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x86/intel_rdt: Update percpu closid immeditately on CPUs affected by changee

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If CPUs are moved to or removed from a rdtgroup, the percpu closid storage
is updated. If tasks running on an affected CPU use the percpu closid then
the PQR_ASSOC MSR is only updated when the task runs through a context
switch. Up to the context switch the CPUs operate on the wrong closid. This
state is potentially unbound.
    
Make the change immediately effective by invoking a smp function call on
the affected CPUs which stores the new closid in the perpu storage and
calls the rdt_sched_in() function which updates the MSR, if the current
task uses the percpu closid.

[ tglx: Made it work and massaged changelog once more ]

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "Ingo Molnar" <mingo@elte.hu>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1478912558-55514-3-git-send-email-fenghua.yu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Fenghua Yu 2016-11-11 17:02:38 -08:00 committed by Thomas Gleixner
parent c7cc0cc10c
commit f410770293
1 changed files with 36 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

72
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
View File

@ -191,12 +191,40 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
return ret;
}
/*
* This is safe against intel_rdt_sched_in() called from __switch_to()
* because __switch_to() is executed with interrupts disabled. A local call
* from rdt_update_percpu_closid() is proteced against __switch_to() because
* preemption is disabled.
*/
static void rdt_update_cpu_closid(void *v)
{
this_cpu_write(cpu_closid, *(int *)v);
/*
* We cannot unconditionally write the MSR because the current
* executing task might have its own closid selected. Just reuse
* the context switch code.
*/
intel_rdt_sched_in();
}
/* Update the per cpu closid and eventually the PGR_ASSOC MSR */
static void rdt_update_percpu_closid(const struct cpumask *cpu_mask, int closid)
{
int cpu = get_cpu();
if (cpumask_test_cpu(cpu, cpu_mask))
rdt_update_cpu_closid(&closid);
smp_call_function_many(cpu_mask, rdt_update_cpu_closid, &closid, 1);
put_cpu();
}
static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
cpumask_var_t tmpmask, newmask;
struct rdtgroup *rdtgrp, *r;
int ret, cpu;
int ret;
if (!buf)
return -EINVAL;
@ -236,8 +264,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
/* Give any dropped cpus to rdtgroup_default */
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, tmpmask);
for_each_cpu(cpu, tmpmask)
per_cpu(cpu_closid, cpu) = 0;
rdt_update_percpu_closid(tmpmask, rdtgroup_default.closid);
}
/*
@ -251,8 +278,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
continue;
cpumask_andnot(&r->cpu_mask, &r->cpu_mask, tmpmask);
}
for_each_cpu(cpu, tmpmask)
per_cpu(cpu_closid, cpu) = rdtgrp->closid;
rdt_update_percpu_closid(tmpmask, rdtgroup_default.closid);
}
/* Done pushing/pulling - update this group with new mask */
@ -780,18 +806,6 @@ static int reset_all_cbms(struct rdt_resource *r)
return 0;
}
/*
* MSR_IA32_PQR_ASSOC is scoped per logical CPU, so all updates
* are always in thread context.
*/
static void rdt_reset_pqr_assoc_closid(void *v)
{
struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
state->closid = 0;
wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, 0);
}
/*
* Forcibly remove all of subdirectories under root.
*/
@ -799,7 +813,6 @@ static void rmdir_all_sub(void)
{
struct rdtgroup *rdtgrp, *tmp;
struct task_struct *p, *t;
int cpu;
/* move all tasks to default resource group */
read_lock(&tasklist_lock);
@ -807,14 +820,6 @@ static void rmdir_all_sub(void)
t->closid = 0;
read_unlock(&tasklist_lock);
get_cpu();
/* Reset PQR_ASSOC MSR on this cpu. */
rdt_reset_pqr_assoc_closid(NULL);
/* Reset PQR_ASSOC MSR on the rest of cpus. */
smp_call_function_many(cpu_online_mask, rdt_reset_pqr_assoc_closid,
NULL, 1);
put_cpu();
list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
/* Remove each rdtgroup other than root */
if (rdtgrp == &rdtgroup_default)
@ -828,15 +833,13 @@ static void rmdir_all_sub(void)
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
rdt_update_percpu_closid(&rdtgrp->cpu_mask,
rdtgroup_default.closid);
kernfs_remove(rdtgrp->kn);
list_del(&rdtgrp->rdtgroup_list);
kfree(rdtgrp);
}
/* Reset all per cpu closids to the default value */
for_each_cpu(cpu, &rdtgroup_default.cpu_mask)
per_cpu(cpu_closid, cpu) = 0;
kernfs_remove(kn_info);
}
@ -943,7 +946,6 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
{
struct task_struct *p, *t;
struct rdtgroup *rdtgrp;
int cpu, ret = 0;
rdtgrp = rdtgroup_kn_lock_live(kn);
if (!rdtgrp) {
@ -962,8 +964,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
/* Give any CPUs back to the default group */
cpumask_or(&rdtgroup_default.cpu_mask,
&rdtgroup_default.cpu_mask, &rdtgrp->cpu_mask);
for_each_cpu(cpu, &rdtgrp->cpu_mask)
per_cpu(cpu_closid, cpu) = 0;
rdt_update_percpu_closid(&rdtgrp->cpu_mask, rdtgroup_default.closid);
rdtgrp->flags = RDT_DELETED;
closid_free(rdtgrp->closid);
@ -977,8 +978,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn)
kernfs_remove(rdtgrp->kn);
rdtgroup_kn_unlock(kn);
return ret;
return 0;
}
static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {