linux-kernel - Re: [PATCH v11 19/20] x86/mce: Improve error log of kernel space TDX #MC due to erratum

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Date:   Mon, 5 Jun 2023 10:13:23 +0800
From:   Xiaoyao Li <xiaoyao.li@...el.com>
To:     Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     linux-mm@...ck.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, tony.luck@...el.com,
        peterz@...radead.org, tglx@...utronix.de, seanjc@...gle.com,
        pbonzini@...hat.com, david@...hat.com, dan.j.williams@...el.com,
        rafael.j.wysocki@...el.com, ying.huang@...el.com,
        reinette.chatre@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, bagasdotme@...il.com,
        sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v11 19/20] x86/mce: Improve error log of kernel space TDX
 #MC due to erratum

On 6/4/2023 10:27 PM, Kai Huang wrote:
> == Problem ==
> 
> A partial write to a TDX private memory cacheline will silently "poison"
> the line.  Subsequent reads will consume the poison and generate a
> machine check.  According to the TDX hardware spec, neither of these
> things should have happened.

The expectation is that write to TDX private memory with HKID 0 doesn't 
poison the cache line. However, a partial write with HKID 0 does poison 
the cache line. This is the erratum, right?

> To add insult to injury, the Linux machine code will present these as a
> literal "Hardware error" when they were, in fact, a software-triggered
> issue.