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Message-Id: <CVHOXKY6MYEL.1CX828Z7QWIBI@suppilovahvero>
Date: Wed, 13 Sep 2023 12:43:35 +0300
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Haitao Huang" <haitao.huang@...ux.intel.com>,
<dave.hansen@...ux.intel.com>, <tj@...nel.org>,
<linux-kernel@...r.kernel.org>, <linux-sgx@...r.kernel.org>,
<x86@...nel.org>, <cgroups@...r.kernel.org>, <tglx@...utronix.de>,
<mingo@...hat.com>, <bp@...en8.de>, <hpa@...or.com>,
<sohil.mehta@...el.com>
Cc: <zhiquan1.li@...el.com>, <kristen@...ux.intel.com>,
<seanjc@...gle.com>, <zhanb@...rosoft.com>,
<anakrish@...rosoft.com>, <mikko.ylinen@...ux.intel.com>,
<yangjie@...rosoft.com>
Subject: Re: [PATCH v4 02/18] cgroup/misc: Add SGX EPC resource type and
export APIs for SGX driver
On Wed Sep 13, 2023 at 7:06 AM EEST, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen@...ux.intel.com>
>
> The SGX driver will need to get access to the root misc_cg object
> to do iterative walks and also determine if a charge will be
> towards the root cgroup or not.
What is "a charge" and why does SGX driver need to do iterative walks?
Neither is explained here.
> To manage the SGX EPC memory via the misc controller, the SGX
> driver will also need to be able to iterate over the misc cgroup
> hierarchy.
Ambiguous language: misc_cg vs "misc controller". Are the different
types of objects? If not, then stick to misc_cg everywhere.
> Move parent_misc() into misc_cgroup.h and make inline to make this
> function available to SGX, rename it to misc_cg_parent(), and update
> misc.c to use the new name.
net/rxrpc/misc.c?
The point being that plain "misc.c" is ambiguous.
> Add per resource type private data so that SGX can store additional
> per cgroup data with the misc_cg struct.
Yet another term "misc cg struct", and not just "misc_cg" like in the
first paragraph.
>
> Allow SGX EPC memory to be a valid resource type for the misc
> controller.
>
> Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
> ---
> V4:
> - Moved this to the second in the series.
> ---
> include/linux/misc_cgroup.h | 29 +++++++++++++++++++++++++++++
> kernel/cgroup/misc.c | 25 ++++++++++++-------------
> 2 files changed, 41 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
> index e1bcd176c2de..6f8330f435ba 100644
> --- a/include/linux/misc_cgroup.h
> +++ b/include/linux/misc_cgroup.h
> @@ -17,6 +17,10 @@ enum misc_res_type {
> MISC_CG_RES_SEV,
> /* AMD SEV-ES ASIDs resource */
> MISC_CG_RES_SEV_ES,
> +#endif
> +#ifdef CONFIG_CGROUP_SGX_EPC
> + /* SGX EPC memory resource */
> + MISC_CG_RES_SGX_EPC,
> #endif
> MISC_CG_RES_TYPES
> };
> @@ -37,6 +41,7 @@ struct misc_res {
> u64 max;
> atomic64_t usage;
> atomic64_t events;
> + void *priv;
>
> /* per resource callback ops */
> int (*misc_cg_alloc)(struct misc_cg *cg);
> @@ -59,6 +64,7 @@ struct misc_cg {
> struct misc_res res[MISC_CG_RES_TYPES];
> };
>
> +struct misc_cg *misc_cg_root(void);
> u64 misc_cg_res_total_usage(enum misc_res_type type);
> int misc_cg_set_capacity(enum misc_res_type type, u64 capacity);
> int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount);
> @@ -78,6 +84,20 @@ static inline struct misc_cg *css_misc(struct cgroup_subsys_state *css)
> return css ? container_of(css, struct misc_cg, css) : NULL;
> }
>
> +/**
> + * misc_cg_parent() - Get the parent of the passed misc cgroup.
> + * @cgroup: cgroup whose parent needs to be fetched.
> + *
> + * Context: Any context.
> + * Return:
> + * * struct misc_cg* - Parent of the @cgroup.
> + * * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
> + */
> +static inline struct misc_cg *misc_cg_parent(struct misc_cg *cgroup)
> +{
> + return cgroup ? css_misc(cgroup->css.parent) : NULL;
> +}
> +
> /*
> * get_current_misc_cg() - Find and get the misc cgroup of the current task.
> *
> @@ -102,6 +122,15 @@ static inline void put_misc_cg(struct misc_cg *cg)
> }
>
> #else /* !CONFIG_CGROUP_MISC */
> +static inline struct misc_cg *misc_cg_root(void)
> +{
> + return NULL;
> +}
> +
> +static inline struct misc_cg *misc_cg_parent(struct misc_cg *cg)
> +{
> + return NULL;
> +}
>
> static inline u64 misc_cg_res_total_usage(enum misc_res_type type)
> {
> diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c
> index e0092170d0dd..dbd881be773f 100644
> --- a/kernel/cgroup/misc.c
> +++ b/kernel/cgroup/misc.c
> @@ -24,6 +24,10 @@ static const char *const misc_res_name[] = {
> /* AMD SEV-ES ASIDs resource */
> "sev_es",
> #endif
> +#ifdef CONFIG_CGROUP_SGX_EPC
> + /* Intel SGX EPC memory bytes */
> + "sgx_epc",
> +#endif
> };
>
> /* Root misc cgroup */
> @@ -40,18 +44,13 @@ static struct misc_cg root_cg;
> static u64 misc_res_capacity[MISC_CG_RES_TYPES];
>
> /**
> - * parent_misc() - Get the parent of the passed misc cgroup.
> - * @cgroup: cgroup whose parent needs to be fetched.
> - *
> - * Context: Any context.
> - * Return:
> - * * struct misc_cg* - Parent of the @cgroup.
> - * * %NULL - If @cgroup is null or the passed cgroup does not have a parent.
> + * misc_cg_root() - Return the root misc cgroup.
> */
> -static struct misc_cg *parent_misc(struct misc_cg *cgroup)
> +struct misc_cg *misc_cg_root(void)
> {
> - return cgroup ? css_misc(cgroup->css.parent) : NULL;
> + return &root_cg;
> }
> +EXPORT_SYMBOL_GPL(misc_cg_root);
>
> /**
> * valid_type() - Check if @type is valid or not.
> @@ -150,7 +149,7 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
> if (!amount)
> return 0;
>
> - for (i = cg; i; i = parent_misc(i)) {
> + for (i = cg; i; i = misc_cg_parent(i)) {
> res = &i->res[type];
>
> new_usage = atomic64_add_return(amount, &res->usage);
> @@ -163,12 +162,12 @@ int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
> return 0;
>
> err_charge:
> - for (j = i; j; j = parent_misc(j)) {
> + for (j = i; j; j = misc_cg_parent(j)) {
> atomic64_inc(&j->res[type].events);
> cgroup_file_notify(&j->events_file);
> }
>
> - for (j = cg; j != i; j = parent_misc(j))
> + for (j = cg; j != i; j = misc_cg_parent(j))
> misc_cg_cancel_charge(type, j, amount);
> misc_cg_cancel_charge(type, i, amount);
> return ret;
> @@ -190,7 +189,7 @@ void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, u64 amount)
> if (!(amount && valid_type(type) && cg))
> return;
>
> - for (i = cg; i; i = parent_misc(i))
> + for (i = cg; i; i = misc_cg_parent(i))
> misc_cg_cancel_charge(type, i, amount);
> }
> EXPORT_SYMBOL_GPL(misc_cg_uncharge);
> --
> 2.25.1
BR, Jarkko
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