Commit 475228d1 authored by James Morse's avatar James Morse Committed by Catalin Marinas
Browse files

arm_mpam: Add a helper to touch an MSC from any CPU 



Resetting RIS entries from the cpuhp callback is easy as the
callback occurs on the correct CPU. This won't be true for any other
caller that wants to reset or configure an MSC.

Add a helper that schedules the provided function if necessary.

Callers should take the cpuhp lock to prevent the cpuhp callbacks from
changing the MSC state.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarBen Horgan <ben.horgan@arm.com>
Reviewed-by: default avatarJonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: default avatarFenghua Yu <fenghuay@nvidia.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: default avatarFenghua Yu <fenghuay@nvidia.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: default avatarPeter Newman <peternewman@google.com>
Tested-by: default avatarCarl Worth <carl@os.amperecomputing.com>
Tested-by: default avatarGavin Shan <gshan@redhat.com>
Tested-by: default avatarZeng Heng <zengheng4@huawei.com>
Tested-by: default avatarHanjun Guo <guohanjun@huawei.com>
Signed-off-by: default avatarBen Horgan <ben.horgan@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent f188a36c

drivers/resctrl/mpam_devices.c

+34 −3
Original line number Diff line number Diff line
@@ -806,20 +806,51 @@ static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 partid) 
	mutex_unlock(&msc->part_sel_lock);

}



static void mpam_reset_ris(struct mpam_msc_ris *ris)

/*

 * Called via smp_call_on_cpu() to prevent migration, while still being

 * pre-emptible.

 */

static int mpam_reset_ris(void *arg)

{

	u16 partid, partid_max;

	struct mpam_msc_ris *ris = arg;



	WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu)));



	if (ris->in_reset_state)

		return;

		return 0;



	spin_lock(&partid_max_lock);

	partid_max = mpam_partid_max;

	spin_unlock(&partid_max_lock);

	for (partid = 0; partid <= partid_max; partid++)

		mpam_reset_ris_partid(ris, partid);



	return 0;

}



/*

 * Get the preferred CPU for this MSC. If it is accessible from this CPU,

 * this CPU is preferred. This can be preempted/migrated, it will only result

 * in more work.

 */

static int mpam_get_msc_preferred_cpu(struct mpam_msc *msc)

{

	int cpu = raw_smp_processor_id();



	if (cpumask_test_cpu(cpu, &msc->accessibility))

		return cpu;



	return cpumask_first_and(&msc->accessibility, cpu_online_mask);

}



static int mpam_touch_msc(struct mpam_msc *msc, int (*fn)(void *a), void *arg)

{

	lockdep_assert_irqs_enabled();

	lockdep_assert_cpus_held();

	WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu)));



	return smp_call_on_cpu(mpam_get_msc_preferred_cpu(msc), fn, arg, true);

}



static void mpam_reset_msc(struct mpam_msc *msc, bool online)
@@ -827,7 +858,7 @@ static void mpam_reset_msc(struct mpam_msc *msc, bool online) 
	struct mpam_msc_ris *ris;



	list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&mpam_srcu)) {

		mpam_reset_ris(ris);

		mpam_touch_msc(msc, &mpam_reset_ris, ris);



		/*

		 * Set in_reset_state when coming online. The reset state