arm64/mpam: implenment mpam_sched_in()

hulk inclusion
category: feature
bugzilla: 5510
CVE: NA

split from xiaojun's big patch.
Signed-off-by: NTan Xiaojun <tanxiaojun@huawei.com>
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/mpam_sched.h

 #ifndef _ASM_ARM64_MPAM_SCHED_H
 #define _ASM_ARM64_MPAM_SCHED_H
 
+#ifdef CONFIG_MPAM
+
 #include <linux/sched.h>
 #include <linux/jump_label.h>
 
+#include <asm/mpam.h>
+
 /**
  * struct intel_pqr_state - State cache for the PQR MSR
  * @cur_rmid:		The cached Resource Monitoring ID
@@ -28,6 +32,62 @@ struct intel_pqr_state {
 
 DECLARE_PER_CPU(struct intel_pqr_state, pqr_state);
 
+/*
+ * __intel_rdt_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR
+ *
+ * Following considerations are made so that this has minimal impact
+ * on scheduler hot path:
+ * - This will stay as no-op unless we are running on an Intel SKU
+ *   which supports resource control or monitoring and we enable by
+ *   mounting the resctrl file system.
+ * - Caches the per cpu CLOSid/RMID values and does the MSR write only
+ *   when a task with a different CLOSid/RMID is scheduled in.
+ * - We allocate RMIDs/CLOSids globally in order to keep this as
+ *   simple as possible.
+ * Must be called with preemption disabled.
+ */
+static void __mpam_sched_in(void)
+{
+	struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
+	u32 partid = state->default_closid;
+	u32 pmg = state->default_rmid;
+
+	/*
+	 * If this task has a closid/rmid assigned, use it.
+	 * Else use the closid/rmid assigned to this cpu.
+	 */
+	if (static_branch_likely(&resctrl_alloc_enable_key)) {
+		if (current->closid)
+			partid = current->closid;
+	}
+
+	if (static_branch_likely(&resctrl_mon_enable_key)) {
+		if (current->rmid)
+			pmg = current->rmid;
+	}
+
+	if (partid != state->cur_closid || pmg != state->cur_rmid) {
+		u64 reg;
+		state->cur_closid = partid;
+		state->cur_rmid = pmg;
+
+		reg = read_sysreg_s(SYS_MPAM0_EL1);
+		reg = reg & (~PARTID_MASK) & partid;
+		reg = reg & (~PMG_MASK) & pmg;
+		write_sysreg_s(reg, SYS_MPAM0_EL1);
+	}
+}
+
+static inline void mpam_sched_in(void)
+{
+	if (static_branch_likely(&resctrl_enable_key))
+		__mpam_sched_in();
+}
+
+#else
+
 static inline void mpam_sched_in(void) {}
 
+#endif /* CONFIG_MPAM */
+
 #endif