From: Dave Hansen <dave.hansen@intel.com>
To: Binbin Wu <binbin.wu@linux.intel.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org
Cc: pbonzini@redhat.com, seanjc@google.com, kas@kernel.org,
rick.p.edgecombe@intel.com, vishal.l.verma@intel.com,
xiaoyao.li@intel.com, chao.gao@intel.com
Subject: Re: [PATCH 1/2] KVM: TDX: Allow TDs to read MSR_IA32_PLATFORM_ID
Date: Tue, 28 Apr 2026 11:49:24 -0700 [thread overview]
Message-ID: <0fa94f46-4cd8-4e28-a080-1517fccb1578@intel.com> (raw)
In-Reply-To: <20260428024746.1040531-2-binbin.wu@linux.intel.com>
On 4/27/26 19:47, Binbin Wu wrote:
> Linux kernel reads MSR_IA32_PLATFORM_ID during init since commit
> d8630b67ca1e ("x86/cpu: Add platform ID to CPU info structure"). KVM
> already supports this MSR on read for normal VMs by returning 0.
> Without support for this MSR, TDs get unchecked MSR access errors.
NAK from me on this.
The platform ID is used for one thing and one thing only: microcode
updates. Those updates are solely the domain of the bare-metal OS.
The (guest) kernel code that's even trying to touch this MSR is buggy
and insane. We need to turn that code it off when
X86_FEATURE_HYPERVISOR==1. There's already a patch floating around to do
that.
Please don't add more smoke and mirrors.
next prev parent reply other threads:[~2026-04-28 18:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-28 2:47 [PATCH 0/2] Fix MSR_IA32_PLATFORM_ID access for TDX guests Binbin Wu
2026-04-28 2:47 ` [PATCH 1/2] KVM: TDX: Allow TDs to read MSR_IA32_PLATFORM_ID Binbin Wu
2026-04-28 5:31 ` Xiaoyao Li
2026-04-28 11:44 ` Chao Gao
2026-04-28 16:30 ` Sean Christopherson
2026-04-28 18:31 ` Edgecombe, Rick P
2026-04-28 18:44 ` Sean Christopherson
2026-04-28 19:28 ` Edgecombe, Rick P
2026-04-28 18:49 ` Dave Hansen [this message]
2026-04-28 2:47 ` [PATCH 2/2] x86/cpu: Skip reading MSR_IA32_PLATFORM_ID in virtualized environment Binbin Wu
2026-04-28 6:01 ` Xiaoyao Li
2026-04-28 9:57 ` Binbin Wu
2026-04-28 18:54 ` Edgecombe, Rick P
2026-04-28 19:13 ` Dave Hansen
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