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Message-ID: <20210805204447.o43rftv7mo56keir@kernel.org>
Date: Thu, 5 Aug 2021 23:44:47 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Stefan Berger <stefanb@...ux.vnet.ibm.com>
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: Re: [PATCH v2] tpm: ibmvtpm: Avoid error message when process gets
signal while waiting
On Tue, Aug 03, 2021 at 04:26:22PM -0400, Stefan Berger wrote:
> 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 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@...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>
>
> ---
>
> 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
>
>
Please do not do the rename in the bug fix. If you really want to rename,
then this must be split into two commits.
/Jarkko
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