[PATCH v10 02/15] FWU: Add FWU metadata structure and driver for accessing metadata

[Jassi Brar]

On Thu, Sep 15, 2022 at 3:15 AM Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
....
> +/**
> + * @mdata_check: check the validity of the FWU metadata partitions
> + * @get_mdata() - Get a FWU metadata copy
> + * @update_mdata() - Update the FWU metadata copy
> + */
> +struct fwu_mdata_ops {
> +       /**
> +        * mdata_check() - Check if the FWU metadata is valid
> +        * @dev:        FWU device
> +        *
> +        * Validate both copies of the FWU metadata. If one of the copies
> +        * has gone bad, restore it from the other bad copy.
> +        *
> +        * Return: 0 if OK, -ve on error
> +        */
> +       int (*mdata_check)(struct udevice *dev);
>
Like get_mdata and update_mdata, maybe  check_mdata too ?

.....
> +/**
> + * fwu_get_active_index() - Get active_index from the FWU metadata
> + * @active_idxp: active_index value to be read
> + *
> + * Read the active_index field from the FWU metadata and place it in
> + * the variable pointed to be the function argument.
> + *
> + * Return: 0 if OK, -ve on error
> + *
> + */
> +int fwu_get_active_index(u32 *active_idxp);
> +
> +/**
> + * fwu_update_active_index() - Update active_index from the FWU metadata
> + * @active_idx: active_index value to be updated
> + *
> + * Update the active_index field in the FWU metadata
> + *
> + * Return: 0 if OK, -ve on error
> + *
> + */
> +int fwu_update_active_index(uint active_idx);
>
maybe  fwu_set_active_index  ? just like fwu_get_active_index

.....
> +/**
> + * fwu_revert_boot_index() - Revert the active index in the FWU metadata
> + *
> + * Revert the active_index value in the FWU metadata, by swapping the values
> + * of active_index and previous_active_index in both copies of the
> + * FWU metadata.
> + *
> + * Return: 0 if OK, -ve on error
> + *
> + */
> +int fwu_revert_boot_index(void)
> +{
> +       int ret;
> +       u32 cur_active_index;
> +       struct udevice *dev;
> +       struct fwu_mdata mdata = { 0 };
> +
> +       ret = fwu_get_dev_mdata(&dev, &mdata);
> +       if (ret)
> +               return ret;
> +
> +       /*
> +        * Swap the active index and previous_active_index fields
> +        * in the FWU metadata
> +        */
> +       cur_active_index = mdata.active_index;
> +       mdata.active_index = mdata.previous_active_index;
> +       mdata.previous_active_index = cur_active_index;
>
This may cause problems.
We are reverting because active_index does not work, and here we set
it to previous_active_index which is supposed to mean "last good
index".
 Also this logic assumes a 2-banks setup, and is obviously incorrect
for >2 banks where the previous_active_index should point to
"boot_index minus 2" bank (but of course there is no guarantee that
that bank is preserved still).
 So either previous_active_index be left changed OR we also copy the
previous bank to active bank before the swap.

.....
> +/**
> + * fwu_accept_image() - Set the Acceptance bit for the image
> + * @img_type_id: GUID of the image type for which the accepted bit is to be
> + *               cleared
> + * @bank: Bank of which the image's Accept bit is to be set
> + *
> + * Set the accepted bit for the image specified by the img_guid parameter. This
> + * indicates acceptance of image for subsequent boots by some governing component
> + * like OS(or firmware).
> + *
> + * Return: 0 if OK, -ve on error
> + *
> + */
> +int fwu_accept_image(efi_guid_t *img_type_id, u32 bank)
> +{
> +       return fwu_clrset_image_accept(img_type_id, bank,
> +                                      IMAGE_ACCEPT_SET);
> +}
> +
> +/**
> + * fwu_clear_accept_image() - Clear the Acceptance bit for the image
>
Something more consistent like fwu_image_accepted_clear()  and
fwu_image_accepted_set() ?

cheers.