linux-kernel - Re: [PATCH v4 14/15] x86/sev: Extend the config-fs attestation support for an SVSM

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Date: Fri, 31 May 2024 14:03:21 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, linux-coco@...ts.linux.dev,
 svsm-devel@...onut-svsm.dev, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>,
 Dan Williams <dan.j.williams@...el.com>, Michael Roth
 <michael.roth@....com>, Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v4 14/15] x86/sev: Extend the config-fs attestation
 support for an SVSM

On 5/31/24 08:16, Borislav Petkov wrote:
> On Wed, Apr 24, 2024 at 10:58:10AM -0500, Tom Lendacky wrote:
>> +/*
>> + * The SVSM Attestation related structures
>> + */
>> +struct svsm_location_entry {
> 
> "svsm_loc" should be enough.

Ok

> 
>> +	u64 pa;
>> +	u32 len;
>> +	u8 rsvd[4];
>> +};
>> +
>> +struct svsm_attestation_call {
> 
> Can we shorten all "attestion" to "atst" or "attest"?

Will shorten to attest.

> 
>> +	struct svsm_location_entry report_buffer;
>> +	struct svsm_location_entry nonce;
>> +	struct svsm_location_entry manifest_buffer;
>> +	struct svsm_location_entry certificates_buffer;
> 
> report_buf;
> nonce;
> manifest_buf;
> certs_buf;
> 
> Please shorten all those.

Ok.

> 
>> +	/* For attesting a single service */
>> +	u8 service_guid[16];
>> +	u32 service_manifest_version;
> 
> manifest_ver;

Yep.

> 
>> +	u8 rsvd[4];
>> +};
>> +
>>   /*
>>    * SVSM protocol structure
> 
> ...
> 
>> +static void update_attestation_input(struct svsm_call *call, struct svsm_attestation_call *input)
>> +{
>> +	/* If (new) lengths have been returned, propograte them up */
> 
> "propagate"

Fixed.

> 
>> +	if (call->rcx_out != call->rcx)
>> +		input->manifest_buffer.len = call->rcx_out;
>> +
>> +	if (call->rdx_out != call->rdx)
>> +		input->certificates_buffer.len = call->rdx_out;
>> +
>> +	if (call->r8_out != call->r8)
>> +		input->report_buffer.len = call->r8_out;
>> +}
>> +
>> +int snp_issue_svsm_attestation_request(u64 call_id, struct svsm_attestation_call *input)
> 
> This looks like BIOS code. The only thing that's missing is the
> CamelCase. :-)
> 
> int snp_issue_svsm_attest_req(u64 call_id, struct svsm_attest_call *input_call)
> 
> Now that's more like it!

Ok.

> 
>> +{
>> +	struct svsm_attestation_call *attest_call;
> 
> 	struct svsm_attest_call *atst_call;

Ok, I'll use 'ac'

> 
>> +	struct svsm_call call = {};
>> +	unsigned long flags;
>> +	u64 attest_call_pa;
>> +	int ret;
>> +
>> +	if (!vmpl)
>> +		return -EINVAL;
>> +
> 
> ...
> 
>> +static int sev_svsm_report_new(struct tsm_report *report, void *data)
>> +{
>> +	unsigned int report_len, manifest_len, certificates_len;
>> +	void *report_blob, *manifest_blob, *certificates_blob;
> 
> Prose. Shorter pls.

Ok.

Thanks,
Tom

> 
>> +	struct svsm_attestation_call attest_call = {};
>> +	struct tsm_desc *desc = &report->desc;
>> +	unsigned int retry_count;
>> +	unsigned int size;
>> +	bool try_again;
>> +	void *buffer;
>> +	u64 call_id;
>> +	int ret;
> 
> ...
>