Received-SPF: pass (google.com: domain of linux-kernel+bounces-122369-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Thu, 28 Mar 2024 11:12:57 +0800
From: Chao Gao <chao.gao@intel.com>
To: <isaku.yamahata@intel.com>
CC: <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<isaku.yamahata@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>,
	<erdemaktas@google.com>, Sean Christopherson <seanjc@google.com>, Sagi Shahar
	<sagis@google.com>, Kai Huang <kai.huang@intel.com>, <chen.bo@intel.com>,
	<hang.yuan@intel.com>, <tina.zhang@intel.com>
Subject: Re: [PATCH v19 070/130] KVM: TDX: TDP MMU TDX support
Message-ID: <ZgTgOVNmyVVgfvFM@chao-email>
References: <cover.1708933498.git.isaku.yamahata@intel.com>
 <56cdb0da8bbf17dc293a2a6b4ff74f6e3e034bbd.1708933498.git.isaku.yamahata@intel.com>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <56cdb0da8bbf17dc293a2a6b4ff74f6e3e034bbd.1708933498.git.isaku.yamahata@intel.com>
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?6MyZCXjZZiGN+ccYeReW3+pEyN8AbnsTdlnYT8cUIrTgcE9Us02uzkskt/TN?=
 =?us-ascii?Q?NVVyFQvJMrwn5KNF1G4PoDu5FO5bitRDMl9qLQHx1vqXH+siPoHjBZ15cgWL?=
 =?us-ascii?Q?uZFidC2imP4mDpEF64LL7CPW0aKc2YeUBFIfxAlHcVHR00UIyJ3QCwJtUz0j?=
 =?us-ascii?Q?hnkHR+IjOkopeh4iF5mSKes2SUSQdEu12wsMsLWDZtpyLDQ9c0cPGrO+DaD/?=
 =?us-ascii?Q?N6u9UpPlo1z/82a/WPsk8+v8Mrod8hYXdP0nPIAqCFI7122LpfTdUcsj8HyO?=
 =?us-ascii?Q?dD0DrNKAL1oIz2FMJHR5/H2PZFsDUBn+dnWhfO/Sseemr5PQzYpC/NRsyOJ7?=
 =?us-ascii?Q?qZHRQUYvEi9ox6qYheQvS0Zsn8AlQ61jeJtNZ4+TVIgh8ic2n3mW7lb5Tsio?=
 =?us-ascii?Q?9rpLC/YoqilpxgRABwaLhTBId4G9IOoFMn5fQXjooenXVDcdk9sicbJkes87?=
 =?us-ascii?Q?TETpHjpZ17qmFygQLNKu7q9W5gy6p6HLIMNGPMCy4oQho+H5mo3fSDp6yvcZ?=
 =?us-ascii?Q?p+dU/YegrFKQ9hBJgC5i3ZOZMpUQASrrRb2ROaSFVHvjlmrAQWwkSL11g2O7?=
 =?us-ascii?Q?DJmdmvY9ft202av/sp3ftnaEONA+I+EfY1+/4xEaBz/Sxn4nzXy0Oez+lWtI?=
 =?us-ascii?Q?bFpVy29hcBSykl4p9BoPqIZrzdxWp0LT4MbWf3oDTmARpLevP690l9iuFTu9?=
 =?us-ascii?Q?j7f0NTR3IGyhOwuUAWPGaJVqJ0mWGQvVaecxVSrGZfIYUVNOR5nTVGAvY/uW?=
 =?us-ascii?Q?MN+FJw7gQUOQStG2TnU2KIyUbBBvNU+HotqN1cTbCmUBZ+kpgu/4RLKijeFc?=
 =?us-ascii?Q?eTx2diBVtiZBd9Mr6Lb6Opmv5mD7rUYp25LxJXtmqWKknA/gAnuFbYK0dhvm?=
 =?us-ascii?Q?00hfQZzRt+DJLNupEf8mBYzjmuG6OLFfyUrg+jHdVF1lfAmnhMUA3OxhhYwS?=
 =?us-ascii?Q?B0sU1LUUJ0iSXVM1rRM82Hbza0dX/geFkhIMaRs4PHWLUdmZyF2Xdeg0+pxw?=
 =?us-ascii?Q?FFTMUdQT6ohVox/+uvDEIRExpe4l4KoxSy694VE+CjZwXJG6VDauVipGC7cg?=
 =?us-ascii?Q?ssO7a3R+EiQfhWIF/erFkOR2JDbrkKF7G1fqUzP/sMIhgGuIynxZurOz128T?=
 =?us-ascii?Q?5oR/JPFA6mb4W/MCsEkDsBywbBZULVRVVFJgsag37r73m9MgVbR4fHOaQvPc?=
 =?us-ascii?Q?rJXSMg9KJ8NrzFCFVuEAKBbHWJbI0sAv9OAplUoYjTtsYCkCDTcBPrHSTIDF?=
 =?us-ascii?Q?a9HVs4pQsgB2CeJrwOeeoXqef3u1cUuPVl0RD7tXbtCjzz4/w0yqzC9kEomI?=
 =?us-ascii?Q?WpRVHICnpnqlVIvVtV3ELS7FM0AkTtEfYIwI1DoyH7r0eNS4hT/0WRwpXSar?=
 =?us-ascii?Q?y7KDu3k9vVdOuOfIgXUWIHw40fywqeyJa56drvRSzIwY7n+7WFbmrnAdxoHX?=
 =?us-ascii?Q?VcirMepHP37UqXPb2LVVTi0ToPsVqhOwb/+KPOePgUUSlDk0El9iD3Iaju2i?=
 =?us-ascii?Q?KMFQMmIdhtU++7dTCtTTXiEfI8zC+HO5wHSzAYAPVwBQy539JULOeM49TGT1?=
 =?us-ascii?Q?6PCKpjY5aKySDmYLDh9NR7sorxnkn/o3mJH9W5pW?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 4dfeccf4-9731-4d0b-51f6-08dc4ed4fd6d
X-MS-Exchange-CrossTenant-AuthSource: CH3PR11MB8660.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Mar 2024 03:13:07.2845
 (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: dgBQGtNxWkM+PujbBHTkXSr50hbxkpNo3xhQYZPQJuMX4QjFk0wlO1Diq7vAO656DzaiRl3bC9tWwH7xjPJwLw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR11MB6392
X-OriginatorOrg: intel.com

>+#if IS_ENABLED(CONFIG_HYPERV)
>+static int vt_flush_remote_tlbs(struct kvm *kvm);
>+#endif
>+
> static __init int vt_hardware_setup(void)
> {
> 	int ret;
>@@ -49,11 +53,29 @@ static __init int vt_hardware_setup(void)
> 		pr_warn_ratelimited("TDX requires mmio caching.  Please enable mmio caching for TDX.\n");
> 	}
> 
>+#if IS_ENABLED(CONFIG_HYPERV)
>+	/*
>+	 * TDX KVM overrides flush_remote_tlbs method and assumes
>+	 * flush_remote_tlbs_range = NULL that falls back to
>+	 * flush_remote_tlbs.  Disable TDX if there are conflicts.
>+	 */
>+	if (vt_x86_ops.flush_remote_tlbs ||
>+	    vt_x86_ops.flush_remote_tlbs_range) {
>+		enable_tdx = false;
>+		pr_warn_ratelimited("TDX requires baremetal. Not Supported on VMM guest.\n");
>+	}
>+#endif
>+
> 	enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
> 	if (enable_tdx)
> 		vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size,
> 					   sizeof(struct kvm_tdx));
> 
>+#if IS_ENABLED(CONFIG_HYPERV)
>+	if (enable_tdx)
>+		vt_x86_ops.flush_remote_tlbs = vt_flush_remote_tlbs;

Is this hook necessary/beneficial to TDX?

if no, we can leave .flush_remote_tlbs as NULL. if yes, we should do:

struct kvm_x86_ops {
..
#if IS_ENABLED(CONFIG_HYPERV) || IS_ENABLED(TDX...)
	int  (*flush_remote_tlbs)(struct kvm *kvm);
	int  (*flush_remote_tlbs_range)(struct kvm *kvm, gfn_t gfn,
					gfn_t nr_pages);
#endif