[PATCH v2] tpm: ibmvtpm: Avoid error message when process gets signal while waiting
From: Stefan Berger <hidden>
Date: 2021-08-03 20:26:42
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_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 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.
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 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 <redacted>
Reported-by: Nageswara R Sastry <redacted>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
v2:
- reworded commit text
---
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