linux-kernel - Re: [PATCH v14 06/23] x86/virt/tdx: Add SEAMCALL error printing for module initialization

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Message-ID: <19f8e93e-62c4-485c-a7c3-f29740fc3eca@linux.intel.com>
Date:   Wed, 18 Oct 2023 07:17:12 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     x86@...nel.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, peterz@...radead.org,
        tony.luck@...el.com, tglx@...utronix.de, bp@...en8.de,
        mingo@...hat.com, hpa@...or.com, seanjc@...gle.com,
        pbonzini@...hat.com, rafael@...nel.org, david@...hat.com,
        dan.j.williams@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, ying.huang@...el.com, chao.gao@...el.com,
        nik.borisov@...e.com, bagasdotme@...il.com, sagis@...gle.com,
        imammedo@...hat.com
Subject: Re: [PATCH v14 06/23] x86/virt/tdx: Add SEAMCALL error printing for
 module initialization



On 10/17/2023 3:14 AM, Kai Huang wrote:
> The SEAMCALLs involved during the TDX module initialization are not
> expected to fail.  In fact, they are not expected to return any non-zero
> code (except the "running out of entropy error", which can be handled
> internally already).
> 
> Add yet another set of SEAMCALL wrappers, which treats all non-zero
> return code as error, to support printing SEAMCALL error upon failure
> for module initialization.  Note the TDX module initialization doesn't
> use the _saved_ret() variant thus no wrapper is added for it.
> 
> SEAMCALL assembly can also return kernel-defined error codes for three
> special cases: 1) TDX isn't enabled by the BIOS; 2) TDX module isn't
> loaded; 3) CPU isn't in VMX operation.  Whether they can legally happen
> depends on the caller, so leave to the caller to print error message
> when desired.
> 
> Also convert the SEAMCALL error codes to the kernel error codes in the
> new wrappers so that each SEAMCALL caller doesn't have to repeat the
> conversion.
> 
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> 
> v13 -> v14:
>  - Use real functions to replace macros. (Dave)
>  - Moved printing error message for special error code to the caller
>    (internal)
>  - Added Kirill's tag
> 
> v12 -> v13:
>  - New implementation due to TDCALL assembly series.
> 
> ---

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer