RE: [PATCH v2 1/2] thunderbolt: Add support for separating the flush to SPI and authenticate

[<Mario.Limonciello@dell.com>]

> -----Original Message-----
> From: Mika Westerberg <mika.westerberg@linux.intel.com>
> Sent: Tuesday, June 23, 2020 9:33 AM
> To: Limonciello, Mario
> Cc: Andreas Noever; Michael Jamet; Yehezkel Bernat; linux-usb@vger.kernel.org;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2 1/2] thunderbolt: Add support for separating the flush
> to SPI and authenticate
> 
> 
> [EXTERNAL EMAIL]
> 
> On Mon, Jun 22, 2020 at 01:57:57PM -0500, Mario Limonciello wrote:
> > This allows userspace to have a shorter period of time that the device
> > is unusable and to call it at a more convenient time.
> >
> > For example flushing the image may happen while the user is using the
> > machine and authenticating/rebooting may happen while logging out.
> >
> > Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
> > ---
> >  .../ABI/testing/sysfs-bus-thunderbolt         | 11 ++++-
> >  drivers/thunderbolt/nvm.c                     |  1 +
> >  drivers/thunderbolt/switch.c                  | 42 ++++++++++++-------
> >  drivers/thunderbolt/tb.h                      |  2 +
> >  4 files changed, 39 insertions(+), 17 deletions(-)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt
> b/Documentation/ABI/testing/sysfs-bus-thunderbolt
> > index bd504ed323e8..7d0500b4d58a 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-thunderbolt
> > +++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt
> > @@ -178,11 +178,18 @@ KernelVersion:	4.13
> >  Contact:	thunderbolt-software@lists.01.org
> >  Description:	When new NVM image is written to the non-active NVM
> >  		area (through non_activeX NVMem device), the
> > -		authentication procedure is started by writing 1 to
> > -		this file. If everything goes well, the device is
> > +		authentication procedure is started by writing to
> > +		this file.
> > +		If everything goes well, the device is
> >  		restarted with the new NVM firmware. If the image
> >  		verification fails an error code is returned instead.
> >
> > +		This file will accept writing values "1" or "2"
> > +		- Writing "1" will flush the image to the storage
> > +		area and authenticate the image in one action.
> > +		- Writing "2" will run some basic validation on the image
> > +		and flush it to the storage area.
> > +
> >  		When read holds status of the last authentication
> >  		operation if an error occurred during the process. This
> >  		is directly the status value from the DMA configuration
> > diff --git a/drivers/thunderbolt/nvm.c b/drivers/thunderbolt/nvm.c
> > index 4c6aa06ab3d5..29de6d95c6e7 100644
> > --- a/drivers/thunderbolt/nvm.c
> > +++ b/drivers/thunderbolt/nvm.c
> > @@ -100,6 +100,7 @@ int tb_nvm_write_buf(struct tb_nvm *nvm, unsigned int
> offset, void *val,
> >  			return -ENOMEM;
> >  	}
> >
> > +	nvm->flushed = false;
> 
> This means every write invalidates the "flushed" state, right?

Correct.

> 
> >  	nvm->buf_data_size = offset + bytes;
> >  	memcpy(nvm->buf + offset, val, bytes);
> >  	return 0;
> > diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> > index 817c66c7adcf..bbfbfebeee7f 100644
> > --- a/drivers/thunderbolt/switch.c
> > +++ b/drivers/thunderbolt/switch.c
> > @@ -26,6 +26,11 @@ struct nvm_auth_status {
> >  	u32 status;
> >  };
> >
> > +enum nvm_write_ops {
> > +	WRITE_AND_AUTHENTICATE = 1,
> > +	WRITE_ONLY = 2,
> > +};
> > +
> >  /*
> >   * Hold NVM authentication failure status per switch This information
> >   * needs to stay around even when the switch gets power cycled so we
> > @@ -155,8 +160,12 @@ static int nvm_validate_and_write(struct tb_switch *sw)
> >  	}
> >
> >  	if (tb_switch_is_usb4(sw))
> > -		return usb4_switch_nvm_write(sw, 0, buf, image_size);
> > -	return dma_port_flash_write(sw->dma_port, 0, buf, image_size);
> > +		ret = usb4_switch_nvm_write(sw, 0, buf, image_size);
> > +	else
> > +		ret = dma_port_flash_write(sw->dma_port, 0, buf, image_size);
> > +	if (!ret)
> > +		sw->nvm->flushed = true;
> > +	return ret;
> >  }
> >
> >  static int nvm_authenticate_host_dma_port(struct tb_switch *sw)
> > @@ -1488,7 +1497,7 @@ static ssize_t nvm_authenticate_store(struct device
> *dev,
> >  	struct device_attribute *attr, const char *buf, size_t count)
> >  {
> >  	struct tb_switch *sw = tb_to_switch(dev);
> > -	bool val;
> > +	int val;
> >  	int ret;
> >
> >  	pm_runtime_get_sync(&sw->dev);
> > @@ -1504,25 +1513,28 @@ static ssize_t nvm_authenticate_store(struct device
> *dev,
> >  		goto exit_unlock;
> >  	}
> >
> > -	ret = kstrtobool(buf, &val);
> > +	ret = kstrtoint(buf, 10, &val);
> >  	if (ret)
> >  		goto exit_unlock;
> >
> >  	/* Always clear the authentication status */
> >  	nvm_clear_auth_status(sw);
> >
> > -	if (val) {
> > -		if (!sw->nvm->buf) {
> > -			ret = -EINVAL;
> > -			goto exit_unlock;
> > -		}
> > -
> > -		ret = nvm_validate_and_write(sw);
> > -		if (ret)
> > -			goto exit_unlock;
> > +	if (val > 0) {
> > +		if (!sw->nvm->flushed) {
> > +			if (!sw->nvm->buf) {
> > +				ret = -EINVAL;
> > +				goto exit_unlock;
> > +			}
> >
> > -		sw->nvm->authenticating = true;
> > -		ret = nvm_authenticate(sw);
> > +			ret = nvm_validate_and_write(sw);
> > +			if (ret || val == WRITE_ONLY)
> > +				goto exit_unlock;
> > +		}
> > +		if (val == WRITE_AND_AUTHENTICATE) {
> > +			sw->nvm->authenticating = true;
> > +			ret = nvm_authenticate(sw);
> > +		}
> >  	}
> >
> >  exit_unlock:
> > diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> > index 736d1589c31e..43a8ca2eb3d8 100644
> > --- a/drivers/thunderbolt/tb.h
> > +++ b/drivers/thunderbolt/tb.h
> > @@ -42,6 +42,7 @@
> >   *
> >   * The user of this structure needs to handle serialization of possible
> >   * concurrent access.
> > + * @flushed: The image has been flushed to the storage area
> 
> This should go below the @authenticating description.

Oh thanks, I obviously didn't read the actual comments in the merge conflict
when I rebased.  Will fix in a v3.

> 
> >   */
> >  struct tb_nvm {
> >  	struct device *dev;
> > @@ -53,6 +54,7 @@ struct tb_nvm {
> >  	void *buf;
> >  	size_t buf_data_size;
> >  	bool authenticating;
> > +	bool flushed;
> >  };
> >
> >  #define TB_SWITCH_KEY_SIZE		32
> > --
> > 2.25.1