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Subject[PATCH v5 09/21] x86/resctrl: Switch over to the resctrl mbps_val list
Date
Updates to resctrl's software controller follow the same path as
other configuration updates, but they don't modify the hardware state.
rdtgroup_schemata_write() uses parse_line() and the resource's
parse_ctrlval() function to stage the configuration.
resctrl_arch_update_domains() then updates the mbps_val[] array
instead, and resctrl_arch_update_domains() skips the rdt_ctrl_update()
call that would update hardware.

This complicates the interface between resctrl's filesystem parts
and architecture specific code. It should be possible for mba_sc
to be completely implemented by the filesystem parts of resctrl. This
would allow it to work on a second architecture with no additional code.
resctrl_arch_update_domains() using the mbps_val[] array prevents this.

Change parse_bw() to write the configuration value directly to the
mbps_val[] array in the domain structure. Change rdtgroup_schemata_write()
to skip the call to resctrl_arch_update_domains(), meaning all the
mba_sc specific code in resctrl_arch_update_domains() can be removed.
On the read-side, show_doms() and update_mba_bw() are changed to read
the mbps_val[] array from the domain structure. With this,
resctrl_arch_get_config() no longer needs to consider mba_sc resources.

Reviewed-by: Jamie Iles <quic_jiles@quicinc.com>
Tested-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
Changes since v4:
* Wording of comments.
* Restored mbps_val[] reset code to set_mba_sc().
* Moved mbps_val[] reset in rdtgroup_init_mba() to reduce noise.

Changes since v3:
* Added the rdtgroup_init_mba() hunk to avoid ~0 being written
to the ctrl_val array, and to only reset mbps_val[] when its going
to be used.

Changes since v2:
* Fixed some names in the commit message.
* Added missing 'or mbps_val[]' code to rdtgroup_size_show()

Changes since v1:
* Squashed out struct resctrl_mba_sc
* Removed stray paragraphs from commit message
---
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 44 ++++++++++++++---------
arch/x86/kernel/cpu/resctrl/monitor.c | 10 +++---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 27 ++++++++++----
3 files changed, 52 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 87666275eed9..9f45207a6c74 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -61,6 +61,7 @@ int parse_bw(struct rdt_parse_data *data, struct resctrl_schema *s,
struct rdt_domain *d)
{
struct resctrl_staged_config *cfg;
+ u32 closid = data->rdtgrp->closid;
struct rdt_resource *r = s->res;
unsigned long bw_val;

@@ -72,6 +73,12 @@ int parse_bw(struct rdt_parse_data *data, struct resctrl_schema *s,

if (!bw_validate(data->buf, &bw_val, r))
return -EINVAL;
+
+ if (is_mba_sc(r)) {
+ d->mbps_val[closid] = bw_val;
+ return 0;
+ }
+
cfg->new_ctrl = bw_val;
cfg->have_new_ctrl = true;

@@ -261,14 +268,13 @@ static u32 get_config_index(u32 closid, enum resctrl_conf_type type)

static bool apply_config(struct rdt_hw_domain *hw_dom,
struct resctrl_staged_config *cfg, u32 idx,
- cpumask_var_t cpu_mask, bool mba_sc)
+ cpumask_var_t cpu_mask)
{
struct rdt_domain *dom = &hw_dom->d_resctrl;
- u32 *dc = !mba_sc ? hw_dom->ctrl_val : hw_dom->mbps_val;

- if (cfg->new_ctrl != dc[idx]) {
+ if (cfg->new_ctrl != hw_dom->ctrl_val[idx]) {
cpumask_set_cpu(cpumask_any(&dom->cpu_mask), cpu_mask);
- dc[idx] = cfg->new_ctrl;
+ hw_dom->ctrl_val[idx] = cfg->new_ctrl;

return true;
}
@@ -284,14 +290,12 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
enum resctrl_conf_type t;
cpumask_var_t cpu_mask;
struct rdt_domain *d;
- bool mba_sc;
int cpu;
u32 idx;

if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
return -ENOMEM;

- mba_sc = is_mba_sc(r);
msr_param.res = NULL;
list_for_each_entry(d, &r->domains, list) {
hw_dom = resctrl_to_arch_dom(d);
@@ -301,7 +305,7 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
continue;

idx = get_config_index(closid, t);
- if (!apply_config(hw_dom, cfg, idx, cpu_mask, mba_sc))
+ if (!apply_config(hw_dom, cfg, idx, cpu_mask))
continue;

if (!msr_param.res) {
@@ -315,11 +319,7 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
}
}

- /*
- * Avoid writing the control msr with control values when
- * MBA software controller is enabled
- */
- if (cpumask_empty(cpu_mask) || mba_sc)
+ if (cpumask_empty(cpu_mask))
goto done;
cpu = get_cpu();
/* Update resource control msr on this CPU if it's in cpu_mask. */
@@ -406,6 +406,14 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,

list_for_each_entry(s, &resctrl_schema_all, list) {
r = s->res;
+
+ /*
+ * Writes to mba_sc resources update the software controller,
+ * not the control msr.
+ */
+ if (is_mba_sc(r))
+ continue;
+
ret = resctrl_arch_update_domains(r, rdtgrp->closid);
if (ret)
goto out;
@@ -433,9 +441,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
u32 idx = get_config_index(closid, type);

- if (!is_mba_sc(r))
- return hw_dom->ctrl_val[idx];
- return hw_dom->mbps_val[idx];
+ return hw_dom->ctrl_val[idx];
}

static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
@@ -450,8 +456,12 @@ static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int clo
if (sep)
seq_puts(s, ";");

- ctrl_val = resctrl_arch_get_config(r, dom, closid,
- schema->conf_type);
+ if (is_mba_sc(r))
+ ctrl_val = dom->mbps_val[closid];
+ else
+ ctrl_val = resctrl_arch_get_config(r, dom, closid,
+ schema->conf_type);
+
seq_printf(s, r->format_str, dom->id, max_data_width,
ctrl_val);
sep = true;
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 497cadf3285d..16028b2f756a 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -447,13 +447,11 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
hw_dom_mba = resctrl_to_arch_dom(dom_mba);

cur_bw = pmbm_data->prev_bw;
- user_bw = resctrl_arch_get_config(r_mba, dom_mba, closid, CDP_NONE);
+ user_bw = dom_mba->mbps_val[closid];
delta_bw = pmbm_data->delta_bw;
- /*
- * resctrl_arch_get_config() chooses the mbps/ctrl value to return
- * based on is_mba_sc(). For now, reach into the hw_dom.
- */
- cur_msr_val = hw_dom_mba->ctrl_val[closid];
+
+ /* MBA resource doesn't support CDP */
+ cur_msr_val = resctrl_arch_get_config(r_mba, dom_mba, closid, CDP_NONE);

/*
* For Ctrl groups read data from child monitor groups.
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index bb1faf4f5b38..2b43bb9a9b76 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1356,11 +1356,13 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{
struct resctrl_schema *schema;
+ enum resctrl_conf_type type;
struct rdtgroup *rdtgrp;
struct rdt_resource *r;
struct rdt_domain *d;
unsigned int size;
int ret = 0;
+ u32 closid;
bool sep;
u32 ctrl;

@@ -1386,8 +1388,11 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
goto out;
}

+ closid = rdtgrp->closid;
+
list_for_each_entry(schema, &resctrl_schema_all, list) {
r = schema->res;
+ type = schema->conf_type;
sep = false;
seq_printf(s, "%*s:", max_name_width, schema->name);
list_for_each_entry(d, &r->domains, list) {
@@ -1396,9 +1401,12 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
size = 0;
} else {
- ctrl = resctrl_arch_get_config(r, d,
- rdtgrp->closid,
- schema->conf_type);
+ if (is_mba_sc(r))
+ ctrl = d->mbps_val[closid];
+ else
+ ctrl = resctrl_arch_get_config(r, d,
+ closid,
+ type);
if (r->rid == RDT_RESOURCE_MBA)
size = ctrl;
else
@@ -2818,14 +2826,19 @@ static int rdtgroup_init_cat(struct resctrl_schema *s, u32 closid)
}

/* Initialize MBA resource with default values. */
-static void rdtgroup_init_mba(struct rdt_resource *r)
+static void rdtgroup_init_mba(struct rdt_resource *r, u32 closid)
{
struct resctrl_staged_config *cfg;
struct rdt_domain *d;

list_for_each_entry(d, &r->domains, list) {
+ if (is_mba_sc(r)) {
+ d->mbps_val[closid] = MBA_MAX_MBPS;
+ continue;
+ }
+
cfg = &d->staged_config[CDP_NONE];
- cfg->new_ctrl = is_mba_sc(r) ? MBA_MAX_MBPS : r->default_ctrl;
+ cfg->new_ctrl = r->default_ctrl;
cfg->have_new_ctrl = true;
}
}
@@ -2840,7 +2853,9 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
list_for_each_entry(s, &resctrl_schema_all, list) {
r = s->res;
if (r->rid == RDT_RESOURCE_MBA) {
- rdtgroup_init_mba(r);
+ rdtgroup_init_mba(r, rdtgrp->closid);
+ if (is_mba_sc(r))
+ continue;
} else {
ret = rdtgroup_init_cat(s, rdtgrp->closid);
if (ret < 0)
--
2.30.2
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