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Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Date: Tue, 30 Apr 2024 22:18:43 -0700
Message-ID: <CAC41dw-g2=jKkevGOJUqnzYTpxQ8+Z_JxnNNuoLR+CM_yqfRzA@mail.gmail.com>
Subject: Re: [PATCH v4 13/15] x86/sev: Take advantage of configfs visibility
 support in TSM
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-coco@lists.linux.dev, 
	svsm-devel@coconut-svsm.dev, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Dave Hansen <dave.hansen@linux.intel.com>, "H. Peter Anvin" <hpa@zytor.com>, 
	Andy Lutomirski <luto@kernel.org>, Peter Zijlstra <peterz@infradead.org>, 
	Dan Williams <dan.j.williams@intel.com>, Michael Roth <michael.roth@amd.com>, 
	Ashish Kalra <ashish.kalra@amd.com>
Content-Type: text/plain; charset="UTF-8"
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On Wed, Apr 24, 2024 at 9:00=E2=80=AFAM Tom Lendacky <thomas.lendacky@amd.c=
om> wrote:
>
> The TSM attestation report support provides multiple configfs attribute
> types (both for standard and binary attributes) to allow for additional
> attributes to be displayed for SNP as compared to TDX. With the ability
> to hide attributes via configfs, consoldate the multiple attribute groups
> into a single standard attribute group and a single binary attribute
> group. Modify the TDX support to hide the attributes that were previously
> "hidden" as a result of registering the selective attribute groups.
>
> Co-developed-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  drivers/virt/coco/sev-guest/sev-guest.c |  3 +-
>  drivers/virt/coco/tdx-guest/tdx-guest.c | 29 ++++++++-
>  drivers/virt/coco/tsm.c                 | 82 ++++++++++++-------------
>  include/linux/tsm.h                     | 41 ++++++++++---
>  4 files changed, 102 insertions(+), 53 deletions(-)
>
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/=
sev-guest/sev-guest.c
> index 2abb51bd034f..ec3d894cfe31 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -23,6 +23,7 @@
>  #include <linux/sockptr.h>
>  #include <linux/cleanup.h>
>  #include <linux/uuid.h>
> +#include <linux/configfs.h>
>  #include <uapi/linux/sev-guest.h>
>  #include <uapi/linux/psp-sev.h>
>
> @@ -975,7 +976,7 @@ static int __init sev_guest_probe(struct platform_dev=
ice *pdev)
>         /* Set the privlevel_floor attribute based on the vmpck_id */
>         sev_tsm_ops.privlevel_floor =3D vmpck_id;
>
> -       ret =3D tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_typ=
e);
> +       ret =3D tsm_register(&sev_tsm_ops, snp_dev);
>         if (ret)
>                 goto e_free_cert_data;
>
> diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/=
tdx-guest/tdx-guest.c
> index 1253bf76b570..964af57f345c 100644
> --- a/drivers/virt/coco/tdx-guest/tdx-guest.c
> +++ b/drivers/virt/coco/tdx-guest/tdx-guest.c
> @@ -17,6 +17,7 @@
>  #include <linux/delay.h>
>  #include <linux/tsm.h>
>  #include <linux/sizes.h>
> +#include <linux/configfs.h>
>
>  #include <uapi/linux/tdx-guest.h>
>
> @@ -249,6 +250,30 @@ static int tdx_report_new(struct tsm_report *report,=
 void *data)
>         return ret;
>  }
>
> +static bool tdx_report_attr_visible(struct config_item *item,
> +                                   struct configfs_attribute *attr, int =
n)
> +{
> +       switch (n) {
> +       case TSM_REPORT_GENERATION:
> +       case TSM_REPORT_PROVIDER:
> +               return true;
> +       }
> +
> +       return false;
> +}
> +
> +static bool tdx_report_bin_attr_visible(struct config_item *item,
> +                                       struct configfs_bin_attribute *at=
tr, int n)
> +{
> +       switch (n) {
> +       case TSM_REPORT_INBLOB:
> +       case TSM_REPORT_OUTBLOB:
> +               return true;
> +       }
> +
> +       return false;
> +}
> +
>  static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
>                             unsigned long arg)
>  {
> @@ -281,6 +306,8 @@ MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);
>  static const struct tsm_ops tdx_tsm_ops =3D {
>         .name =3D KBUILD_MODNAME,
>         .report_new =3D tdx_report_new,
> +       .report_attr_visible =3D tdx_report_attr_visible,
> +       .report_bin_attr_visible =3D tdx_report_bin_attr_visible,
>  };
>
>  static int __init tdx_guest_init(void)
> @@ -301,7 +328,7 @@ static int __init tdx_guest_init(void)
>                 goto free_misc;
>         }
>
> -       ret =3D tsm_register(&tdx_tsm_ops, NULL, NULL);
> +       ret =3D tsm_register(&tdx_tsm_ops, NULL);
>         if (ret)
>                 goto free_quote;
>
> diff --git a/drivers/virt/coco/tsm.c b/drivers/virt/coco/tsm.c
> index d1c2db83a8ca..dedb4f582630 100644
> --- a/drivers/virt/coco/tsm.c
> +++ b/drivers/virt/coco/tsm.c
> @@ -14,7 +14,6 @@
>
>  static struct tsm_provider {
>         const struct tsm_ops *ops;
> -       const struct config_item_type *type;
>         void *data;
>  } provider;
>  static DECLARE_RWSEM(tsm_rwsem);
> @@ -252,34 +251,18 @@ static ssize_t tsm_report_auxblob_read(struct confi=
g_item *cfg, void *buf,
>  }
>  CONFIGFS_BIN_ATTR_RO(tsm_report_, auxblob, NULL, TSM_OUTBLOB_MAX);
>
> -#define TSM_DEFAULT_ATTRS() \
> -       &tsm_report_attr_generation, \
> -       &tsm_report_attr_provider
> -
>  static struct configfs_attribute *tsm_report_attrs[] =3D {
> -       TSM_DEFAULT_ATTRS(),
> +       [TSM_REPORT_GENERATION] =3D &tsm_report_attr_generation,
> +       [TSM_REPORT_PROVIDER] =3D &tsm_report_attr_provider,
> +       [TSM_REPORT_PRIVLEVEL] =3D &tsm_report_attr_privlevel,
> +       [TSM_REPORT_PRIVLEVEL_FLOOR] =3D &tsm_report_attr_privlevel_floor=
,
>         NULL,
>  };
>
> -static struct configfs_attribute *tsm_report_extra_attrs[] =3D {
> -       TSM_DEFAULT_ATTRS(),
> -       &tsm_report_attr_privlevel,
> -       &tsm_report_attr_privlevel_floor,
> -       NULL,
> -};
> -
> -#define TSM_DEFAULT_BIN_ATTRS() \
> -       &tsm_report_attr_inblob, \
> -       &tsm_report_attr_outblob
> -
>  static struct configfs_bin_attribute *tsm_report_bin_attrs[] =3D {
> -       TSM_DEFAULT_BIN_ATTRS(),
> -       NULL,
> -};
> -
> -static struct configfs_bin_attribute *tsm_report_bin_extra_attrs[] =3D {
> -       TSM_DEFAULT_BIN_ATTRS(),
> -       &tsm_report_attr_auxblob,
> +       [TSM_REPORT_INBLOB] =3D &tsm_report_attr_inblob,
> +       [TSM_REPORT_OUTBLOB] =3D &tsm_report_attr_outblob,
> +       [TSM_REPORT_AUXBLOB] =3D &tsm_report_attr_auxblob,
>         NULL,
>  };
>
> @@ -297,21 +280,12 @@ static struct configfs_item_operations tsm_report_i=
tem_ops =3D {
>         .release =3D tsm_report_item_release,
>  };
>
> -const struct config_item_type tsm_report_default_type =3D {
> +static const struct config_item_type tsm_report_type =3D {
>         .ct_owner =3D THIS_MODULE,
>         .ct_bin_attrs =3D tsm_report_bin_attrs,
>         .ct_attrs =3D tsm_report_attrs,
>         .ct_item_ops =3D &tsm_report_item_ops,
>  };
> -EXPORT_SYMBOL_GPL(tsm_report_default_type);
> -
> -const struct config_item_type tsm_report_extra_type =3D {
> -       .ct_owner =3D THIS_MODULE,
> -       .ct_bin_attrs =3D tsm_report_bin_extra_attrs,
> -       .ct_attrs =3D tsm_report_extra_attrs,
> -       .ct_item_ops =3D &tsm_report_item_ops,
> -};
> -EXPORT_SYMBOL_GPL(tsm_report_extra_type);
>
>  static struct config_item *tsm_report_make_item(struct config_group *gro=
up,
>                                                 const char *name)
> @@ -326,12 +300,40 @@ static struct config_item *tsm_report_make_item(str=
uct config_group *group,
>         if (!state)
>                 return ERR_PTR(-ENOMEM);
>
> -       config_item_init_type_name(&state->cfg, name, provider.type);
> +       config_item_init_type_name(&state->cfg, name, &tsm_report_type);
>         return &state->cfg;
>  }
>
> +static bool tsm_report_is_visible(struct config_item *item,
> +                                 struct configfs_attribute *attr, int n)
> +{
> +       guard(rwsem_read)(&tsm_rwsem);
> +       if (!provider.ops)
> +               return false;
> +
> +       if (!provider.ops->report_attr_visible)
> +               return true;
> +
> +       return provider.ops->report_attr_visible(item, attr, n);
> +}
> +
> +static bool tsm_report_is_bin_visible(struct config_item *item,
> +                                     struct configfs_bin_attribute *attr=
, int n)
> +{
> +       guard(rwsem_read)(&tsm_rwsem);
> +       if (!provider.ops)
> +               return false;
> +
> +       if (!provider.ops->report_bin_attr_visible)
> +               return true;
> +
> +       return provider.ops->report_bin_attr_visible(item, attr, n);
> +}
> +
>  static struct configfs_group_operations tsm_report_group_ops =3D {
>         .make_item =3D tsm_report_make_item,
> +       .is_visible =3D tsm_report_is_visible,
> +       .is_bin_visible =3D tsm_report_is_bin_visible,
>  };
>
>  static const struct config_item_type tsm_reports_type =3D {
> @@ -353,16 +355,10 @@ static struct configfs_subsystem tsm_configfs =3D {
>         .su_mutex =3D __MUTEX_INITIALIZER(tsm_configfs.su_mutex),
>  };
>
> -int tsm_register(const struct tsm_ops *ops, void *priv,
> -                const struct config_item_type *type)
> +int tsm_register(const struct tsm_ops *ops, void *priv)
>  {
>         const struct tsm_ops *conflict;
>
> -       if (!type)
> -               type =3D &tsm_report_default_type;
> -       if (!(type =3D=3D &tsm_report_default_type || type =3D=3D &tsm_re=
port_extra_type))
> -               return -EINVAL;
> -
>         guard(rwsem_write)(&tsm_rwsem);
>         conflict =3D provider.ops;
>         if (conflict) {
> @@ -372,7 +368,6 @@ int tsm_register(const struct tsm_ops *ops, void *pri=
v,
>
>         provider.ops =3D ops;
>         provider.data =3D priv;
> -       provider.type =3D type;
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(tsm_register);
> @@ -384,7 +379,6 @@ int tsm_unregister(const struct tsm_ops *ops)
>                 return -EBUSY;
>         provider.ops =3D NULL;
>         provider.data =3D NULL;
> -       provider.type =3D NULL;
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(tsm_unregister);
> diff --git a/include/linux/tsm.h b/include/linux/tsm.h
> index 50c5769657d8..fa19291a9854 100644
> --- a/include/linux/tsm.h
> +++ b/include/linux/tsm.h
> @@ -4,6 +4,7 @@
>
>  #include <linux/sizes.h>
>  #include <linux/types.h>
> +#include <linux/configfs.h>
>
>  #define TSM_INBLOB_MAX 64
>  #define TSM_OUTBLOB_MAX SZ_32K
> @@ -42,12 +43,40 @@ struct tsm_report {
>         u8 *auxblob;
>  };
>
> +/**
> + * enum tsm_attr_index - index used to reference report attributes
> + * @TSM_REPORT_GENERATION: index of the report generation number attribu=
te
> + * @TSM_REPORT_PROVIDER: index of the provider name attribute
> + * @TSM_REPORT_PRIVLEVEL: index of the desired privilege level attribute
> + * @TSM_REPORT_PRIVLEVEL_FLOOR: index of the minimum allowed privileg le=
vel attribute

/s/privleg/privlege

> + */
> +enum tsm_attr_index {
> +       TSM_REPORT_GENERATION,

Do we need an index for the generation attribute ? Since it is a core
function, we can allow it by default.

> +       TSM_REPORT_PROVIDER,

Same as above.

> +       TSM_REPORT_PRIVLEVEL,
> +       TSM_REPORT_PRIVLEVEL_FLOOR,
> +};
> +
> +/**
> + * enum tsm_bin_attr_index - index used to reference binary report attri=
butes
> + * @TSM_REPORT_INBLOB: index of the binary report input attribute
> + * @TSM_REPORT_OUTBLOB: index of the binary report output attribute
> + * @TSM_REPORT_AUXBLOB: index of the binary auxiliary data attribute
> + */
> +enum tsm_bin_attr_index {
> +       TSM_REPORT_INBLOB,
> +       TSM_REPORT_OUTBLOB,
> +       TSM_REPORT_AUXBLOB,
> +};

Why differentiate between bin attr and regular attr? Why not use the same e=
num?

> +
>  /**
>   * struct tsm_ops - attributes and operations for tsm instances
>   * @name: tsm id reflected in /sys/kernel/config/tsm/report/$report/prov=
ider
>   * @privlevel_floor: convey base privlevel for nested scenarios
>   * @report_new: Populate @report with the report blob and auxblob
>   * (optional), return 0 on successful population, or -errno otherwise
> + * @report_attr_visible: show or hide a report attribute entry
> + * @report_bin_attr_visible: show or hide a report binary attribute entr=
y
>   *
>   * Implementation specific ops, only one is expected to be registered at
>   * a time i.e. only one of "sev-guest", "tdx-guest", etc.
> @@ -56,14 +85,12 @@ struct tsm_ops {
>         const char *name;
>         unsigned int privlevel_floor;
>         int (*report_new)(struct tsm_report *report, void *data);
> +       bool (*report_attr_visible)(struct config_item *item,
> +                                   struct configfs_attribute *attr, int =
n);
> +       bool (*report_bin_attr_visible)(struct config_item *item,
> +                                       struct configfs_bin_attribute *at=
tr, int n);

I think we can use a single callback . We don't really gain anything
with bin attr differentiation.

>  };
>
> -extern const struct config_item_type tsm_report_default_type;
> -
> -/* publish @privlevel, @privlevel_floor, and @auxblob attributes */
> -extern const struct config_item_type tsm_report_extra_type;
> -
> -int tsm_register(const struct tsm_ops *ops, void *priv,
> -                const struct config_item_type *type);
> +int tsm_register(const struct tsm_ops *ops, void *priv);
>  int tsm_unregister(const struct tsm_ops *ops);
>  #endif /* __TSM_H */
> --
> 2.43.2
>