Message-Id: <20230619092219.2600-1-LinoSanfilippo@gmx.de>
Date:   Mon, 19 Jun 2023 11:22:19 +0200
From:   Lino Sanfilippo <LinoSanfilippo@....de>
To:     peterhuewe@....de, jarkko@...nel.org, jgg@...pe.ca
Cc:     jsnitsel@...hat.com, hdegoede@...hat.com, oe-lkp@...ts.linux.dev,
        lkp@...el.com, peter.ujfalusi@...ux.intel.com,
        peterz@...radead.org, 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, kernel test robot <yujie.liu@...el.com>
Subject: [PATCH 3] tpm,tpm_tis: Disable interrupts after 1000 unhandled IRQs

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

After activation of interrupts for TPM TIS drivers 0-day reports an
interrupt storm on an Inspur NF5180M6 server.

Fix this by detecting the storm and falling back to polling:
Count the number of unhandled interrupts within a 10 ms time interval. In
case that more than 1000 were unhandled deactivate interrupts entirely,
deregister the handler and use polling instead.

Also print a note to point to the tpm_tis_dmi_table.

Since the interrupt deregistration function devm_free_irq() waits for all
interrupt handlers to finish, only trigger a worker in the interrupt
handler and do the unregistration in the worker to avoid a deadlock.

Note: the storm detection logic equals the implementation in
note_interrupt() which uses timestamps and counters stored in struct
irq_desc. Since this structure is private to the generic interrupt core
the TPM TIS core uses its own timestamps and counters. Furthermore the TPM
interrupt handler always returns IRQ_HANDLED to prevent the generic
interrupt core from processing the interrupt storm.

Reported-by: kernel test robot <yujie.liu@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202305041325.ae8b0c43-yujie.liu@intel.com/
Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Lino Sanfilippo <l.sanfilippo@...bus.com>
---
 drivers/char/tpm/tpm_tis_core.c | 117 ++++++++++++++++++++++++++++----
 drivers/char/tpm/tpm_tis_core.h |   4 ++
 2 files changed, 106 insertions(+), 15 deletions(-)

Changes to v2:
- use define for max number of unhandles irqs(requested by Jarko)
- rename intmask to int_mask (requested by Jarko)
- rephrased short summary (requested by Jarko)
- rename disable_interrupts to tpm_tis_disable_interrupts (requested by Jarko)
- print info message concerning adding an entry to tpm_tis_dmi_table
  (suggested by Jerry)
- amended commit message
- handle failure of locality request by returning IRQ_NONE
- dont take and release locality in __tpm_tis_disable_interrupts but in its
caller

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 558144fa707a..d42537b985c5 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -24,9 +24,12 @@
 #include <linux/wait.h>
 #include <linux/acpi.h>
 #include <linux/freezer.h>
+#include <linux/dmi.h>
 #include "tpm.h"
 #include "tpm_tis_core.h"
 
+#define TPM_TIS_MAX_UNHANDLED_IRQS	1000
+
 static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
 
 static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
@@ -468,25 +471,29 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 	return rc;
 }
 
-static void disable_interrupts(struct tpm_chip *chip)
+static void __tpm_tis_disable_interrupts(struct tpm_chip *chip)
+{
+	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	u32 int_mask = 0;
+
+	tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &int_mask);
+	int_mask &= ~TPM_GLOBAL_INT_ENABLE;
+	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), int_mask);
+
+	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
+}
+
+static void tpm_tis_disable_interrupts(struct tpm_chip *chip)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
-	u32 intmask;
-	int rc;
 
 	if (priv->irq == 0)
 		return;
 
-	rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
-	if (rc < 0)
-		intmask = 0;
-
-	intmask &= ~TPM_GLOBAL_INT_ENABLE;
-	rc = tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
+	__tpm_tis_disable_interrupts(chip);
 
 	devm_free_irq(chip->dev.parent, priv->irq, chip);
 	priv->irq = 0;
-	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
 }
 
 /*
@@ -552,7 +559,7 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	if (!test_bit(TPM_TIS_IRQ_TESTED, &priv->flags))
 		tpm_msleep(1);
 	if (!test_bit(TPM_TIS_IRQ_TESTED, &priv->flags))
-		disable_interrupts(chip);
+		tpm_tis_disable_interrupts(chip);
 	set_bit(TPM_TIS_IRQ_TESTED, &priv->flags);
 	return rc;
 }
@@ -752,6 +759,71 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
 	return status == TPM_STS_COMMAND_READY;
 }
 
+static irqreturn_t tpm_tis_reenable_polling(struct tpm_chip *chip)
+{
+	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	const char *product;
+	const char *vendor;
+
+	dev_warn(&chip->dev, FW_BUG
+		 "TPM interrupt storm detected, polling instead\n");
+
+	vendor = dmi_get_system_info(DMI_SYS_VENDOR);
+	product = dmi_get_system_info(DMI_PRODUCT_VERSION);
+
+	if (vendor && product) {
+		dev_info(&chip->dev,
+			"Consider adding the following entry to tpm_tis_dmi_table:\n");
+		dev_info(&chip->dev, "\tDMI_SYS_VENDOR: %s\n", vendor);
+		dev_info(&chip->dev, "\tDMI_PRODUCT_VERSION: %s\n", product);
+	}
+
+	if (tpm_tis_request_locality(chip, 0) != 0)
+		return IRQ_NONE;
+
+	__tpm_tis_disable_interrupts(chip);
+	tpm_tis_relinquish_locality(chip, 0);
+
+	/*
+	 * devm_free_irq() must not be called from within the interrupt handler,
+	 * since this function waits for running handlers to finish and thus it
+	 * would deadlock. Instead trigger a worker that takes care of the
+	 * unregistration.
+	 */
+	schedule_work(&priv->free_irq_work);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tpm_tis_check_for_interrupt_storm(struct tpm_chip *chip)
+{
+	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	irqreturn_t irqret = IRQ_HANDLED;
+
+	/*
+	 * The worker to free the TPM interrupt (free_irq_work) may already
+	 * be scheduled, so make sure it is not scheduled again.
+	 */
+	if (!(chip->flags & TPM_CHIP_FLAG_IRQ))
+		return IRQ_HANDLED;
+
+	if (time_after(jiffies, priv->last_unhandled_irq + HZ/10))
+		priv->unhandled_irqs = 1;
+	else
+		priv->unhandled_irqs++;
+
+	priv->last_unhandled_irq = jiffies;
+
+	if (priv->unhandled_irqs > TPM_TIS_MAX_UNHANDLED_IRQS)
+		irqret = tpm_tis_reenable_polling(chip);
+
+	/*
+	 * Prevent the genirq code from starting its own interrupt storm
+	 * handling by always reporting that the interrupt was handled.
+	 */
+	return irqret;
+}
+
 static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 {
 	struct tpm_chip *chip = dev_id;
@@ -761,10 +833,10 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 
 	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
 	if (rc < 0)
-		return IRQ_NONE;
+		goto unhandled;
 
 	if (interrupt == 0)
-		return IRQ_NONE;
+		goto unhandled;
 
 	set_bit(TPM_TIS_IRQ_TESTED, &priv->flags);
 	if (interrupt & TPM_INTF_DATA_AVAIL_INT)
@@ -780,10 +852,13 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 	rc = tpm_tis_write32(priv, TPM_INT_STATUS(priv->locality), interrupt);
 	tpm_tis_relinquish_locality(chip, 0);
 	if (rc < 0)
-		return IRQ_NONE;
+		goto unhandled;
 
 	tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
 	return IRQ_HANDLED;
+
+unhandled:
+	return tpm_tis_check_for_interrupt_storm(chip);
 }
 
 static void tpm_tis_gen_interrupt(struct tpm_chip *chip)
@@ -804,6 +879,15 @@ static void tpm_tis_gen_interrupt(struct tpm_chip *chip)
 		chip->flags &= ~TPM_CHIP_FLAG_IRQ;
 }
 
+static void tpm_tis_free_irq_func(struct work_struct *work)
+{
+	struct tpm_tis_data *priv = container_of(work, typeof(*priv), free_irq_work);
+	struct tpm_chip *chip = priv->chip;
+
+	devm_free_irq(chip->dev.parent, priv->irq, chip);
+	priv->irq = 0;
+}
+
 /* Register the IRQ and issue a command that will cause an interrupt. If an
  * irq is seen then leave the chip setup for IRQ operation, otherwise reverse
  * everything and leave in polling mode. Returns 0 on success.
@@ -816,6 +900,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
 	int rc;
 	u32 int_status;
 
+	INIT_WORK(&priv->free_irq_work, tpm_tis_free_irq_func);
 
 	rc = devm_request_threaded_irq(chip->dev.parent, irq, NULL,
 				       tis_int_handler, IRQF_ONESHOT | flags,
@@ -918,6 +1003,7 @@ void tpm_tis_remove(struct tpm_chip *chip)
 		interrupt = 0;
 
 	tpm_tis_write32(priv, reg, ~TPM_GLOBAL_INT_ENABLE & interrupt);
+	flush_work(&priv->free_irq_work);
 
 	tpm_tis_clkrun_enable(chip, false);
 
@@ -1021,6 +1107,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	chip->timeout_b = msecs_to_jiffies(TIS_TIMEOUT_B_MAX);
 	chip->timeout_c = msecs_to_jiffies(TIS_TIMEOUT_C_MAX);
 	chip->timeout_d = msecs_to_jiffies(TIS_TIMEOUT_D_MAX);
+	priv->chip = chip;
 	priv->timeout_min = TPM_TIMEOUT_USECS_MIN;
 	priv->timeout_max = TPM_TIMEOUT_USECS_MAX;
 	priv->phy_ops = phy_ops;
@@ -1179,7 +1266,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 			rc = tpm_tis_request_locality(chip, 0);
 			if (rc < 0)
 				goto out_err;
-			disable_interrupts(chip);
+			tpm_tis_disable_interrupts(chip);
 			tpm_tis_relinquish_locality(chip, 0);
 		}
 	}
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 610bfadb6acf..b1a169d7d1ca 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -91,11 +91,15 @@ enum tpm_tis_flags {
 };
 
 struct tpm_tis_data {
+	struct tpm_chip *chip;
 	u16 manufacturer_id;
 	struct mutex locality_count_mutex;
 	unsigned int locality_count;
 	int locality;
 	int irq;
+	struct work_struct free_irq_work;
+	unsigned long last_unhandled_irq;
+	unsigned int unhandled_irqs;
 	unsigned int int_mask;
 	unsigned long flags;
 	void __iomem *ilb_base_addr;

base-commit: 45a3e24f65e90a047bef86f927ebdc4c710edaa1
-- 
2.40.1

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