Commit e557999f authored by James Morse's avatar James Morse Committed by Borislav Petkov (AMD)
Browse files

x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read() 



Depending on the number of monitors available, Arm's MPAM may need to
allocate a monitor prior to reading the counter value. Allocating a
contended resource may involve sleeping.

__check_limbo() and mon_event_count() each make multiple calls to
resctrl_arch_rmid_read(), to avoid extra work on contended systems,
the allocation should be valid for multiple invocations of
resctrl_arch_rmid_read().

The memory or hardware allocated is not specific to a domain.

Add arch hooks for this allocation, which need calling before
resctrl_arch_rmid_read(). The allocated monitor is passed to
resctrl_arch_rmid_read(), then freed again afterwards. The helper
can be called on any CPU, and can sleep.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Reviewed-by: default avatarBabu Moger <babu.moger@amd.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: default avatarPeter Newman <peternewman@google.com>
Tested-by: default avatarBabu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-16-james.morse@arm.com


Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
parent 6fde1424

arch/x86/include/asm/resctrl.h

+11 −0
Original line number Diff line number Diff line
@@ -136,6 +136,17 @@ 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

arch/x86/kernel/cpu/resctrl/ctrlmondata.c

+7 −0
Original line number Diff line number Diff line
@@ -546,6 +546,11 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r, 
	rr->d = d;

	rr->val = 0;

	rr->first = first;

	rr->arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, evtid);

	if (IS_ERR(rr->arch_mon_ctx)) {

		rr->err = -EINVAL;

		return;

	}



	cpu = cpumask_any_housekeeping(&d->cpu_mask);
@@ -559,6 +564,8 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r, 
		smp_call_function_any(&d->cpu_mask, mon_event_count, rr, 1);

	else

		smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);



	resctrl_arch_mon_ctx_free(r, evtid, rr->arch_mon_ctx);

}



int rdtgroup_mondata_show(struct seq_file *m, void *arg)

arch/x86/kernel/cpu/resctrl/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -137,6 +137,7 @@ struct rmid_read { 
	bool			first;

	int			err;

	u64			val;

	void			*arch_mon_ctx;

};



extern bool rdt_alloc_capable;

arch/x86/kernel/cpu/resctrl/monitor.c

+32 −3
Original line number Diff line number Diff line
@@ -269,7 +269,7 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width) 


int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,

			   u32 unused, u32 rmid, enum resctrl_event_id eventid,

			   u64 *val)

			   u64 *val, void *ignored)

{

	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);

	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
@@ -324,9 +324,17 @@ void __check_limbo(struct rdt_domain *d, bool force_free) 
	u32 idx_limit = resctrl_arch_system_num_rmid_idx();

	struct rmid_entry *entry;

	u32 idx, cur_idx = 1;

	void *arch_mon_ctx;

	bool rmid_dirty;

	u64 val = 0;



	arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, QOS_L3_OCCUP_EVENT_ID);

	if (IS_ERR(arch_mon_ctx)) {

		pr_warn_ratelimited("Failed to allocate monitor context: %ld",

				    PTR_ERR(arch_mon_ctx));

		return;

	}



	/*

	 * Skip RMID 0 and start from RMID 1 and check all the RMIDs that

	 * are marked as busy for occupancy < threshold. If the occupancy
@@ -340,7 +348,8 @@ void __check_limbo(struct rdt_domain *d, bool force_free) 


		entry = __rmid_entry(idx);

		if (resctrl_arch_rmid_read(r, d, entry->closid, entry->rmid,

					   QOS_L3_OCCUP_EVENT_ID, &val)) {

					   QOS_L3_OCCUP_EVENT_ID, &val,

					   arch_mon_ctx)) {

			rmid_dirty = true;

		} else {

			rmid_dirty = (val >= resctrl_rmid_realloc_threshold);
@@ -353,6 +362,8 @@ void __check_limbo(struct rdt_domain *d, bool force_free) 
		}

		cur_idx = idx + 1;

	}



	resctrl_arch_mon_ctx_free(r, QOS_L3_OCCUP_EVENT_ID, arch_mon_ctx);

}



bool has_busy_rmid(struct rdt_domain *d)
@@ -533,7 +544,7 @@ static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr) 
	}



	rr->err = resctrl_arch_rmid_read(rr->r, rr->d, closid, rmid, rr->evtid,

					 &tval);

					 &tval, rr->arch_mon_ctx);

	if (rr->err)

		return rr->err;
@@ -722,11 +733,27 @@ static void mbm_update(struct rdt_resource *r, struct rdt_domain *d, 
	if (is_mbm_total_enabled()) {

		rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID;

		rr.val = 0;

		rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);

		if (IS_ERR(rr.arch_mon_ctx)) {

			pr_warn_ratelimited("Failed to allocate monitor context: %ld",

					    PTR_ERR(rr.arch_mon_ctx));

			return;

		}



		__mon_event_count(closid, rmid, &rr);



		resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);

	}

	if (is_mbm_local_enabled()) {

		rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;

		rr.val = 0;

		rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);

		if (IS_ERR(rr.arch_mon_ctx)) {

			pr_warn_ratelimited("Failed to allocate monitor context: %ld",

					    PTR_ERR(rr.arch_mon_ctx));

			return;

		}



		__mon_event_count(closid, rmid, &rr);



		/*
@@ -736,6 +763,8 @@ static void mbm_update(struct rdt_resource *r, struct rdt_domain *d, 
		 */

		if (is_mba_sc(NULL))

			mbm_bw_count(closid, rmid, &rr);



		resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);

	}

}

include/linux/resctrl.h

+4 −1
Original line number Diff line number Diff line
@@ -235,6 +235,9 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d); 
 * @rmid:		rmid of the counter to read.

 * @eventid:		eventid to read, e.g. L3 occupancy.

 * @val:		result of the counter read in bytes.

 * @arch_mon_ctx:	An architecture specific value from

 *			resctrl_arch_mon_ctx_alloc(), for MPAM this identifies

 *			the hardware monitor allocated for this read request.

 *

 * Some architectures need to sleep when first programming some of the counters.

 * (specifically: arm64's MPAM cache occupancy counters can return 'not ready'
@@ -248,7 +251,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d); 
 */

int resctrl_arch_rmid_read(struct rdt_resource *r, struct rdt_domain *d,

			   u32 closid, u32 rmid, enum resctrl_event_id eventid,

			   u64 *val);

			   u64 *val, void *arch_mon_ctx);



/**

 * resctrl_arch_rmid_read_context_check()  - warn about invalid contexts