linux-kernel - [PATCH] tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm

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Message-Id: <20200227155003.592321-1-gcwilson@linux.ibm.com>
Date:   Thu, 27 Feb 2020 10:50:03 -0500
From:   George Wilson <gcwilson@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     Alexey Kardashevskiy <aik@...abs.ru>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-kernel@...r.kernel.org,
        George Wilson <gcwilson@...ux.ibm.com>,
        Linh Pham <phaml@...ibm.com>
Subject: [PATCH] tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm_send()

tpm_ibmvtpm_send() can fail during LPM resume with an H_CLOSED return
from ibmvtpm_send_crq().  The PAPR says, 'The “partner partition
suspended” transport event disables the associated CRQ such that any
H_SEND_CRQ hcall() to the associated CRQ returns H_Closed until the CRQ
has been explicitly enabled using the H_ENABLE_CRQ hcall.' This patch
adds a check in tpm_ibmvtpm_send() for an H_CLOSED return from
ibmvtpm_send_crq() and in that case calls tpm_ibmvtpm_resume() and
retries the ibmvtpm_send_crq() once.

Reported-by: Linh Pham <phaml@...ibm.com>
Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
Signed-off-by: George Wilson <gcwilson@...ux.ibm.com>
---
 drivers/char/tpm/tpm_ibmvtpm.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 78cc52690177..ba3bd503e080 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (C) 2012 IBM Corporation
+ * Copyright (C) 2012-2020 IBM Corporation
  *
  * Author: Ashley Lai <ashleydlai@...il.com>
  *
@@ -25,6 +25,8 @@
 #include "tpm.h"
 #include "tpm_ibmvtpm.h"
 
+static int tpm_ibmvtpm_resume(struct device *dev);
+
 static const char tpm_ibmvtpm_driver_name[] = "tpm_ibmvtpm";
 
 static const struct vio_device_id tpm_ibmvtpm_device_table[] = {
@@ -147,6 +149,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
 	int rc, sig;
+	bool retry = true;
 
 	if (!ibmvtpm->rtce_buf) {
 		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
@@ -179,18 +182,28 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
 	 */
 	ibmvtpm->tpm_processing_cmd = true;
 
+again:
 	rc = ibmvtpm_send_crq(ibmvtpm->vdev,
 			IBMVTPM_VALID_CMD, VTPM_TPM_COMMAND,
 			count, ibmvtpm->rtce_dma_handle);
+
 	if (rc != H_SUCCESS) {
+		/*
+		 * H_CLOSED can be returned after LPM resume.  Call
+		 * tpm_ibmvtpm_resume() to re-enable the CRQ then retry
+		 * ibmvtpm_send_crq() once before failing.
+		 */
+		if (rc == H_CLOSED && retry) {
+			tpm_ibmvtpm_resume(ibmvtpm->dev);
+			retry = false;
+			goto again;
+		}
 		dev_err(ibmvtpm->dev, "tpm_ibmvtpm_send failed rc=%d\n", rc);
-		rc = 0;
 		ibmvtpm->tpm_processing_cmd = false;
-	} else
-		rc = 0;
+	}
 
 	spin_unlock(&ibmvtpm->rtce_lock);
-	return rc;
+	return 0;
 }
 
 static void tpm_ibmvtpm_cancel(struct tpm_chip *chip)
-- 
2.23.0