Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <1c525bcd-fe77-276d-4697-ac2ec3e00182@amd.com>
Date:   Thu, 5 Jan 2023 15:46:13 -0600
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.2.1
Subject: Re: [PATCH Part2 v6 07/49] x86/sev: Invalid pages from direct map
 when adding it to RMP table
Content-Language: en-US
To:     Borislav Petkov <bp@alien8.de>
Cc:     Michael Roth <michael.roth@amd.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com,
        ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com,
        vkuznets@redhat.com, jmattson@google.com, luto@kernel.org,
        dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com,
        peterz@infradead.org, srinivas.pandruvada@linux.intel.com,
        rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com,
        vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com,
        tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com,
        dgilbert@redhat.com, jarkko@kernel.org
References: <cover.1655761627.git.ashish.kalra@amd.com>
 <243778c282cd55a554af9c11d2ecd3ff9ea6820f.1655761627.git.ashish.kalra@amd.com>
 <YuFvbm/Zck9Tr5pq@zn.tnic> <20221219150026.bltiyk72pmdc2ic3@amd.com>
 <Y6DEv4QuvIfwWlCW@zn.tnic> <ab96e918-c8b7-67d5-1dfd-320264858cec@amd.com>
 <Y63Jz01c7zLx03gQ@zn.tnic>
From:   "Kalra, Ashish" <ashish.kalra@amd.com>
In-Reply-To: <Y63Jz01c7zLx03gQ@zn.tnic>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?K1VGT05qSTU3eDk0QWdiM1RFNzdSaTljWjNqQXBpYVNRbzNXemxXeFZuWlRI?=
 =?utf-8?B?cUVYL2JpdnpOVTc5TUdsRHN5LzF3akNWQzZmVzlKbG12Ujc5VUU3WFllZlEy?=
 =?utf-8?B?YjVrcHFoaGVSRVpUb2kyQ2JuNExISnJEK2FkSEI3SXV6enlwWFFWZTNLQmVE?=
 =?utf-8?B?T1hvWDFYRVkya202clJqd3BuMGsyN1JsTXY3ZWQ4WmNERzZkdUYyNUZBV1o1?=
 =?utf-8?B?SERyYU00VUZ4MEtXUkd5WXgwZTZSR051MFBGaU0wRHJjOURpVFpmYzc2Q0lG?=
 =?utf-8?B?ZmV6QWZERXliQmg1alU4dHliNGsvTGVGT1Jxa29wTkhFdXgwYzBnb0UyQVhy?=
 =?utf-8?B?YlgvK24zb3UxU3Z2K0MyOHBxNlFYRjhLWnljdFJBcUVJRGQ2Yk1NRXVSR0Qr?=
 =?utf-8?B?M2NvUDdicVQwMW83WnFsMHhGVXIxSFZRZkh6eHUxN2xBek9BU1BEM2lKcXpB?=
 =?utf-8?B?aE1zTExJdU5zdHR3VWJ4WS9NS1hrVUhGTmVUWm9zbmRtb0FydExYYzQ5RDdW?=
 =?utf-8?B?dzFJVjhlUTY0amZ3SEVLcWpaU0JLK003bHhXc01vdUdOYkJGWDYxaCsrNk1I?=
 =?utf-8?B?bDNMZmRRaHpNWDFkbmUydFBnYTRCUE5FSDh5UnpINEM5U1BRd1F1Q2QwWFlZ?=
 =?utf-8?B?eWZOTlJxUzduZHJoaHgySUpnVFdkbGxaSEI2Y2FUS1hVSmNKTW45VWlUb0JS?=
 =?utf-8?B?c3ZHbkNaZzdRR3B3YmFtd2kwYnJkL3lKSHVwcnlLb3JobkFrUzZBZU5Ka2ZW?=
 =?utf-8?B?WTB5MGdKV0FpRmtUL3lkeG5sVWo4NXhCbEw4cThzTVpBaG9USmRvT0pSUEcr?=
 =?utf-8?B?aGFoL282c0h6WGU4RTBUbldoOFVHaWQ3OTVJNFJ3RkZFQlhoOFFvYmhwVXgx?=
 =?utf-8?B?ZkFzM2tuR3I2VnJkVVZxSFNXcjU1cldkcERjU3FsTjgzT3poR0xMRCt4eWEv?=
 =?utf-8?B?Rzl0eFJzTWljNUpDMnlCQ1lGb2c0TXJJbzZmQjVZTnZaYWYwbjlnZVdxQmp6?=
 =?utf-8?B?UkFLNFVtN3ZyNXBCWGFtNXNpYytsUFhJMWVrYkptaFRSUmNCUldUMWxhcklR?=
 =?utf-8?B?OW5iOVhNOTZISjB5QngxWncxOFBxSU02RTczZzBiQWUwaUpFZHVyNzhib3dP?=
 =?utf-8?B?eDROYXhCNEtEL2dQQ1Bld0d3dzhBY1krWnBjcWF2SnpJZWJzVVRQcDIzQ3VH?=
 =?utf-8?B?U1dod2hkSk5iWnJMVUNETzRnbEw0T1RsUldxd0dwa1p1cWsySWV4cjZNekdI?=
 =?utf-8?B?eFhobW5ZeisrejJ2bmNvRmptb2xlNEVCUEp1eGJicGVlS1V2QVRJT2g4ZFIz?=
 =?utf-8?B?Q0cyK0lNdGFiUFJwM250T1E0TUpoSXR4aGwwWmgrNmk1ZElMOFVaWkZ6Lytz?=
 =?utf-8?B?aGh0MFhqbGJzSlJNWFNEMXVHbWoyZUw4LytvWGJoMWR1cXpaNkUrcWgrcEhE?=
 =?utf-8?B?R2JmQnBYREtFZkJYd1duc1Z1dXlPWTRvZGxvKzdTVG9HbWVuRGNseG41MlMr?=
 =?utf-8?B?VXBsa3NjYnJhb0VteVpnODNlekwrS3d2cjRZdXRPUnZYeDNiR3pPUnBKMTJp?=
 =?utf-8?B?RUppTkxqc05xTHplUzBoclFPaktYcFYyRjlRTUJrb3RtRFp0RVBLTE5CSjY2?=
 =?utf-8?B?bWVTS1JXMTh1RjV4ZG1IaytnV3Q1L1RLcVI0SU1uL21zL041STV4ek55b2Iw?=
 =?utf-8?B?cjVrYWozU29Za3NETEMyZ003dkIyWVdmbWlhOWRoRHpMTGhxdGZTTk9aU2wx?=
 =?utf-8?B?ZWRGc1h3dXZhT0xHUVFiVHlKYTIwd3BBVHRQTW1Ec1A5bUhhOGZGdE40L0Ns?=
 =?utf-8?B?VVd0dDJlSWxiUUF4eW1HSFA4WHQweDBaMFZtdmRHa3NGS3ZuTjhXdm1ZdzYv?=
 =?utf-8?B?NlUrKy9Nd0syeFQzM3NuK0tBbWFVL0o5N01CeGN6bG5xL2owK0VsNG8rcUhI?=
 =?utf-8?B?dkQvbFdSOHlCbFMwa2xkeG1FTVZaTlBNSmZZak5oN2hLL0FkVW9JR25ER09j?=
 =?utf-8?B?dXVBYWtpaHJXQTQ4a1gxaXkxZXVuVU1aYXRHNGEvUnc4QXVHMnRVdktSQlFs?=
 =?utf-8?B?SmVSOXlFYzdIRHlxaFlyTE1zUkJWSHNGQUVVOHFPbW1kVVVSZ1ZzOC9qZUk0?=
 =?utf-8?Q?O+zkBW18HzDkozkA+yKrGxHkS?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: c985107f-2808-43aa-733e-08daef6647d1
X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2767.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jan 2023 21:46:19.9145
 (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: O0djPHJ6ZYbrnfARpiBeLP38ULaP4CrqNVXJ65rpMdJ9+qJuMcKgLe+nTuocZ3/3oIWe4A43quAKmrY4B4x6kw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8036
X-Spam-Status: No, score=-5.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS 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-crypto.vger.kernel.org>
X-Mailing-List: linux-crypto@vger.kernel.org

Hello Boris,

On 12/29/2022 11:09 AM, Borislav Petkov wrote:
> On Tue, Dec 27, 2022 at 03:49:39PM -0600, Kalra, Ashish wrote:
>> Milan onward,
> 
> And before ML there's no SNP, right?
> 

Yes, that's correct.

>> there is H/W support for coherency between mappings of the
>> same physical page with different encryption keys, so AFAIK, there should be
>> no need to flush during page state transitions, where we invoke these direct
>> map interface functions for re-mapping/invalidating pages.
> 
> Yah, that rings a bell.
> 
> In any case, the fact that flushing is not needed should be stated
> somewhere in text so that it is clear why.
> 
>> I don't know if there is any other reason to flush after modifying
>> the direct map ?
> 
> There's
> 
>          /*
>           * No need to flush, when we did not set any of the caching
>           * attributes:
>           */
>          cache = !!pgprot2cachemode(mask_set);
> 
> 
> Does the above HW cover this case too?

Actually, as both set_memory_p() and set_memory_np() are only 
setting/clearing the _PAGE_PRESENT flag and not changing any of the page 
caching attributes so this flush won't be required anyway.

Thanks,
Ashish

> 
> Thx.
>