRkJwaXNCYW1ubEc0S0tIU0VHcStCb1A5K2NRVmNY?=
 =?utf-8?B?d1kzVHMvS3E5cFRlVlkzdFhTTUJta2hYM1Z5VHI1RFNUVE1aVmdWMGVHRlBs?=
 =?utf-8?B?Q2d6TGxVRnp3NG14dFJiMEw0enJBZkdETmpKd21xSS9LVnJjaStnYmJ0dXBr?=
 =?utf-8?B?ZzI1bUROcHJ2c2RZWi9TUjR3K3hRN1JtZm1mVEVHeFU3bmJVcWJoUG16U1lM?=
 =?utf-8?B?S2hjUDcwaTVkVHZmMHR1TS85NkJUSmNMQzk3N3hNNkZPUmdvQ1A3ajV0Uk1T?=
 =?utf-8?B?elB2THhocWlndGJJc1RUcXNONUg0eEhIR3B3ZUdzSElpZzMwbjgxMjdRZnVq?=
 =?utf-8?B?MFo3MXI2c2lac0JSRHZJZ1E2SHhiOHVsdUt0WXl3UjZzMlR5R0FJTHVjcnZ3?=
 =?utf-8?Q?BBgkNZhiTwGfW9UBkd1RBYmOX?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: df64b88d-5847-41d3-8d6b-08dc8197faa5
X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2767.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 May 2024 17:34:52.6184
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: RluoCCIPvHPGUK1eLXUJ6QtR8F7LnSAZPticLq9SNyRw5eCyRC5Dq6EbdzORfMtAvUp/yxtg1R08csf+daBqzA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB6793

Hello Boris,

On 5/31/2024 10:14 AM, Borislav Petkov wrote:
>>   static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
>>   {
>> -	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
>> -		return __set_memory_enc_pgtable(addr, numpages, enc);
>> +	int ret = 0;
>>   
>> -	return 0;
>> +	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
>> +		if (!down_read_trylock(&mem_enc_lock))
>> +			return -EBUSY;
>> +
>> +		ret = __set_memory_enc_pgtable(addr, numpages, enc);
>> +
>> +		up_read(&mem_enc_lock);
>> +	}
> So CC_ATTR_MEM_ENCRYPT is set for SEV* guests too. You need to change
> that code here to take the lock only on TDX, where you want it, not on
> the others.

SNP guest kexec patches are based on top of this patch-series and SNP 
guests also need this exclusive mem_enc_lock protection, so 
CC_ATTR_MEM_ENCRYPT makes sense to be used here.

Thanks, Ashish