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Message-ID: <adc0987a-70f5-4203-c741-978d7d89cf76@linux.intel.com>
Date:   Wed, 12 Oct 2022 16:01:31 -0700
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From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Subject: Re: [PATCH v14 2/3] virt: Add TDX guest driver
To:     Borislav Petkov <bp@alien8.de>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        Shuah Khan <shuah@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Kai Huang <kai.huang@intel.com>,
        Wander Lairson Costa <wander@redhat.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-doc@vger.kernel.org
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 <20220928215535.26527-3-sathyanarayanan.kuppuswamy@linux.intel.com>
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On 10/12/22 8:47 AM, Borislav Petkov wrote:
> On Wed, Sep 28, 2022 at 02:55:34PM -0700, Kuppuswamy Sathyanarayanan wrote:
>> +static long tdx_get_report(void __user *argp)
>> +{
>> +	u8 *reportdata, *tdreport;
>> +	struct tdx_report_req req;
>> +	long ret;
>> +
>> +	if (copy_from_user(&req, argp, sizeof(req)))
>> +		return -EFAULT;
>> +
>> +	/*
>> +	 * Per TDX Module 1.0 specification, section titled
>> +	 * "TDG.MR.REPORT", REPORTDATA length is fixed as
>> +	 * TDX_REPORTDATA_LEN, TDREPORT length is fixed as
>> +	 * TDX_REPORT_LEN, and TDREPORT subtype is fixed as 0.
>> +	 */
>> +	if (req.subtype || req.rpd_len != TDX_REPORTDATA_LEN ||
>> +	    req.tdr_len != TDX_REPORT_LEN)
>> +		return -EINVAL;
>> +
>> +	if (memchr_inv(req.reserved, 0, sizeof(req.reserved)))
> 
> I'm guessing we should issue something here to userspace to let it know
> why the it fails getting the report.

I am fine with adding an error message here. What about the above -EINVAL
case? Do you suggest adding it there as well?

> 
> Otherwise it is starting to look good and boring. :)
> 
> Thx.
> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer