LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Stefan Berger <stefanb@linux.vnet.ibm.com>
To: jarkko@kernel.org
Cc: peterhuewe@gmx.de, jgg@ziepe.ca, linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Stefan Berger <stefanb@linux.ibm.com>,
	Nayna Jain <nayna@linux.ibm.com>,
	George Wilson <gcwilson@linux.ibm.com>,
	Nageswara R Sastry <rnsastry@linux.ibm.com>
Subject: [PATCH v3 2/2] tpm: ibmvtpm: Avoid error message when process gets signal while waiting
Date: Thu,  5 Aug 2021 17:52:56 -0400	[thread overview]
Message-ID: <20210805215256.1293987-3-stefanb@linux.vnet.ibm.com> (raw)
In-Reply-To: <20210805215256.1293987-1-stefanb@linux.vnet.ibm.com>

From: Stefan Berger <stefanb@linux.ibm.com>

When rngd is run as root then lots of these types of message will appear
in the kernel log if the TPM has been configured to provide random bytes:

[ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4

The issue is caused by the following call that is interrupted while
waiting for the TPM's response.

sig = wait_event_interruptible(ibmvtpm->wq,
                        (ibmvtpm->tpm_status & TPM_STATUS_BUSY) == 0);

Rather than waiting for the response in the low level driver, have it use
the polling loop in tpm_try_transmit() that uses a command's duration to
poll until a result has been returned by the TPM, thus ending when the
timeout has occurred but not responding to signals and ctrl-c anymore. To
stay in this polling loop extend tpm_ibmvtpm_status() to return
TPM_STATUS_BUSY for as long as the vTPM is busy. Since the loop requires
the TPM's timeouts, get them now using tpm_get_timeouts() after setting
the TPM2 version flag on the chip.

To recreat the resolved issue start rngd like this:

sudo rngd -r /dev/hwrng -t
sudo rngd -r /dev/tpm0 -t

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1981473
Fixes: 6674ff145eef ("tpm_ibmvtpm: properly handle interrupted packet receptions")
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: George Wilson <gcwilson@linux.ibm.com>
Reported-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

---
v3L
 - split for renaming of tpm_processing_cmd

v2:
 - reworded commit text
---
 drivers/char/tpm/tpm_ibmvtpm.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index cd6457061a2e..5d795866b483 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -106,18 +106,12 @@ static int tpm_ibmvtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
 	u16 len;
-	int sig;
 
 	if (!ibmvtpm->rtce_buf) {
 		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
 		return 0;
 	}
 
-	sig = wait_event_interruptible(ibmvtpm->wq,
-				(ibmvtpm->tpm_status & TPM_STATUS_BUSY) == 0);
-	if (sig)
-		return -EINTR;
-
 	len = ibmvtpm->res_len;
 
 	if (count < len) {
@@ -271,7 +265,9 @@ static void tpm_ibmvtpm_cancel(struct tpm_chip *chip)
 
 static u8 tpm_ibmvtpm_status(struct tpm_chip *chip)
 {
-	return 0;
+	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
+
+	return ibmvtpm->tpm_status;
 }
 
 /**
@@ -459,7 +455,7 @@ static const struct tpm_class_ops tpm_ibmvtpm = {
 	.send = tpm_ibmvtpm_send,
 	.cancel = tpm_ibmvtpm_cancel,
 	.status = tpm_ibmvtpm_status,
-	.req_complete_mask = 0,
+	.req_complete_mask = TPM_STATUS_BUSY,
 	.req_complete_val = 0,
 	.req_canceled = tpm_ibmvtpm_req_canceled,
 };
@@ -690,8 +686,15 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
 		goto init_irq_cleanup;
 	}
 
-	if (!strcmp(id->compat, "IBM,vtpm20")) {
+
+	if (!strcmp(id->compat, "IBM,vtpm20"))
 		chip->flags |= TPM_CHIP_FLAG_TPM2;
+
+	rc = tpm_get_timeouts(chip);
+	if (rc)
+		goto init_irq_cleanup;
+
+	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
 		rc = tpm2_get_cc_attrs_tbl(chip);
 		if (rc)
 			goto init_irq_cleanup;
-- 
2.31.1


      parent reply	other threads:[~2021-08-05 21:53 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 21:52 [PATCH v3 0/2] " Stefan Berger
2021-08-05 21:52 ` [PATCH v3 1/2] tpm: ibmvtpm: Rename tpm_process_cmd to tpm_status and define flag Stefan Berger
2021-08-06 11:25   ` Jarkko Sakkinen
2021-08-06 12:08     ` Stefan Berger
2021-08-09  4:27       ` Jarkko Sakkinen
2021-08-05 21:52 ` Stefan Berger [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210805215256.1293987-3-stefanb@linux.vnet.ibm.com \
    --to=stefanb@linux.vnet.ibm.com \
    --cc=gcwilson@linux.ibm.com \
    --cc=jarkko@kernel.org \
    --cc=jgg@ziepe.ca \
    --cc=linux-integrity@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=nayna@linux.ibm.com \
    --cc=peterhuewe@gmx.de \
    --cc=rnsastry@linux.ibm.com \
    --cc=stefanb@linux.ibm.com \
    --subject='Re: [PATCH v3 2/2] tpm: ibmvtpm: Avoid error message when process gets signal while waiting' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).