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Wed, 22 Jun 2022 18:50:42 +0000 Received: from BYAPR12MB2759.namprd12.prod.outlook.com ([fe80::a0be:c49b:ef2c:e588]) by BYAPR12MB2759.namprd12.prod.outlook.com ([fe80::a0be:c49b:ef2c:e588%5]) with mapi id 15.20.5353.022; Wed, 22 Jun 2022 18:50:41 +0000 From: "Kalra, Ashish" To: Dave Hansen , "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" CC: "tglx@linutronix.de" , "mingo@redhat.com" , "jroedel@suse.de" , "Lendacky, Thomas" , "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" , "bp@alien8.de" , "Roth, Michael" , "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" Subject: Re: [PATCH Part2 v6 05/49] x86/sev: Add RMP entry lookup helpers Thread-Topic: [PATCH Part2 v6 05/49] x86/sev: Add RMP entry lookup helpers Thread-Index: AQHYhkJMEjVRVcpx502HVSPCQUlAqK1bejcAgAACPYCAAD2E8IAAAkWAgAAEHtCAAALbAIAAAJ6Z Date: Wed, 22 Jun 2022 18:50:41 +0000 Message-ID: References: <8f63961f00fd170ba0e561f499292175f3155d26.1655761627.git.ashish.kalra@amd.com> <25be3068-be13-a451-86d4-ff4cc12ddb23@intel.com> <681e4e45-eff1-600c-9b81-1fa9bdf24232@intel.com> <99d72d58-a9bb-d75c-93af-79d497dfe176@intel.com> In-Reply-To: <99d72d58-a9bb-d75c-93af-79d497dfe176@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_4342314e-0df4-4b58-84bf-38bed6170a0f_Enabled=True;MSIP_Label_4342314e-0df4-4b58-84bf-38bed6170a0f_SiteId=3dd8961f-e488-4e60-8e11-a82d994e183d;MSIP_Label_4342314e-0df4-4b58-84bf-38bed6170a0f_SetDate=2022-06-22T18:44:58.9604725Z;MSIP_Label_4342314e-0df4-4b58-84bf-38bed6170a0f_ContentBits=0;MSIP_Label_4342314e-0df4-4b58-84bf-38bed6170a0f_Method=Standard x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 11988241-6c5b-4851-dfac-08da54801b55 x-ms-traffictypediagnostic: CY4PR12MB1557:EE_ x-microsoft-antispam-prvs: x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; 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dmarc=pass (policy=quarantine) header.from=amd.com; arc=pass ("microsoft.com:s=arcselector9901:i=1"); spf=pass (imf05.hostedemail.com: domain of Ashish.Kalra@amd.com designates 40.107.236.40 as permitted sender) smtp.mailfrom=Ashish.Kalra@amd.com X-Rspamd-Server: rspam03 X-Stat-Signature: pg5gogg9hquxyhanstgprziximu9sajk X-HE-Tag: 1655923846-55417 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --_000_BYAPR12MB275973E9DAE91552FA0DE9E98EB29BYAPR12MB2759namp_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable [AMD Official Use Only - General] [AMD Official Use Only - General] ________________________________ From: Dave Hansen Sent: Wednesday, June 22, 2022 1:43 PM To: Kalra, Ashish ; x86@kernel.org ; = linux-kernel@vger.kernel.org ; kvm@vger.kerne= l.org ; linux-coco@lists.linux.dev ; linux-mm@kvack.org ; linux-crypto@vger.kerne= l.org Cc: tglx@linutronix.de ; mingo@redhat.com ; jroedel@suse.de ; Lendacky, Thomas ; hpa@zytor.com ; ardb@kernel.org = ; pbonzini@redhat.com ; seanjc@google.com ; vkuznets@redhat.com ; jmattson@google.com ; luto@kernel.org ; dave.hansen@linux.in= tel.com ; slp@redhat.com ; pgo= nda@google.com ; peterz@infradead.org ; srinivas.pandruvada@linux.intel.com ; rientjes@google.com ; dovmurik@linux.ibm.com ; tobin@ibm.com ; bp@alien8.de ; Roth, Michael ; vbabka@suse.cz ; kirill@shutemov.name ; ak@linux.intel.com ; tony.luck@intel.com ; marcorr@google.co= m ; sathyanarayanan.kuppuswamy@linux.intel.com ; alpergun@google.com ; dgilbert@redhat.com ; jarkko@kernel.org Subject: Re: [PATCH Part2 v6 05/49] x86/sev: Add RMP entry lookup helpers On 6/22/22 11:34, Kalra, Ashish wrote: >> So, if the RMP entry format changes in future processors, how do we >> make sure that the kernel does not try to use *this* code on those >> processors? > Functions snp_lookup_rmpentry() and dump_rmpentry() which rely on > this structure definition will need to handle it accordingly. >In other words, old kernels will break on new >hardware? >I think that needs to be fixed. It should be as >simple as a >model/family check, though. If someone (for >example) attempts to use >SNP (and thus snp_lookup_rmpentry() and >dump_rmpentry()) code on a newer >CPU, the kernel should refuse. More specifically I am thinking of adding RMP entry field accessors so that= they can do this cpu model/family check and return the correct field as pe= r processor architecture. Thanks, Ashish --_000_BYAPR12MB275973E9DAE91552FA0DE9E98EB29BYAPR12MB2759namp_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

[AMD Official Use Only - General]


[AMD Official Use Only - General]



From: Dave Hansen <dave.hansen@intel.com>
Sent: Wednesday, June 22, 2022 1:43 PM
To: Kalra, Ashish <Ashish.Kalra@amd.com>; x86@kernel.org <x= 86@kernel.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kerne= l.org>; kvm@vger.kernel.org <kvm@vger.kernel.org>; linux-coco@list= s.linux.dev <linux-coco@lists.linux.dev>; linux-mm@kvack.org <linux-mm@kvack.org>; linux-crypto@vger.kernel.org <linux-crypto@= vger.kernel.org>
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Subject: Re: [PATCH Part2 v6 05/49] x86/sev: Add RMP entry lookup he= lpers
 
On 6/22/22 11:34, Kalra, Ashish wrote:
>> So, if the RMP entry format changes in future processors, how do w= e
>> make sure that the kernel does not try to use *this* code on those=
>> processors?
> Functions snp_lookup_rmpentry() and dump_rmpentry() which rely on
> this structure definition will need to handle it accordingly.

>In other words, old kernels will break on new >hardware?

>I think that needs to be fixed.  It should be as >simple as a >model/family check, though.  If someone (for >example) attempts= to use
>SNP (and thus snp_lookup_rmpentry() and >dump_rmpentry()) code on a = newer
>CPU, the kernel should refuse.

More specifically I am thinking of add= ing RMP entry field accessors so that they can do this cpu model/family che= ck and return the correct field as per processor architecture.

Thanks,
Ashish
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