x86/intel_rdt/mba_sc: Add schemata support

Currently when user updates the "schemata" with new MBA percentage
values, kernel writes the corresponding bandwidth percentage values to
the IA32_MBA_THRTL_MSR.

When MBA is expressed in MBps, the schemata format is changed to have the
per package memory bandwidth in MBps instead of being specified in
percentage. Do not write the IA32_MBA_THRTL_MSRs when the schemata is
updated as that is handled separately.

Signed-off-by: Vikas Shivappa <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

Author: Vikas Shivappa

arch/x86/kernel/cpu/intel_rdt.c

@@ -179,7 +179,7 @@ struct rdt_resource rdt_resources_all[] = {
 		.msr_update		= mba_wrmsr,
 		.cache_level		= 3,
 		.parse_ctrlval		= parse_bw,
-		.format_str		= "%d=%*d",
+		.format_str		= "%d=%*u",
 		.fflags			= RFTYPE_RES_MB,
 	},
 };

arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c

@@ -53,7 +53,8 @@ static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
 		return false;
 	}
 
-	if (bw < r->membw.min_bw || bw > r->default_ctrl) {
+	if ((bw < r->membw.min_bw || bw > r->default_ctrl) &&
+	    !is_mba_sc(r)) {
 		rdt_last_cmd_printf("MB value %ld out of range [%d,%d]\n", bw,
 				    r->membw.min_bw, r->default_ctrl);
 		return false;
@@ -179,6 +180,8 @@ static int update_domains(struct rdt_resource *r, int closid)
 	struct msr_param msr_param;
 	cpumask_var_t cpu_mask;
 	struct rdt_domain *d;
+	bool mba_sc;
+	u32 *dc;
 	int cpu;
 
 	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
@@ -188,13 +191,20 @@ static int update_domains(struct rdt_resource *r, int closid)
 	msr_param.high = msr_param.low + 1;
 	msr_param.res = r;
 
+	mba_sc = is_mba_sc(r);
 	list_for_each_entry(d, &r->domains, list) {
-		if (d->have_new_ctrl && d->new_ctrl != d->ctrl_val[closid]) {
+		dc = !mba_sc ? d->ctrl_val : d->mbps_val;
+		if (d->have_new_ctrl && d->new_ctrl != dc[closid]) {
 			cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
-			d->ctrl_val[closid] = d->new_ctrl;
+			dc[closid] = d->new_ctrl;
 		}
 	}
-	if (cpumask_empty(cpu_mask))
+
+	/*
+	 * Avoid writing the control msr with control values when
+	 * MBA software controller is enabled
+	 */
+	if (cpumask_empty(cpu_mask) || mba_sc)
 		goto done;
 	cpu = get_cpu();
 	/* Update CBM on this cpu if it's in cpu_mask. */
@@ -282,13 +292,17 @@ static void show_doms(struct seq_file *s, struct rdt_resource *r, int closid)
 {
 	struct rdt_domain *dom;
 	bool sep = false;
+	u32 ctrl_val;
 
 	seq_printf(s, "%*s:", max_name_width, r->name);
 	list_for_each_entry(dom, &r->domains, list) {
 		if (sep)
 			seq_puts(s, ";");
+
+		ctrl_val = (!is_mba_sc(r) ? dom->ctrl_val[closid] :
+			    dom->mbps_val[closid]);
 		seq_printf(s, r->format_str, dom->id, max_data_width,
-			   dom->ctrl_val[closid]);
+			   ctrl_val);
 		sep = true;
 	}
 	seq_puts(s, "\n");