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References: <20230420165454.9517-1-jorge.lopez2@hp.com> <20230420165454.9517-6-jorge.lopez2@hp.com>
 <24fb56f9-49c6-432d-8c2f-17df7f7e37b2@t-8ch.de>
In-Reply-To: <24fb56f9-49c6-432d-8c2f-17df7f7e37b2@t-8ch.de>
From:   Jorge Lopez <jorgealtxwork@gmail.com>
Date:   Fri, 5 May 2023 11:09:55 -0500
Message-ID: <CAOOmCE-HR205R2vjyZedDocZLwvMdk7B1w7w9HgdXaypTrBK+A@mail.gmail.com>
Subject: Re: [PATCH v11 05/14] HP BIOSCFG driver - ordered-attributes
To:     thomas@t-8ch.de
Cc:     hdegoede@redhat.com, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Sun, Apr 23, 2023 at 1:55=E2=80=AFAM <thomas@t-8ch.de> wrote:
>
> On 2023-04-20 11:54:45-0500, Jorge Lopez wrote:
> >  .../x86/hp/hp-bioscfg/ordered-attributes.c    | 563 ++++++++++++++++++
> >  1 file changed, 563 insertions(+)
> >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/ordered-attribut=
es.c
> >
> > diff --git a/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c b/=
drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> > new file mode 100644
> > index 000000000000..5e5d540f728d
> > --- /dev/null
> > +++ b/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> > @@ -0,0 +1,563 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Functions corresponding to ordered list type attributes under
> > + * BIOS ORDERED LIST GUID for use with hp-bioscfg driver.
> > + *
> > + *  Copyright (c) 2022 HP Development Company, L.P.
> > + */
> > +
> > +#include "bioscfg.h"
> > +
> > +GET_INSTANCE_ID(ordered_list);
> > +
> > +static ssize_t current_value_show(struct kobject *kobj, struct kobj_at=
tribute *attr, char *buf)
> > +{
> > +
> > +     int instance_id =3D get_ordered_list_instance_id(kobj);
> > +
> > +     if (instance_id < 0)
> > +             return -EIO;
> > +
> > +     return sysfs_emit(buf, "%s\n",
> > +                      bioscfg_drv.ordered_list_data[instance_id].curre=
nt_value);
> > +}
> > +
> > +/*
> > + * validate_ordered_list_value -
> > + * Validate input of current_value against possible values
>
> Does the firmware not also validate this?
>
> If so it may be easier to just let it do so and remove the validations
> from the driver.

Yes.  the firmware validates the data.
Will remove the validation
>
> > + *
> > + * @instance_id: The instance on which input is validated
> > + * @buf: Input value
> > + */
> > +static int validate_ordered_list_values(int instance_id, const char *b=
uf)
> > +{
> > +     int ret =3D 0;
> > +     int found =3D 0;
> > +     char *new_values =3D NULL;
> > +     char *value;
> > +     int elem;
> > +     int elem_found =3D 0;
> > +
> > +     /* Is it a read only attribute */
> > +     if (bioscfg_drv.ordered_list_data[instance_id].common.is_readonly=
)
> > +             return -EIO;
> > +
> > +     new_values =3D kstrdup(buf, GFP_KERNEL);
> > +
> > +     /*
> > +      * Changes to ordered list values require checking that new
> > +      * values are found in the list of elements.
> > +      */
> > +     elem_found =3D 0;
> > +     while (elem_found < bioscfg_drv.ordered_list_data[instance_id].el=
ements_size) {
> > +
> > +             value =3D strsep(&new_values, ",");
>
> The docs say the separator is semicolon.

BIOS reports the current value using ',' as separator instead of ";".

./hp-bioscfg/attributes/UEFI Boot Order/current_value
HDD:M.2:3,HDD:USB:1(Disabled),HDD:M.2:4,HDD:M.2:1,HDD:M.2:2,NETWORK
IPV4:EMBEDDED:1,NETWORK IPV6:EMBEDDED:1,NETWORK
IPV4:EXPANSION:1,NETWORK IPV6:EXPANSION:1

To avoid having to convert from "," to ";" and vice versa, I will
update the documentation to reflect the use of  "'," commas as the
separator

>
> > +             if (value !=3D NULL) {
> > +                     if (!*value)
> > +                             continue;
> > +                     elem_found++;
> > +             }
> > +
> > +             found =3D 0;
> > +             for (elem =3D 0; elem < bioscfg_drv.ordered_list_data[ins=
tance_id].elements_size; elem++) {
> > +                     if (!strcasecmp(bioscfg_drv.ordered_list_data[ins=
tance_id].elements[elem], value)) {
>
> It's surprising that this is case-insensitive.

As validated in earlier reviews,  BIOS rejects strings that do not
match the internal values.

>
> > +                             found =3D 1;
> > +                             break;
> > +                     }
> > +             }
> > +
> > +
> > +             if (!found) {
> > +                     ret =3D -EINVAL;
> > +                     goto out_list_value;
> > +             }
> > +     }
> > +
> > +     if (elem_found =3D=3D bioscfg_drv.ordered_list_data[instance_id].=
elements_size) {
> > +             pr_warn("Number of new values is not equal to number of o=
rdered list elements (%d)\n",
> > +                     bioscfg_drv.ordered_list_data[instance_id].elemen=
ts_size);
> > +             ret =3D -EINVAL;
> > +             goto out_list_value;
> > +     }
> > +
> > +out_list_value:
> > +     kfree(new_values);
> > +     return ret;
> > +}
>
> This algorithm does not seem to validate that different values are
> provided.
>
> So if "possible_values" is "foo,bar,baz" this function would accept
> "foo,foo,foo".
>

BIOS will reject strings such as "foo,foo,foo" when the current value
is "foo,bar,baz".   It is ok to provide a string which items are
ordered differently.  i.e. "baz,bar,foo"
validate_ordered_list_values() function will be removed as indicated earlie=
r.

> > +
> > +/*
> > + * validate_ordered_input() -
> > + * Validate input of current_value against possible values
> > + *
> > + * @instance_id: The instance on which input is validated
> > + * @buf: Input value
> > + */
> > +static int validate_ordered_list_input(int instance_id, const char *bu=
f)
> > +{
> > +     int ret =3D 0;
> > +
> > +     ret =3D validate_ordered_list_values(instance_id, buf);
> > +     if (ret < 0)
> > +             return -EINVAL;
> > +
> > +     /*
> > +      * set pending reboot flag depending on
> > +      * "RequiresPhysicalPresence" value
> > +      */
> > +     if (bioscfg_drv.ordered_list_data[instance_id].common.requires_ph=
ysical_presence)
> > +             bioscfg_drv.pending_reboot =3D true;
> > +
> > +     return ret;
> > +}
> > +
> > +static void update_ordered_list_value(int instance_id, char *attr_valu=
e)
> > +{
> > +     strscpy(bioscfg_drv.ordered_list_data[instance_id].current_value,
> > +             attr_value,
> > +             sizeof(bioscfg_drv.ordered_list_data[instance_id].current=
_value));
> > +}
> > +
> > +ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name_language_code, ordered_l=
ist);
> > +static struct kobj_attribute ordered_list_display_langcode =3D
> > +     __ATTR_RO(display_name_language_code);
> > +
> > +ATTRIBUTE_S_COMMON_PROPERTY_SHOW(display_name, ordered_list);
> > +static struct kobj_attribute ordered_list_display_name =3D
> > +     __ATTR_RO(display_name);
> > +
> > +ATTRIBUTE_PROPERTY_STORE(current_value, ordered_list);
> > +static struct kobj_attribute ordered_list_current_val =3D
> > +     __ATTR_RW_MODE(current_value, 0644);
> > +
> > +
> > +ATTRIBUTE_N_COMMON_PROPERTY_SHOW(prerequisites_size, ordered_list);
> > +static struct kobj_attribute  ordered_list_prerequisites_size_val =3D
> > +     __ATTR_RO(prerequisites_size);
> > +
> > +ATTRIBUTE_V_COMMON_PROPERTY_SHOW(prerequisites, ordered_list);
> > +static struct kobj_attribute  ordered_list_prerequisites_val =3D
> > +     __ATTR_RO(prerequisites);
> > +
> > +ATTRIBUTE_N_PROPERTY_SHOW(elements_size, ordered_list);
> > +static struct kobj_attribute  ordered_list_elements_size_val =3D
> > +     __ATTR_RO(elements_size);
>
> "size" and "length" attributes are fairly useless to userspace.
> They can't be trusted to provide information about another attribute as
> the information can be out of date when the other attribute is read.
>

Prerequisites, prerequisites_size and elements_size will be removed

> > +
> > +ATTRIBUTE_VALUES_PROPERTY_SHOW(elements, ordered_list);
> > +static struct kobj_attribute  ordered_list_elements_val =3D
> > +     __ATTR_RO(elements);
> > +

<snip>

> > +
> > +
> > +int populate_ordered_list_elements_from_package(union acpi_object *ord=
er_obj,
> > +                                             int order_obj_count,
> > +                                             int instance_id)
> > +{
> > +     char *str_value =3D NULL;
> > +     int value_len;
> > +     int ret =3D 0;
> > +     u32 size =3D 0;
> > +     u32 int_value;
> > +     int elem =3D 0;
> > +     int reqs;
> > +     int eloc;
> > +     char *tmpstr =3D NULL;
> > +     char *part_tmp =3D NULL;
> > +     int tmp_len =3D 0;
> > +     char *part =3D NULL;
> > +
> > +     if (!order_obj)
> > +             return -EINVAL;
> > +
> > +     strscpy(bioscfg_drv.ordered_list_data[instance_id].common.display=
_name_language_code,
> > +             LANG_CODE_STR,
> > +             sizeof(bioscfg_drv.ordered_list_data[instance_id].common.=
display_name_language_code));
>
> This seems to be the same for every type. Can it not be moved into
> common code?

Each instance requires to report 'display_name_language_code' hence it
cannot be moved to a common code.
>

<snip>