linux-kernel - [PATCH v4 4/4] x86/sev: register tpm-svsm platform device

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Message-ID: <20250324104653.138663-5-sgarzare@redhat.com>
Date: Mon, 24 Mar 2025 11:46:49 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Joerg Roedel <jroedel@...e.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Peter Huewe <peterhuewe@....de>,
	Tom Lendacky <thomas.lendacky@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	x86@...nel.org,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	linux-kernel@...r.kernel.org,
	Borislav Petkov <bp@...en8.de>,
	Jason Gunthorpe <jgg@...pe.ca>,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-coco@...ts.linux.dev,
	Claudio Carvalho <cclaudio@...ux.ibm.com>,
	Dov Murik <dovmurik@...ux.ibm.com>,
	Dionna Glaze <dionnaglaze@...gle.com>,
	linux-integrity@...r.kernel.org,
	Stefano Garzarella <sgarzare@...hat.com>
Subject: [PATCH v4 4/4] x86/sev: register tpm-svsm platform device

From: Stefano Garzarella <sgarzare@...hat.com>

SNP platform can provide a vTPM device emulated by SVSM.

The "tpm-svsm" device can be handled by the platform driver added
by the previous commit in drivers/char/tpm/tpm_svsm.c

Register the device unconditionally. The support check (e.g. SVSM, cmd)
is in snp_svsm_vtpm_probe(), keeping all logic in one place.
This function is called during the driver's probe along with other
setup tasks like memory allocation.

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
v4:
- explained better why we register it anyway in the commit message
---
 arch/x86/coco/sev/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 034aab7e76d2..0abcac87af89 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2692,6 +2692,11 @@ static struct platform_device sev_guest_device = {
 	.id		= -1,
 };
 
+static struct platform_device tpm_svsm_device = {
+	.name		= "tpm-svsm",
+	.id		= -1,
+};
+
 static int __init snp_init_platform_device(void)
 {
 	if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
@@ -2700,6 +2705,9 @@ static int __init snp_init_platform_device(void)
 	if (platform_device_register(&sev_guest_device))
 		return -ENODEV;
 
+	if (platform_device_register(&tpm_svsm_device))
+		return -ENODEV;
+
 	pr_info("SNP guest platform device initialized.\n");
 	return 0;
 }
-- 
2.49.0