linux-kernel - [RFC PATCH 3/3] tpm/tpm_svsm: use send

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Message-ID: <20250311100130.42169-4-sgarzare@redhat.com>
Date: Tue, 11 Mar 2025 11:01:30 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: linux-integrity@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Peter Huewe <peterhuewe@....de>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Stefano Garzarella <sgarzare@...hat.com>
Subject: [RFC PATCH 3/3] tpm/tpm_svsm: use send_recv() op

This driver does not support interrupts, and receiving the response is
synchronous with sending the command.

Let's simplify the driver by implementing the new send_recv() op.

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
Note: this is based on "[PATCH v3 0/4] Enlightened vTPM support for SVSM
on SEV-SNP" series [1].
If we will merge this series before it, we can just ignore this patch
and I'll squash these changes in that series.

[1] https://lore.kernel.org/linux-integrity/20250311094225.35129-1-sgarzare@redhat.com/
---
 drivers/char/tpm/tpm_svsm.c | 46 ++++++++-----------------------------
 1 file changed, 9 insertions(+), 37 deletions(-)

diff --git a/drivers/char/tpm/tpm_svsm.c b/drivers/char/tpm/tpm_svsm.c
index 5540d0227eed..63208313f86e 100644
--- a/drivers/char/tpm/tpm_svsm.c
+++ b/drivers/char/tpm/tpm_svsm.c
@@ -25,60 +25,32 @@ struct tpm_svsm_priv {
 	u8 locality;
 };
 
-static int tpm_svsm_send(struct tpm_chip *chip, u8 *buf, size_t len)
+static int tpm_svsm_send_recv(struct tpm_chip *chip, u8 *buf, size_t buf_len,
+			      size_t cmd_len)
 {
 	struct tpm_svsm_priv *priv = dev_get_drvdata(&chip->dev);
 	int ret;
 
 	ret = svsm_vtpm_fill_cmd_req((struct tpm_send_cmd_req *)priv->buffer,
-				     priv->locality, buf, len);
+				     priv->locality, buf, cmd_len);
 	if (ret)
 		return ret;
 
 	/*
 	 * The SVSM call uses the same buffer for the command and for the
-	 * response, so after this call, the buffer will contain the response
-	 * that can be used by .recv() op.
+	 * response, so after this call, the buffer will contain the response.
 	 */
-	return snp_svsm_vtpm_send_command(priv->buffer);
-}
-
-static int tpm_svsm_recv(struct tpm_chip *chip, u8 *buf, size_t len)
-{
-	struct tpm_svsm_priv *priv = dev_get_drvdata(&chip->dev);
+	ret = snp_svsm_vtpm_send_command(priv->buffer);
+	if (ret)
+		return ret;
 
-	/*
-	 * The internal buffer contains the response after we send the command
-	 * to SVSM.
-	 */
 	return svsm_vtpm_parse_cmd_resp((struct tpm_send_cmd_resp *)priv->buffer,
-					buf, len);
-}
-
-static void tpm_svsm_cancel(struct tpm_chip *chip)
-{
-	/* not supported */
-}
-
-static u8 tpm_svsm_status(struct tpm_chip *chip)
-{
-	return 0;
-}
-
-static bool tpm_svsm_req_canceled(struct tpm_chip *chip, u8 status)
-{
-	return false;
+					buf, buf_len);
 }
 
 static struct tpm_class_ops tpm_chip_ops = {
 	.flags = TPM_OPS_AUTO_STARTUP,
-	.recv = tpm_svsm_recv,
-	.send = tpm_svsm_send,
-	.cancel = tpm_svsm_cancel,
-	.status = tpm_svsm_status,
-	.req_complete_mask = 0,
-	.req_complete_val = 0,
-	.req_canceled = tpm_svsm_req_canceled,
+	.send_recv = tpm_svsm_send_recv,
 };
 
 static int __init tpm_svsm_probe(struct platform_device *pdev)
-- 
2.48.1