arch/x86/include/asm/resctrl.h

/* 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>

/*
 * This value can never be a valid CLOSID, and is used when mapping a
 * (closid, rmid) pair to an index and back. On x86 only the RMID is
 * needed. The index is a software defined value.
 */
#define X86_RESCTRL_EMPTY_CLOSID         ((u32)~0)

/**
 * 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 MSR_IA32_PQR_ASSOC contain closid and the
 * lower 10 bits rmid. The update to MSR_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);

extern bool rdt_alloc_capable;
extern bool rdt_mon_capable;

DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);

static inline bool resctrl_arch_alloc_capable(void)
{
	return rdt_alloc_capable;
}

static inline void resctrl_arch_enable_alloc(void)
{
	static_branch_enable_cpuslocked(&rdt_alloc_enable_key);
	static_branch_inc_cpuslocked(&rdt_enable_key);
}

static inline void resctrl_arch_disable_alloc(void)
{
	static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
	static_branch_dec_cpuslocked(&rdt_enable_key);
}

static inline bool resctrl_arch_mon_capable(void)
{
	return rdt_mon_capable;
}

static inline void resctrl_arch_enable_mon(void)
{
	static_branch_enable_cpuslocked(&rdt_mon_enable_key);
	static_branch_inc_cpuslocked(&rdt_enable_key);
}

static inline void resctrl_arch_disable_mon(void)
{
	static_branch_disable_cpuslocked(&rdt_mon_enable_key);
	static_branch_dec_cpuslocked(&rdt_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 inline void __resctrl_sched_in(struct task_struct *tsk)
{
	struct resctrl_pqr_state *state = this_cpu_ptr(&pqr_state);
	u32 closid = state->default_closid;
	u32 rmid = state->default_rmid;
	u32 tmp;

	/*
	 * 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)) {
		tmp = READ_ONCE(tsk->closid);
		if (tmp)
			closid = tmp;
	}

	if (static_branch_likely(&rdt_mon_enable_key)) {
		tmp = READ_ONCE(tsk->rmid);
		if (tmp)
			rmid = tmp;
	}

	if (closid != state->cur_closid || rmid != state->cur_rmid) {
		state->cur_closid = closid;
		state->cur_rmid = rmid;
		wrmsr(MSR_IA32_PQR_ASSOC, rmid, closid);
	}
}

static inline unsigned int resctrl_arch_round_mon_val(unsigned int val)
{
	unsigned int scale = boot_cpu_data.x86_cache_occ_scale;

	/* h/w works in units of "boot_cpu_data.x86_cache_occ_scale" */
	val /= scale;
	return val * scale;
}

static inline void resctrl_arch_set_closid_rmid(struct task_struct *tsk,
						u32 closid, u32 rmid)
{
	WRITE_ONCE(tsk->closid, closid);
	WRITE_ONCE(tsk->rmid, rmid);
}

static inline bool resctrl_arch_match_closid(struct task_struct *tsk, u32 closid)
{
	return READ_ONCE(tsk->closid) == closid;
}

static inline bool resctrl_arch_match_rmid(struct task_struct *tsk, u32 ignored,
					   u32 rmid)
{
	return READ_ONCE(tsk->rmid) == rmid;
}

static inline void resctrl_sched_in(struct task_struct *tsk)
{
	if (static_branch_likely(&rdt_enable_key))
		__resctrl_sched_in(tsk);
}

static inline void resctrl_arch_rmid_idx_decode(u32 idx, u32 *closid, u32 *rmid)
{
	*rmid = idx;
	*closid = X86_RESCTRL_EMPTY_CLOSID;
}

static inline u32 resctrl_arch_rmid_idx_encode(u32 ignored, u32 rmid)
{
	return rmid;
}

/* x86 can always read an rmid, nothing needs allocating */
struct rdt_resource;
static inline void *resctrl_arch_mon_ctx_alloc(struct rdt_resource *r, int evtid)
{
	might_sleep();
	return NULL;
};

static inline void resctrl_arch_mon_ctx_free(struct rdt_resource *r, int evtid,
					     void *ctx) { };

void resctrl_cpu_detect(struct cpuinfo_x86 *c);

#else

static inline void resctrl_sched_in(struct task_struct *tsk) {}
static inline void resctrl_cpu_detect(struct cpuinfo_x86 *c) {}

#endif /* CONFIG_X86_CPU_RESCTRL */

#endif /* _ASM_X86_RESCTRL_H */