linux-kernel - [PATCH v5 06/10] tpm, tpm_tis: Only handle supported interrupts in wait_for_tpm

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Message-Id: <20220610110846.8307-7-LinoSanfilippo@gmx.de>
Date:   Fri, 10 Jun 2022 13:08:42 +0200
From:   LinoSanfilippo@....de
To:     peterhuewe@....de, jarkko@...nel.org, jgg@...pe.ca
Cc:     stefanb@...ux.vnet.ibm.com, linux@...ewoehner.de,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        l.sanfilippo@...bus.com, LinoSanfilippo@....de, lukas@...ner.de,
        p.rosenberger@...bus.com
Subject: [PATCH v5 06/10] tpm, tpm_tis: Only handle supported interrupts in wait_for_tpm_stat()

From: Lino Sanfilippo <l.sanfilippo@...bus.com>

According to the TPM Interface Specification (TIS) interrupts for
"stsValid" and "commandReady" might not be supported.

Take this into account and only wait for interrupts which are actually in
use in wait_for_tpm_stat(). After that process all the remaining status
changes by polling the status register.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
---
 drivers/char/tpm/tpm_tis_core.c | 46 ++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 2f03fefa1706..028bec44362d 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -53,41 +53,63 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 	long rc;
 	u8 status;
 	bool canceled = false;
+	u8 active_irqs = 0;
+	int ret = 0;
 
 	/* check current status */
 	status = chip->ops->status(chip);
 	if ((status & mask) == mask)
 		return 0;
 
-	stop = jiffies + timeout;
+	/* check what status changes can be handled by irqs */
+	if (priv->irqs_in_use & TPM_INTF_STS_VALID_INT)
+		active_irqs |= TPM_STS_VALID;
 
-	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
+	if (priv->irqs_in_use & TPM_INTF_DATA_AVAIL_INT)
+		active_irqs |= TPM_STS_DATA_AVAIL;
+
+	if (priv->irqs_in_use & TPM_INTF_CMD_READY_INT)
+		active_irqs |= TPM_STS_COMMAND_READY;
+
+	active_irqs &= mask;
+
+	stop = jiffies + timeout;
+	/* process status changes with irq support */
+	if (active_irqs) {
+		ret = -ETIME;
 again:
 		timeout = stop - jiffies;
 		if ((long)timeout <= 0)
 			return -ETIME;
 		rc = wait_event_interruptible_timeout(*queue,
-			wait_for_tpm_stat_cond(chip, mask, check_cancel,
+			wait_for_tpm_stat_cond(chip, active_irqs, check_cancel,
 					       &canceled),
 			timeout);
 		if (rc > 0) {
 			if (canceled)
 				return -ECANCELED;
-			return 0;
+			ret = 0;
 		}
 		if (rc == -ERESTARTSYS && freezing(current)) {
 			clear_thread_flag(TIF_SIGPENDING);
 			goto again;
 		}
-	} else {
-		do {
-			usleep_range(priv->timeout_min,
-				     priv->timeout_max);
-			status = chip->ops->status(chip);
-			if ((status & mask) == mask)
-				return 0;
-		} while (time_before(jiffies, stop));
 	}
+
+	if (ret)
+		return ret;
+
+	mask &= ~active_irqs;
+	if (!mask) /* all done */
+		return 0;
+	/* process status changes without irq support */
+	do {
+		status = chip->ops->status(chip);
+		if ((status & mask) == mask)
+			return 0;
+		usleep_range(priv->timeout_min,
+			     priv->timeout_max);
+	} while (time_before(jiffies, stop));
 	return -ETIME;
 }
 
-- 
2.36.1