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From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org
Cc:     Jarkko Sakkinen <jarkko@kernel.org>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Peter Huewe <peterhuewe@gmx.de>,
        James Bottomley <James.Bottomley@HansenPartnership.com>,
        Matthew Garrett <mjg59@google.com>,
        Hans de Goede <hdegoede@redhat.com>
Subject: [PATCH] tpm_tis: Disable interrupts if interrupt storm detected
Date:   Mon, 30 Nov 2020 16:23:38 -0700
Message-Id: <20201130232338.106892-1-jsnitsel@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

When enabling the interrupt code for the tpm_tis driver we have
noticed some systems have a bios issue causing an interrupt storm to
occur. The issue isn't limited to a single tpm or system vendor
so keeping a denylist of systems with the issue isn't optimal. Instead
try to detect the problem occurring, disable interrupts, and revert to
polling when it happens.

Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Peter Huewe <peterhuewe@gmx.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Matthew Garrett <mjg59@google.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
---
 drivers/char/tpm/tpm_tis_core.c | 34 +++++++++++++++++++++++++++++++++
 drivers/char/tpm/tpm_tis_core.h |  2 ++
 2 files changed, 36 insertions(+)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 92c51c6cfd1b..19115a628f25 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -24,6 +24,8 @@
 #include <linux/wait.h>
 #include <linux/acpi.h>
 #include <linux/freezer.h>
+#include <linux/workqueue.h>
+#include <linux/kernel_stat.h>
 #include "tpm.h"
 #include "tpm_tis_core.h"
 
@@ -711,13 +713,30 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
 	}
 }
 
+static struct workqueue_struct *tpm_tis_wq;
+static DEFINE_MUTEX(tpm_tis_wq_lock);
+
 static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 {
 	struct tpm_chip *chip = dev_id;
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	static bool check_storm = true;
+	static unsigned int check_start;
 	u32 interrupt;
 	int i, rc;
 
+	if (unlikely(check_storm)) {
+		if (!check_start) {
+			check_start = jiffies_to_msecs(jiffies);
+		} else if ((kstat_irqs(priv->irq) > 1000) &&
+			   (jiffies_to_msecs(jiffies) - check_start < 500)) {
+			check_storm = false;
+			queue_work(tpm_tis_wq, &priv->storm_work);
+		} else if (jiffies_to_msecs(jiffies) - check_start >= 500) {
+			check_storm = false;
+		}
+	}
+
 	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
 	if (rc < 0)
 		return IRQ_NONE;
@@ -943,6 +962,14 @@ static const struct tpm_class_ops tpm_tis = {
 	.clk_enable = tpm_tis_clkrun_enable,
 };
 
+static void tpm_tis_storm_work(struct work_struct *work)
+{
+	struct tpm_tis_data *priv = container_of(work, struct tpm_tis_data, storm_work);
+
+	disable_interrupts(priv->chip);
+	dev_warn(&priv->chip->dev, "Interrupt storm detected, using polling.\n");
+}
+
 int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		      const struct tpm_tis_phy_ops *phy_ops,
 		      acpi_handle acpi_dev_handle)
@@ -959,6 +986,13 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	if (IS_ERR(chip))
 		return PTR_ERR(chip);
 
+	priv->chip = chip;
+	tpm_tis_wq = alloc_workqueue("tpm_tis_wq", WQ_MEM_RECLAIM, 0);
+	if (!tpm_tis_wq)
+		return -ENOMEM;
+
+	INIT_WORK(&priv->storm_work, tpm_tis_storm_work);
+
 #ifdef CONFIG_ACPI
 	chip->acpi_dev_handle = acpi_dev_handle;
 #endif
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 9b2d32a59f67..973297ee2e16 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -95,6 +95,8 @@ struct tpm_tis_data {
 	u16 clkrun_enabled;
 	wait_queue_head_t int_queue;
 	wait_queue_head_t read_queue;
+	struct work_struct storm_work;
+	struct tpm_chip *chip;
 	const struct tpm_tis_phy_ops *phy_ops;
 	unsigned short rng_quality;
 };
-- 
2.27.0