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 15:16:19 +0200
From: Borislav Petkov <bp@...en8.de>
To: Tom Lendacky <thomas.lendacky@....com>
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 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.

> +	u64 pa;
> +	u32 len;
> +	u8 rsvd[4];
> +};
> +
> +struct svsm_attestation_call {

Can we shorten all "attestion" to "atst" or "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.

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

manifest_ver;

> +	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"

> +	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!

> +{
> +	struct svsm_attestation_call *attest_call;

	struct svsm_attest_call *atst_call;

> +	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.

> +	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;

..

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette