x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data

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.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jamie Iles <quic_jiles@quicinc.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Xin Hao <xhao@linux.alibaba.com>
Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20220902154829.30399-21-james.morse@arm.com

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index e91afe99b7632f11c7689686354f896f3ee003c4..8d15568d7121c4d03fc93fc3027040ce5c89a475 100644 (file)
--- 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 849bdec37217e19b9714cf995e7743f853207578..e5a48f05e7876adcfb942e48f930603c2375fd19 100644 (file)
--- 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 9995d043650a94443906a572ce46e19696c7bdde..cb857f75332286fa69eca2f0747deed352e71d49 100644 (file)
--- 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 */