linux-kernel - Re: [RFC PATCH v2 2/6] x86/sev: add SVSM vTPM probe/send

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Message-ID: <6yzzspawrp6lg3m242bcdl5egpdvt6je2kc3cuznnnze7iypc7@4uaonepi7myq>
Date: Mon, 10 Mar 2025 14:59:44 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Borislav Petkov <bp@...en8.de>, Tom Lendacky <thomas.lendacky@....com>
Cc: Jarkko Sakkinen <jarkko@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Claudio Carvalho <cclaudio@...ux.ibm.com>, 
	Peter Huewe <peterhuewe@....de>, x86@...nel.org, Dov Murik <dovmurik@...ux.ibm.com>, 
	linux-coco@...ts.linux.dev, Dionna Glaze <dionnaglaze@...gle.com>, 
	James Bottomley <James.Bottomley@...senpartnership.com>, Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>, 
	Jason Gunthorpe <jgg@...pe.ca>, linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [RFC PATCH v2 2/6] x86/sev: add SVSM vTPM probe/send_command
 functions

On Mon, Mar 10, 2025 at 02:51:33PM +0100, Borislav Petkov wrote:
>On Mon, Mar 10, 2025 at 08:27:37AM -0500, Tom Lendacky wrote:
>> I don't think anything needs to be checked or printed.
>
>Yes.

Ack, I removed the check and the print.

@Boris I also removed `ret` to continue the slimming, so the end
result should be this:

bool snp_svsm_vtpm_probe(void)
{
	struct svsm_call call = {};

	/* The vTPM device is available only if a SVSM is present */
	if (!snp_vmpl)
		return false;

	call.caa = svsm_get_caa();
	call.rax = SVSM_VTPM_CALL(SVSM_VTPM_QUERY);

	if (svsm_perform_call_protocol(&call))
		return false;

	/* Check platform commands contains TPM_SEND_COMMAND - platform command 8 */
	return (call.rcx_out & BIT_ULL(8)) == BIT_ULL(8);
}

Quite nice, thanks for the review!
Stefano