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Mon, 11 Mar 2024 08:14:39 +0000 Date: Mon, 11 Mar 2024 15:44:46 +0800 From: Yan Zhao To: Sean Christopherson CC: Paolo Bonzini , Lai Jiangshan , "Paul E. McKenney" , "Josh Triplett" , , , , Kevin Tian , Yiwei Zhang Subject: Re: [PATCH 1/5] KVM: x86: Remove VMX support for virtualizing guest MTRR memtypes Message-ID: Reply-To: Yan Zhao References: <20240309010929.1403984-1-seanjc@google.com> <20240309010929.1403984-2-seanjc@google.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20240309010929.1403984-2-seanjc@google.com> X-ClientProxiedBy: SI1PR02CA0001.apcprd02.prod.outlook.com (2603:1096:4:1f7::15) To DS7PR11MB5966.namprd11.prod.outlook.com (2603:10b6:8:71::6) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR11MB5966:EE_|SJ2PR11MB7647:EE_ X-MS-Office365-Filtering-Correlation-Id: 3172c274-a666-4a34-16f5-08dc41a34c10 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: qwMRH/U3SDopuzRVGbLaqK3j/1xq7G22R1ATZgcIO7ZqCMm5IZwdTFw8XyJaHcu/ZOUbRKdtfSXhrRsVohAidDWQ2b6CC++arfWBbLo1s0QZGVFWqbqKz5KTEOXDyegtuUrZPclwp/MRAClCm2GlMjZsjTt7ha3VitneHf8Mka5Zc6j4Y0yLfxd3OI66utXu/+NyuHlbIgqiu4LICZ0oB/7mHqhMHo1+qpbejDTHpdRgFFAtxN4N81rF7wPJ0oBjmVPxA23k4Pz4fmIgCRhJAyrPq1cJ14uGkghJmROH1rlreENXDvx8CUpUUjtRNkZ8z6EvcwueDmHJBipGMmUS6J3Hhj0eDW5IV6YrzBbr3sDKqbbZN4DUSpt9ekUVE9zn8R4biR8ZrDmi60gIrFk1UlfpNsmoZEDavr+BU3jLRD7bXupHt39wOwzr/kzlaf+KCieUR/5RClPKq3JFM6ZIuZZgbYhgTgIx93D2GHrAf2FKPQqCgT4gakABSikT+FgvcV4a0Vk8ByOzuTzte1roiL2ZfBc3zsgst0SHR8cKoWD9DNsh7mWjbwmb4xTRL0tjNPEeaWgqQNESUU/CdzYR1c0RukiDGeqM8OpCjJx0GSe+GLo4mHhzvB1uQCsrbA8Gi3VA5EiSaM39u8f/AOnYlQ91NnZQfak+yxr4VEyPzEU= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS7PR11MB5966.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(1800799015)(376005);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?S/fluQj7rZQJcjbeBN7tMsE95KIq+4Gd3HbVStf2FEZ5gUZYV6/xs4mG7OmV?= =?us-ascii?Q?xK8ydkKW4MBUbLgxmn+uTOkjMx6dRJYvJUTt/2O9UOFeTyspIqLLrLk/Iz1g?= =?us-ascii?Q?eYPlqVjnSCH+U3+6j4B7EFlMnobMwzLnU7H0O5QyntjBlsvZW0DjaD4bOk/N?= =?us-ascii?Q?SO4vP7lVQZzw/J7JnKaXpKUunbsqfSUX8pe5vymm/Z5RolnU8eEeTXlZPWGu?= =?us-ascii?Q?D+ipzCmoALUkDH8JGf0wml63KmJHJsBop1eI07lZnAMXLntkGjYKB4aWNyWN?= =?us-ascii?Q?gNGIIuCW91owtsRxae43i/ZNCkm03vZHx++88S9Oje7S85QC+9JzIwOgsKIV?= =?us-ascii?Q?eun+eE0zO/VavzzXJenAr+oWZv6tF4ZAn8IaeW93sS7vUBx9CjFbf+Z65do0?= =?us-ascii?Q?CUachmS5qEX8QZL9Hyl/GmrcatwnB69byQkwGHA5E7t8QRpfe3uMfRvO/GSp?= =?us-ascii?Q?VWpxA3nbJKzrJzdW73h0kVce7Fu0RiOnzNbxbBonoHIXeYAJDfJZhCEhT/kw?= =?us-ascii?Q?ypp6Df4HI3LVOJ//drHPE6F2SlUojfVs9QLbw2dUFTrM/MGT3Eb3/aBiZGi6?= =?us-ascii?Q?cD7q5MSr5jdHUQV4oDtBzfB32COCWYzbbYwmADoQH6qUvDnx22VHyXG/G3Os?= =?us-ascii?Q?7zrO863HCLvyDXziweRtAhe2YO7U0BF2JRdLlBUAy5pAooUyZE2ssXedvhrU?= =?us-ascii?Q?8teyAzQ6ozorwd9E0DC9XmnqzGT/X8YpaU9jDK6hfk3eGL1pFvWB+ihNo6CF?= =?us-ascii?Q?wT+YV7qNTKzbBcn2v3j2LX02wH3r+NyyPji0jFiMwzo1cp8NiDNidU41cpiJ?= =?us-ascii?Q?6zkKsJUJlH+bmka0S9ub9z3foyWht43Ua4MTC2U0CjAK+woIxWZabTKlXx12?= =?us-ascii?Q?/Oge2Qk20i+DvsekUhvEgetsTZKfbd0rYYJGEA8y0d9cX6rMeiMbVv2Fw0AY?= =?us-ascii?Q?57pzvF7B/Gkj0n9yokrXxZXmnMsHAlyoTuHzL0pKYx9JsrvE1Blw+tpjiFPZ?= =?us-ascii?Q?kO/6EDagWy65IkBIbT6n/3wfzrEV1Ml8pcBim2AtCr0tKYmv9E1kH1vxR8O9?= =?us-ascii?Q?GNqTWvTDm6yjEqjNcnkY2XiXt6uIlxe9J30kyP+6nxnOUFSXnAuENLic/Byf?= =?us-ascii?Q?JCHbRCcm1v2YinDYadq0G9AXCNus/8HBy8BihPvCVeTjxh8PVIZCcbPDuqGl?= =?us-ascii?Q?/bHCkNXF+7urGNiteCf0ga5SGSRDbLH9wUXr6F45wHRCXki2P7tKWIKsh7Px?= =?us-ascii?Q?COanyo5eAJ4s94pvIiKHVf5GkUtHXKnF5luKH+OAjvy9Br8nGGOcoPw4e3DH?= =?us-ascii?Q?914foKbZOeYDI85Be90z5mYacCY9sBynzzRR15r8x48yNq2orL68p4LIUo3d?= =?us-ascii?Q?EqbgZBEcqUa45im7jkCeviZJ6532RlB//JyEmCpy00CoedqXUJCi5qtW8sIa?= =?us-ascii?Q?OxCSu/Tzu6XeXbOIEX2H9HqZS4HfMF+c7CZ1IxrVesFu8n5qbFcjfS/FkRCM?= =?us-ascii?Q?tYcTMAjhSIYq23te4ZJkpFbaEry0/Q+cUFM/jIaD/bAga6SyZYl687VKzTMu?= =?us-ascii?Q?vgLyCQnKkYpTJuLeJowhqlPMZJhaOCmsLYSY4zoR?= X-MS-Exchange-CrossTenant-Network-Message-Id: 3172c274-a666-4a34-16f5-08dc41a34c10 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Mar 2024 08:14:39.2708 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: PmL+3D7DP8cPns4LbcAsc11V6Czgp9L+GaqUezhVTzKGQmHX12U8Cf4P9TBAgGLTj16OkqeYdSNqfqtUdYP9Ug== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR11MB7647 X-OriginatorOrg: intel.com On Fri, Mar 08, 2024 at 05:09:25PM -0800, Sean Christopherson wrote: > index a67c28a56417..05490b9d8a43 100644 > --- a/arch/x86/kvm/mtrr.c > +++ b/arch/x86/kvm/mtrr.c > @@ -19,33 +19,21 @@ > #include > > #include "cpuid.h" "cpuid.h" is not required either. > -#include "mmu.h" > ... > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 7a74388f9ecf..66bf79decdad 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -7596,39 +7596,27 @@ static int vmx_vm_init(struct kvm *kvm) > > static u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > { > - /* We wanted to honor guest CD/MTRR/PAT, but doing so could result in > - * memory aliases with conflicting memory types and sometimes MCEs. > - * We have to be careful as to what are honored and when. > - * > - * For MMIO, guest CD/MTRR are ignored. The EPT memory type is set to > - * UC. The effective memory type is UC or WC depending on guest PAT. > - * This was historically the source of MCEs and we want to be > - * conservative. > - * > - * When there is no need to deal with noncoherent DMA (e.g., no VT-d > - * or VT-d has snoop control), guest CD/MTRR/PAT are all ignored. The > - * EPT memory type is set to WB. The effective memory type is forced > - * WB. > - * > - * Otherwise, we trust guest. Guest CD/MTRR/PAT are all honored. The > - * EPT memory type is used to emulate guest CD/MTRR. > + /* > + * Force UC for host MMIO regions, as allowing the guest to access MMIO > + * with cacheable accesses will result in Machine Checks. This does not always force UC. If guest PAT is WC, the effecitve one is WC. > */ > - > if (is_mmio) > return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT; >