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Message-ID: <46c33f3f-7911-25d9-4236-cbee661e9242@suse.com> Date: Thu, 1 Jun 2023 12:35:16 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v2 3/3] x86: Add support for AMD's Automatic IBRS Content-Language: en-US To: Alejandro Vallejo Cc: Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <20230530135854.1517-1-alejandro.vallejo@cloud.com> <20230530135854.1517-4-alejandro.vallejo@cloud.com> From: Jan Beulich In-Reply-To: <20230530135854.1517-4-alejandro.vallejo@cloud.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR3P281CA0049.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:4a::22) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|DB9PR04MB9819:EE_ X-MS-Office365-Filtering-Correlation-Id: 0ff3acf7-f00c-42e0-33f1-08db628be4c7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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I'd like to ask that you replace the acronym here. Then Reviewed-by: Jan Beulich > @@ -1357,7 +1367,9 @@ void __init init_speculation_mitigations(void) > */ > if ( opt_rsb_hvm ) > { > - setup_force_cpu_cap(X86_FEATURE_SC_RSB_HVM); > + /* Automatic IBRS wipes the RSB for us on VMEXIT */ > + if ( !(ibrs && cpu_has_auto_ibrs) ) > + setup_force_cpu_cap(X86_FEATURE_SC_RSB_HVM); I'll need to remember to adjust "x86: limit issuing of IBPB during context switch" once this change has gone in, as there's a use of the bit for other than alternatives patching. Jan