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-rw-r--r--arch/x86/include/asm/resctrl.h96
1 files changed, 96 insertions, 0 deletions
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
new file mode 100644
index 000000000000..07603064df8f
--- /dev/null
+++ b/arch/x86/include/asm/resctrl.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_RESCTRL_H
+#define _ASM_X86_RESCTRL_H
+
+#ifdef CONFIG_X86_CPU_RESCTRL
+
+#include <linux/sched.h>
+#include <linux/jump_label.h>
+
+#define IA32_PQR_ASSOC 0x0c8f
+
+/**
+ * struct resctrl_pqr_state - State cache for the PQR MSR
+ * @cur_rmid: The cached Resource Monitoring ID
+ * @cur_closid: The cached Class Of Service ID
+ * @default_rmid: The user assigned Resource Monitoring ID
+ * @default_closid: The user assigned cached Class Of Service ID
+ *
+ * The upper 32 bits of IA32_PQR_ASSOC contain closid and the
+ * lower 10 bits rmid. The update to IA32_PQR_ASSOC always
+ * contains both parts, so we need to cache them. This also
+ * stores the user configured per cpu CLOSID and RMID.
+ *
+ * The cache also helps to avoid pointless updates if the value does
+ * not change.
+ */
+struct resctrl_pqr_state {
+ u32 cur_rmid;
+ u32 cur_closid;
+ u32 default_rmid;
+ u32 default_closid;
+};
+
+DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
+
+DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
+DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
+DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
+
+/*
+ * __resctrl_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 __resctrl_sched_in(void)
+{
+ struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
+ u32 closid = state->default_closid;
+ u32 rmid = 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(&rdt_alloc_enable_key)) {
+ if (current->closid)
+ closid = current->closid;
+ }
+
+ if (static_branch_likely(&rdt_mon_enable_key)) {
+ if (current->rmid)
+ rmid = current->rmid;
+ }
+
+ if (closid != state->cur_closid || rmid != state->cur_rmid) {
+ state->cur_closid = closid;
+ state->cur_rmid = rmid;
+ wrmsr(IA32_PQR_ASSOC, rmid, closid);
+ }
+}
+
+static inline void resctrl_sched_in(void)
+{
+ if (static_branch_likely(&rdt_enable_key))
+ __resctrl_sched_in();
+}
+
+void resctrl_cpu_detect(struct cpuinfo_x86 *c);
+
+#else
+
+static inline void resctrl_sched_in(void) {}
+static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {}
+
+#endif /* CONFIG_X86_CPU_RESCTRL */
+
+#endif /* _ASM_X86_RESCTRL_H */