linux-kernel - Re: [PATCH v2 1/6] x86/tdx: Add TDREPORT TDX Module call support

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Date:   Thu, 8 Jul 2021 07:07:26 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Xiaoyao Li <xiaoyao.li@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/6] x86/tdx: Add TDREPORT TDX Module call support



On 7/8/21 1:16 AM, Xiaoyao Li wrote:
> 
> Sorry I guess I didn't state it clearly during internal review.
> 
> I suggest something like this
> 
> if (ret != TDCALL_SUCCESS) {
>      if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
>          return -EINVAL;
>      else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY)
>          return -EBUSY;
>      else
>          return -EFAULT; //I'm not sure if -EFAULT is proper.
> }

As per current spec, TDCALL_INVALID_OPERAND, TDCALL_OPERAND_BUSY and
0 are the only possible return values. So I have checked for failure case
in if condition and returned success by default. Any reason for specifically
checking for success code ?

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer