[PATCH v7 02/49] x86/resctrl: Add a helper to avoid reaching into the arch code resource list

James Morse
2025-02-28T20:00:06Z

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
rdt_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.

Co-developed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Change since v5:
* Ensure rdt_resources_all[] is always padded to RDT_NUM_RESOURCES

Changes since v1:
* Backed out non-functional renaming of "r" to "l3" in rdt_get_tree(),
and unhoisted the assignment of r (as now is) back into the if ()
where it started out. There seem to be no uses of this variable
outside this if().
* [Commit message only] Typo fix:
s/resctrl_hw_resource/rdt_hw_resource/g
---
arch/x86/kernel/cpu/resctrl/core.c | 12 ++++++++++--
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 | 14 +++++++-------
include/linux/resctrl.h | 17 +++++++++++++++++
6 files changed, 39 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 3d1735ed8d1f..12b41316d8f7 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -62,7 +62,7 @@ static void mba_wrmsr_amd(struct msr_param *m);
#define ctrl_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.ctrl_domains)
#define mon_domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.mon_domains)

-struct rdt_hw_resource rdt_resources_all[] = {
+struct rdt_hw_resource rdt_resources_all[RDT_NUM_RESOURCES] = {
[RDT_RESOURCE_L3] =
{
.r_resctrl = {
@@ -127,6 +127,14 @@ u32 resctrl_arch_system_num_rmid_idx(void)
return r->num_rmid;
}

+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.
@@ -174,7 +182,7 @@ 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 536351159cc2..4af27ef5a8a1 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -649,7 +649,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
resid = md.u.rid;
domid = md.u.domid;
evtid = md.u.evtid;
- r = &rdt_resources_all[resid].r_resctrl;
+ r = resctrl_arch_get_resource(resid);

if (md.u.sum) {
/*
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 20c898f09b7e..75252a7e1ebc 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -512,16 +512,6 @@ extern struct rdtgroup rdtgroup_default;
extern struct dentry *debugfs_resctrl;
extern enum resctrl_event_id mba_mbps_default_event;

-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 94a1d9780461..58b5b21349a8 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -365,7 +365,7 @@ static void limbo_release_entry(struct rmid_entry *entry)
*/
void __check_limbo(struct rdt_mon_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;
@@ -521,7 +521,7 @@ 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_mon_domain *d;
u32 idx;

@@ -761,7 +761,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
struct rdtgroup *entry;
u32 cur_bw, user_bw;

- r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
+ r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
evt_id = rgrp->mba_mbps_event;

closid = rgrp->closid;
@@ -925,7 +925,7 @@ 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_mon_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 04b653d613e8..45093b9e8e63 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2256,7 +2256,7 @@ 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)
@@ -2346,8 +2346,8 @@ static void mba_sc_domain_destroy(struct rdt_resource *r,
*/
static bool supports_mba_mbps(void)
{
- struct rdt_resource *rmbm = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
- struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
+ struct rdt_resource *rmbm = resctrl_arch_get_resource(RDT_RESOURCE_L3);
+ struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);

return (is_mbm_enabled() &&
r->alloc_capable && is_mba_linear() &&
@@ -2360,7 +2360,7 @@ 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_ctrl_domain *d;
unsigned long fflags;
@@ -2714,7 +2714,7 @@ 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;
+ r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
list_for_each_entry(dom, &r->mon_domains, hdr.list)
mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL,
RESCTRL_PICK_ANY_CPU);
@@ -3951,7 +3951,7 @@ 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)
@@ -4151,7 +4151,7 @@ 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 rdt_mon_domain *d;
struct rdtgroup *rdtgrp;

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index d94abba1c716..37279e2a89da 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -37,6 +37,16 @@ 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)

/*
@@ -226,6 +236,13 @@ 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
--
2.39.5