From: Reinette Chatre <reinette.chatre@intel.com>
To: tglx@linutronix.de, fenghua.yu@intel.com, bp@alien8.de,
tony.luck@intel.com
Cc: kuo-lang.tseng@intel.com, shakeelb@google.com,
valentin.schneider@arm.com, mingo@redhat.com, babu.moger@amd.com,
james.morse@arm.com, hpa@zytor.com, x86@kernel.org,
linux-kernel@vger.kernel.org,
Reinette Chatre <reinette.chatre@intel.com>
Subject: [PATCH V2 4/4] x86/resctrl: Apply READ_ONCE/WRITE_ONCE to task_struct .rmid & .closid
Date: Thu, 17 Dec 2020 14:31:21 -0800 [thread overview]
Message-ID: <9921fda88ad81afb9885b517fbe864a2bc7c35a9.1608243147.git.reinette.chatre@intel.com> (raw)
In-Reply-To: <cover.1608243147.git.reinette.chatre@intel.com>
From: Valentin Schneider <valentin.schneider@arm.com>
A CPU's current task can have its {closid, rmid} fields read locally while
they are being concurrently written to from another CPU. This can happen
anytime __resctrl_sched_in() races with either __rdtgroup_move_task() or
rdt_move_group_tasks().
Prevent load / store tearing for those accesses by giving them the
READ_ONCE() / WRITE_ONCE() treatment.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
V1->V2:
* Subject line prefix x86/intel_rdt -> x86/resctrl. (Reinette)
arch/x86/include/asm/resctrl.h | 11 +++++++----
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 10 +++++-----
2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 07603064df8f..d60ed0668a59 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -56,19 +56,22 @@ static void __resctrl_sched_in(void)
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)) {
- if (current->closid)
- closid = current->closid;
+ tmp = READ_ONCE(current->closid);
+ if (tmp)
+ closid = tmp;
}
if (static_branch_likely(&rdt_mon_enable_key)) {
- if (current->rmid)
- rmid = current->rmid;
+ tmp = READ_ONCE(current->rmid);
+ if (tmp)
+ rmid = tmp;
}
if (closid != state->cur_closid || rmid != state->cur_rmid) {
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 9bd36210d220..5aeb4fb91228 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -569,11 +569,11 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
*/
if (rdtgrp->type == RDTCTRL_GROUP) {
- tsk->closid = rdtgrp->closid;
- tsk->rmid = rdtgrp->mon.rmid;
+ WRITE_ONCE(tsk->closid, rdtgrp->closid);
+ WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
} else if (rdtgrp->type == RDTMON_GROUP) {
if (rdtgrp->mon.parent->closid == tsk->closid) {
- tsk->rmid = rdtgrp->mon.rmid;
+ WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
} else {
rdt_last_cmd_puts("Can't move task to different control group\n");
return -EINVAL;
@@ -2316,8 +2316,8 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
for_each_process_thread(p, t) {
if (!from || is_closid_match(t, from) ||
is_rmid_match(t, from)) {
- t->closid = to->closid;
- t->rmid = to->mon.rmid;
+ WRITE_ONCE(t->closid, to->closid);
+ WRITE_ONCE(t->rmid, to->mon.rmid);
/*
* If the task is on a CPU, set the CPU in the mask.
--
2.26.2
prev parent reply other threads:[~2020-12-17 22:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 22:31 [PATCH V2 0/4] x86/resctrl: Fix a few issues in moving a task to a resource group Reinette Chatre
2020-12-17 22:31 ` [PATCH V2 1/4] x86/resctrl: Use IPI instead of task_work_add() to update PQR_ASSOC MSR Reinette Chatre
2021-01-06 11:19 ` Borislav Petkov
2021-01-07 22:11 ` Reinette Chatre
2020-12-17 22:31 ` [PATCH V2 2/4] x86/resctrl: Don't move a task to the same resource group Reinette Chatre
2020-12-17 22:31 ` [PATCH V2 3/4] x86/resctrl: Use task_curr() instead of task_struct->on_cpu to prevent unnecessary IPI Reinette Chatre
2020-12-17 22:31 ` Reinette Chatre [this message]
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