[PATCH v6 20/21] x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data

James Morse
2022-09-02T15:58:15Z

resctrl_rmid_realloc_threshold can be set by user-space. The maximum
value is specified by the architecture.

Currently max_threshold_occ_write() reads the maximum value from
boot_cpu_data.x86_cache_size, which is not portable to another
architecture.

Add resctrl_rmid_realloc_limit to describe the maximum size in bytes
that user-space can set the threshold to.

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>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
arch/x86/kernel/cpu/resctrl/monitor.c | 9 +++++++--
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
include/linux/resctrl.h | 1 +
3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index e91afe99b763..8d15568d7121 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -67,6 +67,11 @@ unsigned int rdt_mon_features;
*/
unsigned int resctrl_rmid_realloc_threshold;

+/*
+ * This is the maximum value for the reallocation threshold, in bytes.
+ */
+unsigned int resctrl_rmid_realloc_limit;
+
#define CF(cf) ((unsigned long)(1048576 * (cf) + 0.5))

/*
@@ -747,10 +752,10 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
{
unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
- unsigned int cl_size = boot_cpu_data.x86_cache_size;
unsigned int threshold;
int ret;

+ resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024;
hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale;
r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1;
hw_res->mbm_width = MBM_CNTR_WIDTH_BASE;
@@ -767,7 +772,7 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
*
* For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC.
*/
- threshold = cl_size * 1024 / r->num_rmid;
+ threshold = resctrl_rmid_realloc_limit / r->num_rmid;

/*
* Because num_rmid may not be a power of two, round the value
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 849bdec37217..e5a48f05e787 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1059,7 +1059,7 @@ static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
if (ret)
return ret;

- if (bytes > (boot_cpu_data.x86_cache_size * 1024))
+ if (bytes > resctrl_rmid_realloc_limit)
return -EINVAL;

resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(bytes);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 9995d043650a..cb857f753322 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -251,5 +251,6 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d,
u32 rmid, enum resctrl_event_id eventid);

extern unsigned int resctrl_rmid_realloc_threshold;
+extern unsigned int resctrl_rmid_realloc_limit;

#endif /* _RESCTRL_H */
--
2.30.2