From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2061.outbound.protection.outlook.com [40.107.94.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 41559A31; Sun, 3 Nov 2024 14:23:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.94.61 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730643795; cv=fail; b=AG1jWhF7qHbiCRREyCXR9SzksfwfR2h9EEaEneIEzsMAeJLG+NUjsRnGidu75xauA4lEozgf0Qpb+1KLjtFdfmxSY3evjXrxlh9sebbsyHz5REhpE2kbWDhfyifXNOBzZD0/Z/xFBcwAb+2qAR1QHz3ClUwtmj4EsQEoXHTs0ZM= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730643795; c=relaxed/simple; bh=R//BYe6uzIs1YqLHgTZiKmQfstjs7Q40pD1UMX0NYkg=; h=Message-ID:Date:From:Subject:To:Cc:References:In-Reply-To: Content-Type:MIME-Version; b=ql4FFUFgpaxTcxnI0za/1naJKieNZtaRl3J0R0NbHM/qvIaK3pZQ8YXy4gMNckpTP7rZqYDOpThhCvKQfMi8sZDTaNubfXHW3GvU7n7xsywAN1hdQIQi1Bj15LUgX6ELhSohjFeNoNtN66JiU2O8qhvt+YwCt8voH14c2fWnt84= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=zrD0xas5; arc=fail smtp.client-ip=40.107.94.61 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="zrD0xas5" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=sjzEXD3q6zXocwEPND1FPLoB3bJxLK8cHIyoZYY0o2f52zKSX7+CxfrnWWsUQXwdy9+uFmJQNoXl4Wi617qX1O490sbjj3pkR4OAb+Psj2oNijOMOUPIMNe0QfoZVPmZRcUqQ0FNMkjKH6GIdf/CRQMBW5Vw/SnErDEQFxDkLmcsWHgHJ+GMtXfahg3MgVQwtNWsEeyP4bJWkpDFZ/lPvRqiGYFkzF0T/+b56o1GK0DSXHi9zgRUXqzaVib7X0iMXLZ9U1KgNpTjUKBoFA3i4hQ4u3EeqR5l3wdOydXo/Q0kIkFY6G1nfLYX46GjKRmpjMQKTzuSv0nzho1bFlycPg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=/GgxN44ehDD5WQrwnzjj1T5+nSt2WCTGUiDoxJMGKdU=; b=eCI206+zDETy7XYZlo00K+iXubk9VM8lbNxs7Re8q+iaacJDPr+dm4l5JhE3QO4FK365evfMxplUGGsxAEHFGg5xhifDzpecc6mhjcRgwG0TrLIqynF+BwHg2zn8pkx+oyfsZE61EFDJDrWLG/U5PwFejg+ONfbLa1v7SXd45VT3sNpwjPXmL1/kkD2rjWp8Wn164g7rltQJyxdeO2ZQx0J7C6JueW4sS4n/nlP4CvJu+mVJMwUxZxiAnAmF3JQTg1J0tddPaDCyPcAxolzemiVoWOsR8PMQzwPLYkMPb9egBWc1foXuuYPO6KkmYKOFqX1Wa4329eWyFAfDrpCOWw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=/GgxN44ehDD5WQrwnzjj1T5+nSt2WCTGUiDoxJMGKdU=; b=zrD0xas5uc4omg6lLMfjbGcxEizJQkgM2VIlIySIS1cxlXyfzMaDMSNxAFG0nBJPgDbA40TssMPjCq4T40qCxDy/r8fe8/sLX51tM+ct41eTwWcuLcS9jvbNn4R+mYBnwe6e/rK0q8C12ZedfdRdezI5Pw8+r/W+aOeNb3bszVo= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DS7PR12MB6214.namprd12.prod.outlook.com (2603:10b6:8:96::13) by SJ2PR12MB9008.namprd12.prod.outlook.com (2603:10b6:a03:543::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8114.29; Sun, 3 Nov 2024 14:23:09 +0000 Received: from DS7PR12MB6214.namprd12.prod.outlook.com ([fe80::17e6:16c7:6bc1:26fb]) by DS7PR12MB6214.namprd12.prod.outlook.com ([fe80::17e6:16c7:6bc1:26fb%7]) with mapi id 15.20.8114.028; Sun, 3 Nov 2024 14:23:08 +0000 Message-ID: <74089281-3208-435d-93b3-22f1d794dfae@amd.com> Date: Sun, 3 Nov 2024 19:53:02 +0530 User-Agent: Mozilla Thunderbird From: Manali Shukla Subject: Re: [PATCH v3 2/4] KVM: SVM: Enable Bus lock threshold exit To: Sean Christopherson Cc: kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, pbonzini@redhat.com, shuah@kernel.org, nikunj@amd.com, thomas.lendacky@amd.com, vkuznets@redhat.com, bp@alien8.de, babu.moger@amd.com, Neeraj Upadhyay , Manali Shukla References: <20241004053341.5726-1-manali.shukla@amd.com> <20241004053341.5726-3-manali.shukla@amd.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: PNYP287CA0002.INDP287.PROD.OUTLOOK.COM (2603:1096:c01:23d::11) To DS7PR12MB6214.namprd12.prod.outlook.com (2603:10b6:8:96::13) Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB6214:EE_|SJ2PR12MB9008:EE_ X-MS-Office365-Filtering-Correlation-Id: 5f36fc6f-8d5c-40c5-5c76-08dcfc1309ce X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?N3V2WkRIMDJoQy9ZbUZoQnlMMGF4aUI5eFJSUW9Ta3pQZ1pSRWhPT0dHVzJQ?= =?utf-8?B?M1dYdFVjY0tCcUNmU2VDVkorZWlPc2dUWm5mUkpNV0ZCZEZXNjQrU0tnOFNC?= =?utf-8?B?aGNndXdpakxhUjlNZ2tHWHJ5RVU2TDJpeHVqL2x6NExEcElsZHNURzlWYTJM?= =?utf-8?B?VzdwSWtyQlp0UEFPQ21tNGlrVEZhd01UbkswRkkwbE52WVdyS0FweXozbTVh?= =?utf-8?B?UFVtbDlIN0tJWGVrbmhKOU1sK2hUL1hHalV2WGl4YVY0TGhVdGFtelFrYWxi?= =?utf-8?B?VGxJNzVwRFZHbytvWlFoMWlKVnZWYnVqL1lXbnd3T3lFYmgxT1JOckhZTWpF?= =?utf-8?B?VXN6aUoyemwyZUNjdzlJaWtreWxITkx4TnlEQUREelkvWkUrT1JMK0xDMERQ?= =?utf-8?B?Tk55TGg2RFRIOFppbG12Um1VaHFJbm94L1ZsRmFqd2sxMVNJVmo0TFEwUE96?= =?utf-8?B?VWxIdUl3ZmJlWUhodmRmMDBDVkE0WXBBRVBmRDdPbXBRK1V5TytGRzVqWXlm?= =?utf-8?B?b2wwdkdpN0dUUXlTWm1xVU1mTlFSaTJlNEt5TWxzTk84VlpqRGxmV09MZ2tP?= =?utf-8?B?K2o2eW9HSVQzNkMrclQvbWprK1V6aW1mMmtCU0FHMzRDV0FGVWJCMFpHcUJN?= =?utf-8?B?WDljSTRHVVNTQnBzcmE2V01Jd01vcE5zTlZaY1BWeU13YnV0Y3graWhPNDJi?= =?utf-8?B?RUZUOFgyNFZtT3dOcjV5OTROZHZxNStnTk8rWGdjRUtiZjd2ZzR4SkpYZldz?= =?utf-8?B?VjNXU0NYTGtEdklxdDNoN0ovRlhud21zSzFrVDB2ZnhKQVBRM3kvS09hQ2ZO?= =?utf-8?B?ZURJSWVYR3JTVTdIcHErTWw1WkRFN1B4dmc1MWR2aDlZRGgzM1VkK0tLK1Y5?= =?utf-8?B?V3IwNXdqc0x1QW1VL3FYQmFsc2xEZ0pxZkJySUFSRGVWZE1TTHM3NTYwSGE2?= =?utf-8?B?cjh3TnM4TUZXR1plZElZTWhybmlJMXdLQ3JwLzU4ckZIR0dQQmJQZysrc0pw?= =?utf-8?B?MWJoc2EvNWVPOXRCYnFaaUdkWnF0L1NGNFVQcHZlQVoyNWRVVjMza0sxZ2lF?= =?utf-8?B?eUxYb2o0Y3lpd3FWMlUvbVNxd0QrWWllNEdIbXV4ZkVpRjZ3OXhOeEFDNVU3?= =?utf-8?B?QUcrbEVHZUVjUFVVbUNuZWZPL1BOUXY0NFpmdGNpYmVQSlhqUWQyK1VEZnR2?= =?utf-8?B?d04vUjgyRnFOVU15NnBuYXhGdWpRTzF4dFN1MDJyQUZoM3pXbUFpeVEvWFhO?= =?utf-8?B?NVFuNW5PTHdqc1NtanAyY2wvSmNkbGNGYUM5OVB1OVNQNWRNRHBmd1o1N3kx?= =?utf-8?B?R1pMM2dHTGtOYWZ4bFNRTlhqclA0NlZ4S3RZVFJGL1grUGdBanJsNHQxWTZB?= =?utf-8?B?bUlORGYwV3VJZ1BTT3Nua0JiWUI4eUlnbXZZdFhjdEJady9PR3o1ekljNnRN?= =?utf-8?B?aXV4YUtXSll4aUdwUHRzdkI3TmFaL0lzOFdOalZabVMxdysyWkQ4MEE0dHlC?= =?utf-8?B?WWJ1bHVlNnhKOWpORlZiU0ErVklrNWxtanZMa3BBVFZvUFh5amUwbkE2Tmw2?= =?utf-8?B?ZmdmWFd5UEZ5Tkg3dEk0WmpXUzBrUnJGSmswUStCdDUzVmUxTWM2QUtLV1FB?= =?utf-8?B?T0RsY3NGeFNZTXpUSzJld0VKdWlTZ2pWdUdBeU4xL2lMbVJsT2RXa1NkRWxk?= =?utf-8?B?YTlZTEZHV1Z3eEY4b1VQL0ZROHA4Z2I4VlNMUk9LYzd3eHdxY0dkQ1NxQ1F1?= =?utf-8?Q?gaEM03x/yqiQ6wFPWY=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR12MB6214.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VzZRdDJITkVKdm1zNzVoTkpTNXFxbm83Wk5TcEVDRUFNUVBJejI5NXRDZnJy?= =?utf-8?B?bHBrVTROYWxxWlV5VkNUeWxRNi9yWVdRUFR2WS9UVTNYOWJ3cWlkZ3ZhY214?= =?utf-8?B?NkpuNW92UEtabEVkWTJIeEU1MUdHSTZzZWpPREw5VmRER05POGJrdUNRTXNO?= =?utf-8?B?eUdQN0xPdk1jS2toZ1J1eVhPdkRibmVndkppekhvbE9rcmxQKzlWRWEwVG0x?= =?utf-8?B?d3ZpWEI3bTlPVDNqczZXd0V2YU9RZksvcHFrcUpvYmpmZWVoWVBhQVQzNEZ4?= =?utf-8?B?M044SjEvVjIvbEx4cmxBQk9Tb2pGLzh5ZzFwdm8rVTF3QWYvOUtpbFh1VEFv?= =?utf-8?B?Rk8zNVk5Vkd2NkJqb0QrRnBHRjZBV3FNVWIrTkpxclVpeDFkaGJuZG5tOEVu?= =?utf-8?B?SDhDUUtxaUlROHEvVE9waDJMNjQ3N3lzL2NicGUwV3NrMjJUaEFJNHJNR1N0?= =?utf-8?B?VTVmYitaN21venVRcmxXcG1xWE5oVm1TOVVscytkZ1NYdVJENnZOYjFETWxK?= =?utf-8?B?ZkpFS256MnJ6NGVIckRhNGRIeGJmS3F5a2RneWVFUDhFUlZvdnBMdUlQdTZP?= =?utf-8?B?VXBxdlZaQmVsMTFPY25DKy8waHdnQ2NveHVXMTBFSGJ3dHNvS3RHSUVpWnJu?= =?utf-8?B?WlRGV3g3THBJNDRuUkQvZnpidDRMdVRLVlNzYmEyRWN6ZDJsN2RNMGpJMEV0?= =?utf-8?B?Z3d6Skkxb0hIM1p1b1dady9VU2hvZWt5b2cwelNnemM3ZGltUGRKNHhtY1Jp?= =?utf-8?B?QUZPRWEyd0Zaeng1d2RQb2paZ04yeE1ScmpEb0p0dUQzK3hRRUgvOVdyOWJl?= =?utf-8?B?NXdQRHAxdHlJb3o3dUtudnIyUDFoWGkrMzJZYS85SWZSaGVXMThvSndYUTFw?= =?utf-8?B?L25KMlhGZk1ET01VRWR6bmlMMW4rWGlNUVNTL0pMSHhSQk1hbHFkTzZuTTZH?= =?utf-8?B?bUszeHgyc042TFBScitpbnNxMjVub2dMMkdHMHN3Z2NYSzY1WGFZRHVvdU5X?= =?utf-8?B?UGhBVm1CZ2oyUnpKN0llMmtVZFB4a1BqUXJGaGtTbHhzUVA1Wms1L1lxUnFW?= =?utf-8?B?cjNjNWF3Z3dOd1dENnl4eUZBbCtWSnpRbERTaFdBNFg2dHRzMW1PckZXTEM2?= =?utf-8?B?ZzdRVWMxMGJGVTNuWWxLVDMxd2wzcElEMXlIdVg3aFByN3o4K1hpTjhwME9W?= =?utf-8?B?bXQ3bm1oc2FRNzUydDFGK1IybGFxRG01bURZakpJdkZkei83VmZWb3VMRGRQ?= =?utf-8?B?bmcvQkI5R212dG41SmRQdWtnN1VPVy9wRm5aM2lTbEd0MkdDdmlEVlJXSzZ5?= =?utf-8?B?c0Q5NlNNVzhKZ0VFaWpvczhDQmZWYTM2Z01rT1JUajV2MytLRlRQdGFsMXJl?= =?utf-8?B?RVdJaW1IakhsSC9VK04rcVFmcENFbU91ZEN2SVAyemtnZUhoSG9uRTBEMG1H?= =?utf-8?B?TXJBVkNTL0VBODl6OFZjTG9MaHVKSGY2MDZmeGh3OXp2VkluNEJ3ZkdWNDFQ?= =?utf-8?B?cWZtRmNYUkFRWndDNTFNMHVkNlRVcjNNT1JpdGYrMEEza1BwZnpBMUdQUFM2?= =?utf-8?B?a1c1VXNDUmoyWlZpVzVxSFVHMTF6OURhUXljdFBNTVh0dmVoQzUvNnNFREl0?= =?utf-8?B?eWVMRHJMYXRGZDl0T2JjcUphaC81TFVheUgrUjZReHgxeHkwb3FoYzZrNmxw?= =?utf-8?B?bzZMQU9wcWFyTmRSSitFQUVOOFpKRDhiMVlUdnEyMG1QbW8xc2FOTVBBRGtn?= =?utf-8?B?WDhLY1hyMnZ6Z29UdjZPN3kwblZjTVRVcjJSVk9KSGE0d0h4Y0lsY2o2MFZm?= =?utf-8?B?K0MvQXd1WW95RGxEeUowY2J3U1VJRG5qUE43VFVLaU5yYWE4ekRHcGwvQ1BR?= =?utf-8?B?MjZCTVdrek1zRUNpWTRZVjRCRXFkdW4vMjIvOVVrSUFxNms5UTVIWTJudSty?= =?utf-8?B?Rzh6MGpkZmFqam1icWxsWmhpbWhYQTcxMmpTZUNSenlBOVROclkxT0paQWNo?= =?utf-8?B?RGJlZG1HRHZBL2Jqb091NmxjOTVDSm55L2lXYnRNZVYwdVFFcnFuL3BuZDFC?= =?utf-8?B?bWJNYitWdjNuL01kazd0Z0VIRGhBMDZWcWxmL3BVT0ZGVkFsZWxCN3lsekVC?= =?utf-8?Q?cYLPTo7Z+RGKk6BvMJJMuSuWA?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5f36fc6f-8d5c-40c5-5c76-08dcfc1309ce X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB6214.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Nov 2024 14:23:08.2815 (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: C3JtgXv5JfW/3mOuEZTP+0lnazMmJlFrDakxDAGBeduZRexkYdt77urV6x/vo8Rzq1o750coXykHyT7Pm7u1Vg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB9008 On 10/15/2024 11:19 PM, Sean Christopherson wrote: > On Fri, Oct 04, 2024, Manali Shukla wrote: ... >> >> +static int bus_lock_exit(struct kvm_vcpu *vcpu) >> +{ >> + struct vcpu_svm *svm = to_svm(vcpu); >> + >> + vcpu->run->exit_reason = KVM_EXIT_X86_BUS_LOCK; >> + vcpu->run->flags |= KVM_RUN_X86_BUS_LOCK; >> + >> + /* >> + * Reload the counter with value greater than '0'. > > The value quite obviously must be exactly '1', not simply greater than '0. I also > think this is the wrong place to set the counter. Rather than set the counter at > the time of exit, KVM should implement a vcpu->arch.complete_userspace_io callback > and set the counter to '1' if and only if RIP (or LIP, but I have no objection to > keeping things simple) is unchanged. It's a bit of extra complexity, but it will > make it super obvious why KVM is setting the counter to '1'. And, if userspace > wants to stuff state and move past the instruction, e.g. by emulating the guilty > instruction, then KVM won't unnecessarily allow a bus lock in the guest. > > And then the comment can be: > > /* > * If userspace has NOT change RIP, then KVM's ABI is to let the guest > * execute the bus-locking instruction. Set the bus lock counter to '1' > * to effectively step past the bus lock. > */ > The bus lock threshold intercept feature is available for SEV-ES and SEV-SNP guests too. The rip where the bus lock exit occurred, is not available in bus_lock_exit handler for SEV-ES and SEV-SNP guests, so the above-mentioned solution won't work with SEV-ES and SEV-SNP guests. I would propose to add the above-mentioned solution only for normal and SEV guests and unconditionally reloading of bus_lock_counter to 1 in complete_userspace_io for SEV-ES and SEV-SNP guests. Any thoughts ? >> + * The bus lock exit on SVM happens with RIP pointing to the guilty >> + * instruction. So, reloading the value of bus_lock_counter to '0' >> + * results into generating continuous bus lock exits. >> + */ >> + svm->vmcb->control.bus_lock_counter = 1; >> + >> + return 0; >> +} >> + >> static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = { >> [SVM_EXIT_READ_CR0] = cr_interception, >> [SVM_EXIT_READ_CR3] = cr_interception, >> @@ -3353,6 +3374,7 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = { >> [SVM_EXIT_CR4_WRITE_TRAP] = cr_trap, >> [SVM_EXIT_CR8_WRITE_TRAP] = cr_trap, >> [SVM_EXIT_INVPCID] = invpcid_interception, >> + [SVM_EXIT_BUS_LOCK] = bus_lock_exit, >> [SVM_EXIT_NPF] = npf_interception, >> [SVM_EXIT_RSM] = rsm_interception, >> [SVM_EXIT_AVIC_INCOMPLETE_IPI] = avic_incomplete_ipi_interception, >> @@ -5227,6 +5249,11 @@ static __init void svm_set_cpu_caps(void) >> kvm_cpu_cap_set(X86_FEATURE_SVME_ADDR_CHK); >> } >> >> + if (cpu_feature_enabled(X86_FEATURE_BUS_LOCK_THRESHOLD)) { >> + pr_info("Bus Lock Threashold supported\n"); >> + kvm_caps.has_bus_lock_exit = true; >> + } >> + >> /* CPUID 0x80000008 */ >> if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || >> boot_cpu_has(X86_FEATURE_AMD_SSBD)) >> -- >> 2.34.1 >> -Manali