On Thu, May 25, 2017 at 04:32:50PM -0400, Stefan Berger wrote:

On 05/25/2017 04:09 PM, Jason Gunthorpe wrote:

quoted

On Thu, May 25, 2017 at 04:04:24PM -0400, Stefan Berger wrote:

quoted

On 05/25/2017 11:50 AM, Jason Gunthorpe wrote:

quoted

On Thu, May 25, 2017 at 09:12:36AM -0400, Stefan Berger wrote:

quoted

The tpm2_shutdown does not work with the VTPM proxy driver since the
function only gets called when the backend file descriptor is already
closed and at this point no data can be sent anymore. A proper shutdown
would have to be initated by a user space application, such as a container
management stack, that sends the command via the character device before
terminating the TPM emulator.

To avoid the tpm2_shutdown we introduce a TPM_CHIP_FLAG_NO_SHUTDOWN flag
that only the VTPM proxy driver sets. This also avoids misleading kernel
log messages.

This seems strange to me..

Why isn't ops null if the fd has gone away?

What is the call flow that hits this?

In this function here.

static void tpm_del_char_device(struct tpm_chip *chip)
{
     cdev_device_del(&chip->cdev, &chip->dev);

     /* Make the chip unavailable. */
     mutex_lock(&idr_lock);
     idr_replace(&dev_nums_idr, NULL, chip->dev_num);
     mutex_unlock(&idr_lock);

     /* Make the driver uncallable. */
     down_write(&chip->ops_sem);
     if (chip->flags & TPM_CHIP_FLAG_TPM2)
         tpm2_shutdown(chip, TPM2_SU_CLEAR);
     chip->ops = NULL;
     up_write(&chip->ops_sem);
}

The request cannot be deliver because the anonymous fd has been closed
already.

The driver must always be able to process requests until
tpm_del_char_device completes, so this is triggering an existing bug
in vtpm. This change in core behvior is not going to fix the bug.

eg a request from sysfs/etc could come in between vtpm fd closure and
tpm_del_char_device, and it still must be handled properly.

I guess you need to have transmit command fail fast once the fd is
closed.

It doesn't hang. Everything is torn down immediately. What is primarily
annoying are these two log messages:
tpm tpm0: tpm_transmit: tpm_send: error -32
tpm tpm0: transmit returned -32 while stopping the TPM


    Stefan

It's been a while since I've looked into vtpm code. Why was fd closed
before the above? I can go this through myself once I'm back in Finland
next week. Just have forgotten this detail and do not have time to study
this right now.

/Jarkko
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