From: Dave Hansen <dave.hansen@intel.com>
To: Chao Gao <chao.gao@intel.com>,
kvm@vger.kernel.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org, x86@kernel.org
Cc: binbin.wu@linux.intel.com, dave.hansen@linux.intel.com,
djbw@kernel.org, ira.weiny@intel.com, kai.huang@intel.com,
kas@kernel.org, nik.borisov@suse.com, paulmck@kernel.org,
pbonzini@redhat.com, reinette.chatre@intel.com,
rick.p.edgecombe@intel.com, sagis@google.com, seanjc@google.com,
tony.lindgren@linux.intel.com, vannapurve@google.com,
vishal.l.verma@intel.com, yilun.xu@linux.intel.com,
xiaoyao.li@intel.com, yan.y.zhao@intel.com,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v8 18/21] coco/tdx-host: Don't expose P-SEAMLDR features on CPUs with erratum
Date: Thu, 30 Apr 2026 13:09:30 -0700 [thread overview]
Message-ID: <abd48a30-8d51-4a86-b662-b09afb567dc5@intel.com> (raw)
In-Reply-To: <20260427152854.101171-19-chao.gao@intel.com>
On 4/27/26 08:28, Chao Gao wrote:
> Some TDX-capable CPUs have an erratum, as documented in Intel® Trust
> Domain CPU Architectural Extensions (May 2021 edition) Chapter 2.3:
>
> SEAMRET from the P-SEAMLDR clears the current VMCS structure pointed
> to by the current-VMCS pointer. A VMM that invokes the P-SEAMLDR using
> SEAMCALL must reload the current-VMCS, if required, using the VMPTRLD
> instruction.
>
> Clearing the current VMCS behind KVM's back will break KVM.
>
> This erratum is not present when IA32_VMX_BASIC[60] is set. Add a CPU
> bug bit for this erratum and refuse to expose P-SEAMLDR features (e.g.,
> TDX module updates) on affected CPUs.
This seems totally random.
Shouldn't this be way back when can_expose_seamldr() got defined in the
first place?
> +#define X86_BUG_SEAMRET_INVD_VMCS X86_BUG( 1*32+11) /* "seamret_invd_vmcs" SEAMRET from P-SEAMLDR clears the current VMCS */
I find myself wondering if this is worth a bug bit.
next prev parent reply other threads:[~2026-04-30 20:09 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 15:27 [PATCH v8 00/21] Runtime TDX module update support Chao Gao
2026-04-27 15:27 ` [PATCH v8 01/21] x86/virt/tdx: Move low level SEAMCALL helpers out of <asm/tdx.h> Chao Gao
2026-04-27 18:12 ` Vishal Annapurve
2026-04-27 15:27 ` [PATCH v8 02/21] coco/tdx-host: Introduce a "tdx_host" device Chao Gao
2026-04-27 15:27 ` [PATCH v8 03/21] coco/tdx-host: Expose TDX module version Chao Gao
2026-04-27 15:27 ` [PATCH v8 04/21] x86/virt/seamldr: Introduce a wrapper for P-SEAMLDR SEAMCALLs Chao Gao
2026-04-27 15:27 ` [PATCH v8 05/21] x86/virt/seamldr: Add a helper to retrieve P-SEAMLDR information Chao Gao
2026-04-27 15:28 ` [PATCH v8 06/21] coco/tdx-host: Expose P-SEAMLDR information via sysfs Chao Gao
2026-04-27 15:28 ` [PATCH v8 07/21] coco/tdx-host: Implement firmware upload sysfs ABI for TDX module updates Chao Gao
2026-04-29 23:17 ` Dave Hansen
2026-05-06 2:35 ` Chao Gao
2026-04-27 15:28 ` [PATCH v8 08/21] x86/virt/seamldr: Allocate and populate a module update request Chao Gao
2026-04-30 0:45 ` Dave Hansen
2026-04-30 21:23 ` Edgecombe, Rick P
2026-04-30 21:31 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 09/21] x86/virt/seamldr: Introduce skeleton for TDX module updates Chao Gao
2026-04-30 20:03 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 10/21] x86/virt/seamldr: Shut down the current TDX module Chao Gao
2026-04-30 18:52 ` Dave Hansen
2026-05-06 2:56 ` Chao Gao
2026-04-27 15:28 ` [PATCH v8 11/21] x86/virt/tdx: Reset software states during TDX module shutdown Chao Gao
2026-04-30 18:58 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 12/21] x86/virt/seamldr: Install a new TDX module Chao Gao
2026-04-30 19:00 ` Dave Hansen
2026-04-30 21:48 ` Edgecombe, Rick P
2026-04-30 22:29 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 13/21] x86/virt/seamldr: Do TDX per-CPU initialization after module installation Chao Gao
2026-04-27 15:28 ` [PATCH v8 14/21] x86/virt/tdx: Restore TDX module state Chao Gao
2026-04-27 15:28 ` [PATCH v8 15/21] x86/virt/tdx: Refresh TDX module version after update Chao Gao
2026-04-30 19:14 ` Dave Hansen
2026-04-30 21:35 ` Edgecombe, Rick P
2026-04-27 15:28 ` [PATCH v8 16/21] x86/virt/tdx: Reject updates during concurrent TD build Chao Gao
2026-04-30 19:25 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 17/21] x86/virt/seamldr: Abort updates on failure Chao Gao
2026-04-30 20:06 ` Dave Hansen
2026-04-27 15:28 ` [PATCH v8 18/21] coco/tdx-host: Don't expose P-SEAMLDR features on CPUs with erratum Chao Gao
2026-04-30 20:09 ` Dave Hansen [this message]
2026-04-27 15:28 ` [PATCH v8 19/21] x86/virt/tdx: Enable TDX module runtime updates Chao Gao
2026-04-27 15:28 ` [PATCH v8 20/21] coco/tdx-host: Document TDX module update compatibility criteria Chao Gao
2026-04-27 15:28 ` [PATCH v8 21/21] x86/virt/tdx: Document TDX module update Chao Gao
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