linux-kernel - Re: [PATCH v11 05/20] x86/virt/tdx: Add SEAMCALL infrastructure

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Message-ID: <f51a1ea4-178c-1af7-99bc-865c12780e15@intel.com>
Date:   Thu, 8 Jun 2023 07:05:50 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Huang, Kai" <kai.huang@...el.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     "Luck, Tony" <tony.luck@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v11 05/20] x86/virt/tdx: Add SEAMCALL infrastructure

On 6/7/23 15:56, Huang, Kai wrote:
> It's not just for the "BIOS buggy" case.  The main purpose is to give an error
> message when the caller mistakenly calls tdx_enable().

It's also OK to oops when there's a kernel bug, aka. caller mistake.

> Also, now the machine check handler improvement patch also calls SEAMCALL to get
> a given page's page type.  It's totally legal that a machine check happens when
> the CPU isn't in VMX operation (e.g. KVM isn't loaded), and in fact we use the
> SEAMCALL return value to detect whether CPU is in VMX operation and handles such
> case accordingly.

Listen, I didn't say there wasn't a reason for it.  I said that this
patch lacked the justification.  So, stop throwing things at the wall,
pick the *REAL* reason, and go rewrite the patch, please.