x86/intel_rdt/mba_sc: Add initialization support

When MBA software controller is enabled, a per domain storage is required
for user specified bandwidth in "MBps" and the "percentage" values which
are programmed into the IA32_MBA_THRTL_MSR. Add support for these data
structures and initialization.

The MBA percentage values have a default max value of 100 but however the
max value in MBps is not available from the hardware so it's set to
U32_MAX.

This simply says that the control group can use all bandwidth by default
but does not say what is the actual max bandwidth available. The actual
bandwidth that is available may depend on lot of factors like QPI link,
number of memory channels, memory channel frequency, its width and memory
speed, how many channels are configured and also if memory interleaving is
enabled. So there is no way to determine the maximum at runtime reliably.

Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/1524263781-14267-4-git-send-email-vikas.shivappa@linux.intel.com

1 files changed, 27 insertions, 10 deletions

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 53ee6838c496..8c09e9db2fc6 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -35,6 +35,7 @@
 
 #define MAX_MBA_BW	100u
 #define MBA_IS_LINEAR	0x4
+#define MBA_MAX_MBPS	U32_MAX
 
 /* Mutex to protect rdtgroup access. */
 DEFINE_MUTEX(rdtgroup_mutex);
@@ -439,25 +440,40 @@ struct rdt_domain *rdt_find_domain(struct rdt_resource *r, int id,
 	return NULL;
 }
 
+void setup_default_ctrlval(struct rdt_resource *r, u32 *dc, u32 *dm)
+{
+	int i;
+
+	/*
+	 * Initialize the Control MSRs to having no control.
+	 * For Cache Allocation: Set all bits in cbm
+	 * For Memory Allocation: Set b/w requested to 100%
+	 * and the bandwidth in MBps to U32_MAX
+	 */
+	for (i = 0; i < r->num_closid; i++, dc++, dm++) {
+		*dc = r->default_ctrl;
+		*dm = MBA_MAX_MBPS;
+	}
+}
+
 static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
 {
 	struct msr_param m;
-	u32 *dc;
-	int i;
+	u32 *dc, *dm;
 
 	dc = kmalloc_array(r->num_closid, sizeof(*d->ctrl_val), GFP_KERNEL);
 	if (!dc)
 		return -ENOMEM;
 
-	d->ctrl_val = dc;
+	dm = kmalloc_array(r->num_closid, sizeof(*d->mbps_val), GFP_KERNEL);
+	if (!dm) {
+		kfree(dc);
+		return -ENOMEM;
+	}
 
-	/*
-	 * Initialize the Control MSRs to having no control.
-	 * For Cache Allocation: Set all bits in cbm
-	 * For Memory Allocation: Set b/w requested to 100
-	 */
-	for (i = 0; i < r->num_closid; i++, dc++)
-		*dc = r->default_ctrl;
+	d->ctrl_val = dc;
+	d->mbps_val = dm;
+	setup_default_ctrlval(r, dc, dm);
 
 	m.low = 0;
 	m.high = r->num_closid;
@@ -596,6 +612,7 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 		}
 
 		kfree(d->ctrl_val);
+		kfree(d->mbps_val);
 		kfree(d->rmid_busy_llc);
 		kfree(d->mbm_total);
 		kfree(d->mbm_local);