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Message-ID: <CAC41dw-g2=jKkevGOJUqnzYTpxQ8+Z_JxnNNuoLR+CM_yqfRzA@mail.gmail.com>
Date: Tue, 30 Apr 2024 22:18:43 -0700
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, linux-coco@...ts.linux.dev,
svsm-devel@...onut-svsm.dev, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
Dan Williams <dan.j.williams@...el.com>, Michael Roth <michael.roth@....com>,
Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v4 13/15] x86/sev: Take advantage of configfs visibility
support in TSM
On Wed, Apr 24, 2024 at 9:00 AM Tom Lendacky <thomas.lendacky@....com> 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@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....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_device *pdev)
> /* Set the privlevel_floor attribute based on the vmpck_id */
> sev_tsm_ops.privlevel_floor = vmpck_id;
>
> - ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type);
> + ret = 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 *attr, 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 = {
> .name = KBUILD_MODNAME,
> .report_new = tdx_report_new,
> + .report_attr_visible = tdx_report_attr_visible,
> + .report_bin_attr_visible = 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 = tsm_register(&tdx_tsm_ops, NULL, NULL);
> + ret = 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 config_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[] = {
> - TSM_DEFAULT_ATTRS(),
> + [TSM_REPORT_GENERATION] = &tsm_report_attr_generation,
> + [TSM_REPORT_PROVIDER] = &tsm_report_attr_provider,
> + [TSM_REPORT_PRIVLEVEL] = &tsm_report_attr_privlevel,
> + [TSM_REPORT_PRIVLEVEL_FLOOR] = &tsm_report_attr_privlevel_floor,
> NULL,
> };
>
> -static struct configfs_attribute *tsm_report_extra_attrs[] = {
> - 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[] = {
> - TSM_DEFAULT_BIN_ATTRS(),
> - NULL,
> -};
> -
> -static struct configfs_bin_attribute *tsm_report_bin_extra_attrs[] = {
> - TSM_DEFAULT_BIN_ATTRS(),
> - &tsm_report_attr_auxblob,
> + [TSM_REPORT_INBLOB] = &tsm_report_attr_inblob,
> + [TSM_REPORT_OUTBLOB] = &tsm_report_attr_outblob,
> + [TSM_REPORT_AUXBLOB] = &tsm_report_attr_auxblob,
> NULL,
> };
>
> @@ -297,21 +280,12 @@ static struct configfs_item_operations tsm_report_item_ops = {
> .release = tsm_report_item_release,
> };
>
> -const struct config_item_type tsm_report_default_type = {
> +static const struct config_item_type tsm_report_type = {
> .ct_owner = THIS_MODULE,
> .ct_bin_attrs = tsm_report_bin_attrs,
> .ct_attrs = tsm_report_attrs,
> .ct_item_ops = &tsm_report_item_ops,
> };
> -EXPORT_SYMBOL_GPL(tsm_report_default_type);
> -
> -const struct config_item_type tsm_report_extra_type = {
> - .ct_owner = THIS_MODULE,
> - .ct_bin_attrs = tsm_report_bin_extra_attrs,
> - .ct_attrs = tsm_report_extra_attrs,
> - .ct_item_ops = &tsm_report_item_ops,
> -};
> -EXPORT_SYMBOL_GPL(tsm_report_extra_type);
>
> static struct config_item *tsm_report_make_item(struct config_group *group,
> const char *name)
> @@ -326,12 +300,40 @@ static struct config_item *tsm_report_make_item(struct 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 = {
> .make_item = tsm_report_make_item,
> + .is_visible = tsm_report_is_visible,
> + .is_bin_visible = tsm_report_is_bin_visible,
> };
>
> static const struct config_item_type tsm_reports_type = {
> @@ -353,16 +355,10 @@ static struct configfs_subsystem tsm_configfs = {
> .su_mutex = __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 = &tsm_report_default_type;
> - if (!(type == &tsm_report_default_type || type == &tsm_report_extra_type))
> - return -EINVAL;
> -
> guard(rwsem_write)(&tsm_rwsem);
> conflict = provider.ops;
> if (conflict) {
> @@ -372,7 +368,6 @@ int tsm_register(const struct tsm_ops *ops, void *priv,
>
> provider.ops = ops;
> provider.data = priv;
> - provider.type = type;
> return 0;
> }
> EXPORT_SYMBOL_GPL(tsm_register);
> @@ -384,7 +379,6 @@ int tsm_unregister(const struct tsm_ops *ops)
> return -EBUSY;
> provider.ops = NULL;
> provider.data = NULL;
> - provider.type = 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 attribute
> + * @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 level 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 attributes
> + * @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 enum?
> +
> /**
> * struct tsm_ops - attributes and operations for tsm instances
> * @name: tsm id reflected in /sys/kernel/config/tsm/report/$report/provider
> * @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 entry
> *
> * 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 *attr, 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
>
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