Re: [PATCH v1 02/31] x86/resctrl: Add a helper to avoid reaching into the arch code resource list

Moger, Babu
2024-04-15T20:28:24Z

Hi James/Dave,

On 3/21/24 11:50, James Morse wrote:
> Resctrl occasionally wants to know something about a specific resource,
> in these cases it reaches into the arch code's rdt_resources_all[]
> array.
>
> Once the filesystem parts of resctrl are moved to /fs/, this means it
> will need visibility of the architecture specific struct
> resctrl_hw_resource definition, and the array of all resources.
> All architectures would also need a r_resctrl member in this struct.
>
> Instead, abstract this via a helper to allow architectures to do
> different things here. Move the level enum to the resctrl header and
> add a helper to retrieve the struct rdt_resource by 'rid'.
>
> resctrl_arch_get_resource() should not return NULL for any value in
> the enum, it may instead return a dummy resource that is
> !alloc_enabled && !mon_enabled.

Nit.
You may want to drop the second half of the statement. We don't have a
dummy resource.

>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> arch/x86/kernel/cpu/resctrl/core.c | 10 +++++++++-
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 2 +-
> arch/x86/kernel/cpu/resctrl/internal.h | 10 ----------
> arch/x86/kernel/cpu/resctrl/monitor.c | 8 ++++----
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 15 +++++++--------
> include/linux/resctrl.h | 17 +++++++++++++++++
> 6 files changed, 38 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 83e40341583e..b773b3bdebe3 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -122,6 +122,14 @@ struct rdt_hw_resource rdt_resources_all[] = {
> },
> };
>
> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)
> +{
> + if (l >= RDT_NUM_RESOURCES)
> + return NULL;
> +
> + return &rdt_resources_all[l].r_resctrl;
> +}
> +
> /*
> * cache_alloc_hsw_probe() - Have to probe for Intel haswell server CPUs
> * as they do not have CPUID enumeration support for Cache allocation.
> @@ -169,7 +177,7 @@ static inline void cache_alloc_hsw_probe(void)
> bool is_mba_sc(struct rdt_resource *r)
> {
> if (!r)
> - return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.mba_sc;
> + r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>
> /*
> * The software controller support is only applicable to MBA resource.
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 7997b47743a2..788ac0395645 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -599,7 +599,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> domid = md.u.domid;
> evtid = md.u.evtid;
>
> - r = &rdt_resources_all[resid].r_resctrl;
> + r = resctrl_arch_get_resource(resid);
> d = rdt_find_domain(r, domid, NULL);
> if (IS_ERR_OR_NULL(d)) {
> ret = -ENOENT;
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index c99f26ebe7a6..65990def6c79 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -466,16 +466,6 @@ extern struct rdt_hw_resource rdt_resources_all[];
> extern struct rdtgroup rdtgroup_default;
> extern struct dentry *debugfs_resctrl;
>
> -enum resctrl_res_level {
> - RDT_RESOURCE_L3,
> - RDT_RESOURCE_L2,
> - RDT_RESOURCE_MBA,
> - RDT_RESOURCE_SMBA,
> -
> - /* Must be the last */
> - RDT_NUM_RESOURCES,
> -};
> -
> static inline struct rdt_resource *resctrl_inc(struct rdt_resource *res)
> {
> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(res);
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index c34a35ec0f03..06565153ceb2 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -321,7 +321,7 @@ static void limbo_release_entry(struct rmid_entry *entry)
> */
> void __check_limbo(struct rdt_domain *d, bool force_free)
> {
> - struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> u32 idx_limit = resctrl_arch_system_num_rmid_idx();
> struct rmid_entry *entry;
> u32 idx, cur_idx = 1;
> @@ -467,7 +467,7 @@ int alloc_rmid(u32 closid)
>
> static void add_rmid_to_limbo(struct rmid_entry *entry)
> {
> - struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> struct rdt_domain *d;
> u32 idx;
>
> @@ -669,7 +669,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
> if (!is_mbm_local_enabled())
> return;
>
> - r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> + r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>
> closid = rgrp->closid;
> rmid = rgrp->mon.rmid;
> @@ -839,7 +839,7 @@ void mbm_handle_overflow(struct work_struct *work)
> if (!resctrl_mounted || !resctrl_arch_mon_capable())
> goto out_unlock;
>
> - r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> d = container_of(work, struct rdt_domain, mbm_over.work);
>
> list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 1767c1affa60..45372b6a6215 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2253,7 +2253,7 @@ static void l2_qos_cfg_update(void *arg)
>
> static inline bool is_mba_linear(void)
> {
> - return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.delay_linear;
> + return resctrl_arch_get_resource(RDT_RESOURCE_MBA)->membw.delay_linear;
> }
>
> static int set_cache_qos_cfg(int level, bool enable)
> @@ -2341,7 +2341,7 @@ static void mba_sc_domain_destroy(struct rdt_resource *r,
> */
> static bool supports_mba_mbps(void)
> {
> - struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
>
> return (is_mbm_local_enabled() &&
> r->alloc_capable && is_mba_linear());
> @@ -2353,7 +2353,7 @@ static bool supports_mba_mbps(void)
> */
> static int set_mba_sc(bool mba_sc)
> {
> - struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> + struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
> u32 num_closid = resctrl_arch_get_num_closid(r);
> struct rdt_domain *d;
> int i;
> @@ -2625,10 +2625,10 @@ static void schemata_list_destroy(void)
>
> static int rdt_get_tree(struct fs_context *fc)
> {
> + struct rdt_resource *l3 = resctrl_arch_get_resource(RDT_RESOURCE_L3);

Its is probably best to keep the resource name as r here to be consistent
with other changes.

> struct rdt_fs_context *ctx = rdt_fc2context(fc);
> unsigned long flags = RFTYPE_CTRL_BASE;
> struct rdt_domain *dom;
> - struct rdt_resource *r;
> int ret;
>
> cpus_read_lock();
> @@ -2701,8 +2701,7 @@ static int rdt_get_tree(struct fs_context *fc)
> resctrl_mounted = true;
>
> if (is_mbm_enabled()) {
> - r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> - list_for_each_entry(dom, &r->domains, list)
> + list_for_each_entry(dom, &l3->domains, list)
> mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL,
> RESCTRL_PICK_ANY_CPU);
> }
> @@ -3878,7 +3877,7 @@ static int rdtgroup_show_options(struct seq_file *seq, struct kernfs_root *kf)
> if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
> seq_puts(seq, ",cdpl2");
>
> - if (is_mba_sc(&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl))
> + if (is_mba_sc(resctrl_arch_get_resource(RDT_RESOURCE_MBA)))
> seq_puts(seq, ",mba_MBps");
>
> if (resctrl_debug)
> @@ -4068,7 +4067,7 @@ static void clear_childcpus(struct rdtgroup *r, unsigned int cpu)
>
> void resctrl_offline_cpu(unsigned int cpu)
> {
> - struct rdt_resource *l3 = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + struct rdt_resource *l3 = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> struct rdtgroup *rdtgrp;
> struct rdt_domain *d;
>
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index a365f67131ec..168cc9510069 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -36,6 +36,16 @@ enum resctrl_conf_type {
> CDP_DATA,
> };
>
> +enum resctrl_res_level {
> + RDT_RESOURCE_L3,
> + RDT_RESOURCE_L2,
> + RDT_RESOURCE_MBA,
> + RDT_RESOURCE_SMBA,
> +
> + /* Must be the last */
> + RDT_NUM_RESOURCES,
> +};
> +
> #define CDP_NUM_TYPES (CDP_DATA + 1)
>
> /*
> @@ -190,6 +200,13 @@ struct rdt_resource {
> bool cdp_capable;
> };
>
> +/*
> + * Get the resource that exists at this level. If the level is not supported
> + * a dummy/not-capable resource can be returned. Levels >= RDT_NUM_RESOURCES
> + * will return NULL.
> + */
> +struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l);
> +
> /**
> * struct resctrl_schema - configuration abilities of a resource presented to
> * user-space

--
Thanks
Babu Moger