Re: [PATCH v2] virt: tdx-guest: Add Quote generation support using TSM_REPORTS

[Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 9/20/2023 6:16 AM, Kirill A . Shutemov wrote:
>> +static u8 *tdx_report_new(const struct tsm_desc *desc, void *data, size_t *outblob_len)
>> +{
>> +	struct tdx_quote_buf *quote_buf = quote_data;
>> +	int ret;
>> +	u8 *buf;
>> +	u64 err;
>> +
>> +	if (mutex_lock_interruptible(&quote_lock))
>> +		return ERR_PTR(-EINTR);
>> +
>> +	/*
>> +	 * If the previous request is timedout or interrupted, and the
>> +	 * Quote buf status is still in GET_QUOTE_IN_FLIGHT (owned by
>> +	 * VMM), don't permit any new request.
>> +	 */
>> +	if (quote_buf->status == GET_QUOTE_IN_FLIGHT) {
>> +		ret = -EBUSY;
>> +		goto done;
>> +	}
>> +
>> +	if (desc->inblob_len != TDX_REPORTDATA_LEN) {
>> +		ret = -EINVAL;
>> +		goto done;
>> +	}
>> +
>> +	/* TDX attestation only supports default format request */
>> +	if (desc->outblob_format != TSM_FORMAT_DEFAULT) {
>> +		ret = -EINVAL;
>> +		goto done;
>> +	}
>> +
>> +	u8 *reportdata __free(kfree) = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
> __free() is new to me. Good to know.
> 
> But are we okay now with declaring variables in the middle of the
> function? Any reason we can't do at the top?

Declaring variables at the top is no longer a hard requirement. The main reason
for declaring it here is to use __free cleanup function. If we use top
declaration, then we have free it manually.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer