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Message-Id: <20210729161931.3609894-1-stefanb@linux.vnet.ibm.com>
Date: Thu, 29 Jul 2021 12:19:31 -0400
From: Stefan Berger <stefanb@...ux.vnet.ibm.com>
To: jarkko@...nel.org
Cc: peterhuewe@....de, jgg@...pe.ca, linux-integrity@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org,
Stefan Berger <stefanb@...ux.ibm.com>,
Nayna Jain <nayna@...ux.ibm.com>,
George Wilson <gcwilson@...ux.ibm.com>,
Nageswara R Sastry <rnsastry@...ux.ibm.com>
Subject: [PATCH] tpm: ibmvtpm: Avoid error message when process gets signal while waiting
From: Stefan Berger <stefanb@...ux.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 configure 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_processing_cmd);
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 we now extend tpm_ibmvtpm_status() to return
PM_STATUS_BUSY for as long as the vTPM is busy. Since we will need the
timeouts in this loop now we get the TPM 1.2 and TPM 2 timeouts with
tpm_get_timeouts().
Rename the tpm_processing_cmd to tpm_status in ibmvtpm_dev and set the
TPM_STATUS_BUSY flag while the vTPM is busy processing a command.
To recreat the issue start rngd like this:
sudo rngd -r /dev/hwrng -t
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1981473
Fixes: 6674ff145eef ("tpm_ibmvtpm: properly handle interrupted packet receptions")
Cc: Nayna Jain <nayna@...ux.ibm.com>
Cc: George Wilson <gcwilson@...ux.ibm.com>
Reported-by: Nageswara R Sastry <rnsastry@...ux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
---
drivers/char/tpm/tpm_ibmvtpm.c | 31 ++++++++++++++++++-------------
drivers/char/tpm/tpm_ibmvtpm.h | 3 ++-
2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 903604769de9..5d795866b483 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -106,17 +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_processing_cmd);
- if (sig)
- return -EINTR;
-
len = ibmvtpm->res_len;
if (count < len) {
@@ -220,11 +215,12 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
return -EIO;
}
- if (ibmvtpm->tpm_processing_cmd) {
+ if ((ibmvtpm->tpm_status & TPM_STATUS_BUSY)) {
dev_info(ibmvtpm->dev,
"Need to wait for TPM to finish\n");
/* wait for previous command to finish */
- sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
+ sig = wait_event_interruptible(ibmvtpm->wq,
+ (ibmvtpm->tpm_status & TPM_STATUS_BUSY) == 0);
if (sig)
return -EINTR;
}
@@ -237,7 +233,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
* set the processing flag before the Hcall, since we may get the
* result (interrupt) before even being able to check rc.
*/
- ibmvtpm->tpm_processing_cmd = true;
+ ibmvtpm->tpm_status |= TPM_STATUS_BUSY;
again:
rc = ibmvtpm_send_crq(ibmvtpm->vdev,
@@ -255,7 +251,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
goto again;
}
dev_err(ibmvtpm->dev, "tpm_ibmvtpm_send failed rc=%d\n", rc);
- ibmvtpm->tpm_processing_cmd = false;
+ ibmvtpm->tpm_status &= ~TPM_STATUS_BUSY;
}
spin_unlock(&ibmvtpm->rtce_lock);
@@ -269,7 +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;
}
/**
@@ -457,7 +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,
};
@@ -550,7 +548,7 @@ static void ibmvtpm_crq_process(struct ibmvtpm_crq *crq,
case VTPM_TPM_COMMAND_RES:
/* len of the data in rtce buffer */
ibmvtpm->res_len = be16_to_cpu(crq->len);
- ibmvtpm->tpm_processing_cmd = false;
+ ibmvtpm->tpm_status &= ~TPM_STATUS_BUSY;
wake_up_interruptible(&ibmvtpm->wq);
return;
default:
@@ -688,8 +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;
diff --git a/drivers/char/tpm/tpm_ibmvtpm.h b/drivers/char/tpm/tpm_ibmvtpm.h
index b92aa7d3e93e..252f1cccdfc5 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.h
+++ b/drivers/char/tpm/tpm_ibmvtpm.h
@@ -41,7 +41,8 @@ struct ibmvtpm_dev {
wait_queue_head_t wq;
u16 res_len;
u32 vtpm_version;
- bool tpm_processing_cmd;
+ u8 tpm_status;
+#define TPM_STATUS_BUSY (1 << 0) /* vtpm is processing a command */
};
#define CRQ_RES_BUF_SIZE PAGE_SIZE
--
2.31.1
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