Re: [PATCH 1/2] thunderbolt: allow vendor ID override for NVM programming

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Nov 24, 2021 at 05:37:05PM +0100, Francisco Blas Izquierdo Riera (klondike) wrote:
> Currently, the vendor ID reported by the chipset is checked before to
> avoid accidentally programming devices from unsupported vendors with
> a different NVM structure.
> 
> Certain Thunderbolt devices store the vendor ID in the NVM, therefore
> if the NVM has become corrrupted the device will report an invalid
> vendor ID and reflashing will be impossible on GNU/Linux even if the
> device can boot in safe mode.
> 
> This patch adds a new parameter ``switch_nvm_vendor_override`` which
> can be used to override the vendor ID used for detecting the NVM
> structure allowing to reflash (and authenticate) a new, valid
> image on the device.
> 
> Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <klondike@klondike.es>
> ---
> drivers/thunderbolt/switch.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index 3014146081..a7959c3f3f 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -13,6 +13,7 @@
> #include <linux/sched/signal.h>
> #include <linux/sizes.h>
> #include <linux/slab.h>
> +#include <linux/moduleparam.h>
> #include "tb.h"
> @@ -34,6 +35,10 @@ struct nvm_auth_status {
> static LIST_HEAD(nvm_auth_status_cache);
> static DEFINE_MUTEX(nvm_auth_status_lock);
> +static short switch_nvm_vendor_override = -1;
> +module_param(switch_nvm_vendor_override, short, 0440);
> +MODULE_PARM_DESC(switch_nvm_vendor_override, "Override the switch vendor id on the nvm access routines");
> +
> static struct nvm_auth_status *__nvm_get_auth_status(const struct tb_switch *sw)
> {
> struct nvm_auth_status *st;
> @@ -391,7 +396,9 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
> * relax this in the future when we learn other NVM formats.
> */
> if (sw->config.vendor_id != PCI_VENDOR_ID_INTEL &&
> - sw->config.vendor_id != 0x8087) {
> + sw->config.vendor_id != 0x8087 &&
> + switch_nvm_vendor_override != PCI_VENDOR_ID_INTEL &&
> + switch_nvm_vendor_override != 0x8087) {
> dev_info(&sw->dev,
> "NVM format of vendor %#x is not known, disabling NVM upgrade\n",
> sw->config.vendor_id);

Patch is corrupted :(

Anyway, module parameters are from the 1990's and should stay there.
Please use a per-device way to handle this instead, as trying to handle
module parameters is very difficult over time.

thanks,

greg k-h