[PATCH v7 20/49] x86/resctrl: Change mon_event_config_{read,write}() to be arch helpers

James Morse
2025-02-28T20:01:12Z

mon_event_config_{read,write}() are called via IPI and access model
specific registers to do their work.

To support another architecture, this needs abstracting.

Rename mon_event_config_{read,write}() to have a "resctrl_arch_"
prefix, and move their struct mon_config_info parameter into
<linux/resctrl.h>. This allows another architecture to supply an
implementation of these.

As struct mon_config_info is now exposed globally, give it a 'resctrl_'
prefix. MPAM systems need access to the domain to do this work, add
the resource and domain to struct resctrl_mon_config_info.

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: 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: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
Changes since v5:
* Renamed info to config_info.
* Added description of which fields are read and written in the structure.
* Clarified comment about which CPU this is called on for both kinds of
reader.

Changes since v3:
* Added comments over the read/write helper to explain the type of the void
pointer.

Changes since v1:
* [Whitespace only] Re-tabbed struct resctrl_mon_config_info in
<linux/resctrl.h> to fit the prevailing style.

Non-functional change.

* [Commit message only] Reword to align with the actual naming of the
definitions and destination header file.
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 46 +++++++++++++-------------
include/linux/resctrl.h | 31 +++++++++++++++++
2 files changed, 54 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index eb32fbc3abea..e7d1d8b6983d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1580,11 +1580,6 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
return ret;
}

-struct mon_config_info {
- u32 evtid;
- u32 mon_config;
-};
-
#define INVALID_CONFIG_INDEX UINT_MAX

/**
@@ -1609,31 +1604,32 @@ static inline unsigned int mon_event_config_index_get(u32 evtid)
}
}

-static void mon_event_config_read(void *info)
+void resctrl_arch_mon_event_config_read(void *_config_info)
{
- struct mon_config_info *mon_info = info;
+ struct resctrl_mon_config_info *config_info = _config_info;
unsigned int index;
u64 msrval;

- index = mon_event_config_index_get(mon_info->evtid);
+ index = mon_event_config_index_get(config_info->evtid);
if (index == INVALID_CONFIG_INDEX) {
- pr_warn_once("Invalid event id %d\n", mon_info->evtid);
+ pr_warn_once("Invalid event id %d\n", config_info->evtid);
return;
}
rdmsrl(MSR_IA32_EVT_CFG_BASE + index, msrval);

/* Report only the valid event configuration bits */
- mon_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
+ config_info->mon_config = msrval & MAX_EVT_CONFIG_BITS;
}

-static void mondata_config_read(struct rdt_mon_domain *d, struct mon_config_info *mon_info)
+static void mondata_config_read(struct resctrl_mon_config_info *mon_info)
{
- smp_call_function_any(&d->hdr.cpu_mask, mon_event_config_read, mon_info, 1);
+ smp_call_function_any(&mon_info->d->hdr.cpu_mask,
+ resctrl_arch_mon_event_config_read, mon_info, 1);
}

static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid)
{
- struct mon_config_info mon_info;
+ struct resctrl_mon_config_info mon_info;
struct rdt_mon_domain *dom;
bool sep = false;

@@ -1644,9 +1640,11 @@ static int mbm_config_show(struct seq_file *s, struct rdt_resource *r, u32 evtid
if (sep)
seq_puts(s, ";");

- memset(&mon_info, 0, sizeof(struct mon_config_info));
+ memset(&mon_info, 0, sizeof(struct resctrl_mon_config_info));
+ mon_info.r = r;
+ mon_info.d = dom;
mon_info.evtid = evtid;
- mondata_config_read(dom, &mon_info);
+ mondata_config_read(&mon_info);

seq_printf(s, "%d=0x%02x", dom->hdr.id, mon_info.mon_config);
sep = true;
@@ -1679,30 +1677,32 @@ static int mbm_local_bytes_config_show(struct kernfs_open_file *of,
return 0;
}

-static void mon_event_config_write(void *info)
+void resctrl_arch_mon_event_config_write(void *_config_info)
{
- struct mon_config_info *mon_info = info;
+ struct resctrl_mon_config_info *config_info = _config_info;
unsigned int index;

- index = mon_event_config_index_get(mon_info->evtid);
+ index = mon_event_config_index_get(config_info->evtid);
if (index == INVALID_CONFIG_INDEX) {
- pr_warn_once("Invalid event id %d\n", mon_info->evtid);
+ pr_warn_once("Invalid event id %d\n", config_info->evtid);
return;
}
- wrmsr(MSR_IA32_EVT_CFG_BASE + index, mon_info->mon_config, 0);
+ wrmsr(MSR_IA32_EVT_CFG_BASE + index, config_info->mon_config, 0);
}

static void mbm_config_write_domain(struct rdt_resource *r,
struct rdt_mon_domain *d, u32 evtid, u32 val)
{
- struct mon_config_info mon_info = {0};
+ struct resctrl_mon_config_info mon_info = {0};

/*
* Read the current config value first. If both are the same then
* no need to write it again.
*/
+ mon_info.r = r;
+ mon_info.d = d;
mon_info.evtid = evtid;
- mondata_config_read(d, &mon_info);
+ mondata_config_read(&mon_info);
if (mon_info.mon_config == val)
return;

@@ -1714,7 +1714,7 @@ static void mbm_config_write_domain(struct rdt_resource *r,
* are scoped at the domain level. Writing any of these MSRs
* on one CPU is observed by all the CPUs in the domain.
*/
- smp_call_function_any(&d->hdr.cpu_mask, mon_event_config_write,
+ smp_call_function_any(&d->hdr.cpu_mask, resctrl_arch_mon_event_config_write,
&mon_info, 1);

/*
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index cc76f308e6f3..90b6563cf532 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -270,6 +270,13 @@ struct resctrl_cpu_defaults {
u32 rmid;
};

+struct resctrl_mon_config_info {
+ struct rdt_resource *r;
+ struct rdt_mon_domain *d;
+ u32 evtid;
+ u32 mon_config;
+};
+
/**
* resctrl_arch_sync_cpu_closid_rmid() - Refresh this CPU's CLOSID and RMID.
* Call via IPI.
@@ -311,6 +318,30 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);

__init bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);

+/**
+ * resctrl_arch_mon_event_config_write() - Write the config for an event.
+ * @config_info: struct resctrl_mon_config_info describing the resource, domain
+ * and event.
+ *
+ * Reads resource, domain and eventid from @config_info and writes the
+ * event config_info->mon_config into hardware.
+ *
+ * Called via IPI to reach a CPU that is a member of the specified domain.
+ */
+void resctrl_arch_mon_event_config_write(void *config_info);
+
+/**
+ * resctrl_arch_mon_event_config_read() - Read the config for an event.
+ * @config_info: struct resctrl_mon_config_info describing the resource, domain
+ * and event.
+ *
+ * Reads resource, domain and eventid from @config_info and reads the
+ * hardware config value into config_info->mon_config.
+ *
+ * Called via IPI to reach a CPU that is a member of the specified domain.
+ */
+void resctrl_arch_mon_event_config_read(void *config_info);
+
/*
* Update the ctrl_val and apply this config right now.
* Must be called on one of the domain's CPUs.
--
2.39.5