Commit 4d044c52 authored by James Morse's avatar James Morse Committed by Borislav Petkov
Browse files

x86/resctrl: Abstract __rmid_read() 



__rmid_read() selects the specified eventid and returns the counter
value from the MSR. The error handling is architecture specific, and
handled by the callers, rdtgroup_mondata_show() and __mon_event_count().

Error handling should be handled by architecture specific code, as
a different architecture may have different requirements. MPAM's
counters can report that they are 'not ready', requiring a second
read after a short delay. This should be hidden from resctrl.

Make __rmid_read() the architecture specific function for reading
a counter. Rename it resctrl_arch_rmid_read() and move the error
handling into it.

A read from a counter that hardware supports but resctrl does not
now returns -EINVAL instead of -EIO from the default case in
__mon_event_count(). It isn't possible for user-space to see this
change as resctrl doesn't expose counters it doesn't support.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarJamie Iles <quic_jiles@quicinc.com>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Tested-by: default avatarXin Hao <xhao@linux.alibaba.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20220902154829.30399-16-james.morse@arm.com
parent fea62d37

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

+2 −2
Original line number Diff line number Diff line
@@ -579,9 +579,9 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg) 


	mon_event_read(&rr, r, d, rdtgrp, evtid, false);



	if (rr.val & RMID_VAL_ERROR)

	if (rr.err == -EIO)

		seq_puts(m, "Error\n");

	else if (rr.val & RMID_VAL_UNAVAIL)

	else if (rr.err == -EINVAL)

		seq_puts(m, "Unavailable\n");

	else

		seq_printf(m, "%llu\n", rr.val * hw_res->mon_scale);

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

+1 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ struct rmid_read { 
	struct rdt_domain	*d;

	enum resctrl_event_id	evtid;

	bool			first;

	int			err;

	u64			val;

};

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

+39 −23
Original line number Diff line number Diff line
@@ -167,9 +167,9 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d, 
		memset(am, 0, sizeof(*am));

}



static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid)

int resctrl_arch_rmid_read(u32 rmid, enum resctrl_event_id eventid, u64 *val)

{

	u64 val;

	u64 msr_val;



	/*

	 * As per the SDM, when IA32_QM_EVTSEL.EvtID (bits 7:0) is configured
@@ -180,14 +180,24 @@ static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid) 
	 * are error bits.

	 */

	wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid);

	rdmsrl(MSR_IA32_QM_CTR, val);

	rdmsrl(MSR_IA32_QM_CTR, msr_val);



	return val;

	if (msr_val & RMID_VAL_ERROR)

		return -EIO;

	if (msr_val & RMID_VAL_UNAVAIL)

		return -EINVAL;



	*val = msr_val;



	return 0;

}



static bool rmid_dirty(struct rmid_entry *entry)

{

	u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);

	u64 val = 0;



	if (resctrl_arch_rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID, &val))

		return true;



	return val >= resctrl_cqm_threshold;

}
@@ -259,8 +269,8 @@ static void add_rmid_to_limbo(struct rmid_entry *entry) 
{

	struct rdt_resource *r;

	struct rdt_domain *d;

	int cpu;

	u64 val;

	int cpu, err;

	u64 val = 0;



	r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
@@ -268,8 +278,10 @@ static void add_rmid_to_limbo(struct rmid_entry *entry) 
	cpu = get_cpu();

	list_for_each_entry(d, &r->domains, list) {

		if (cpumask_test_cpu(cpu, &d->cpu_mask)) {

			val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);

			if (val <= resctrl_cqm_threshold)

			err = resctrl_arch_rmid_read(entry->rmid,

						     QOS_L3_OCCUP_EVENT_ID,

						     &val);

			if (err || val <= resctrl_cqm_threshold)

				continue;

		}
@@ -315,19 +327,19 @@ static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width) 
	return chunks >> shift;

}



static u64 __mon_event_count(u32 rmid, struct rmid_read *rr)

static int __mon_event_count(u32 rmid, struct rmid_read *rr)

{

	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);

	struct mbm_state *m;

	u64 chunks, tval;

	u64 chunks, tval = 0;



	if (rr->first)

		resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);



	tval = __rmid_read(rmid, rr->evtid);

	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {

		return tval;

	}

	rr->err = resctrl_arch_rmid_read(rmid, rr->evtid, &tval);

	if (rr->err)

		return rr->err;



	switch (rr->evtid) {

	case QOS_L3_OCCUP_EVENT_ID:

		rr->val += tval;
@@ -341,9 +353,9 @@ static u64 __mon_event_count(u32 rmid, struct rmid_read *rr) 
	default:

		/*

		 * Code would never reach here because an invalid

		 * event id would fail the __rmid_read.

		 * event id would fail in resctrl_arch_rmid_read().

		 */

		return RMID_VAL_ERROR;

		return -EINVAL;

	}



	if (rr->first) {
@@ -399,11 +411,11 @@ void mon_event_count(void *info) 
	struct rdtgroup *rdtgrp, *entry;

	struct rmid_read *rr = info;

	struct list_head *head;

	u64 ret_val;

	int ret;



	rdtgrp = rr->rgrp;



	ret_val = __mon_event_count(rdtgrp->mon.rmid, rr);

	ret = __mon_event_count(rdtgrp->mon.rmid, rr);



	/*

	 * For Ctrl groups read data from child monitor groups and
@@ -415,13 +427,17 @@ void mon_event_count(void *info) 
	if (rdtgrp->type == RDTCTRL_GROUP) {

		list_for_each_entry(entry, head, mon.crdtgrp_list) {

			if (__mon_event_count(entry->mon.rmid, rr) == 0)

				ret_val = 0;

				ret = 0;

		}

	}



	/* Report error if none of rmid_reads are successful */

	if (ret_val)

		rr->val = ret_val;

	/*

	 * __mon_event_count() calls for newly created monitor groups may

	 * report -EINVAL/Unavailable if the monitor hasn't seen any traffic.

	 * Discard error if any of the monitor event reads succeeded.

	 */

	if (ret == 0)

		rr->err = 0;

}



/*

include/linux/resctrl.h

+1 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d, 
			    u32 closid, enum resctrl_conf_type type);

int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d);

void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);

int resctrl_arch_rmid_read(u32 rmid, enum resctrl_event_id eventid, u64 *res);



/**

 * resctrl_arch_reset_rmid() - Reset any private state associated with rmid