[PATCH 4.19 33/40] x86/resctrl: Preserve CDP enable over CPU hotplug

From: Greg Kroah-Hartman
Date: Mon Apr 20 2020 - 08:50:43 EST


From: James Morse <james.morse@xxxxxxx>

commit 9fe0450785abbc04b0ed5d3cf61fcdb8ab656b4b upstream.

Resctrl assumes that all CPUs are online when the filesystem is mounted,
and that CPUs remember their CDP-enabled state over CPU hotplug.

This goes wrong when resctrl's CDP-enabled state changes while all the
CPUs in a domain are offline.

When a domain comes online, enable (or disable!) CDP to match resctrl's
current setting.

Fixes: 5ff193fbde20 ("x86/intel_rdt: Add basic resctrl filesystem support")
Suggested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200221162105.154163-1-james.morse@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/x86/kernel/cpu/intel_rdt.c | 2 ++
arch/x86/kernel/cpu/intel_rdt.h | 1 +
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 13 +++++++++++++
3 files changed, 16 insertions(+)

--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -555,6 +555,8 @@ static void domain_add_cpu(int cpu, stru
d->id = id;
cpumask_set_cpu(cpu, &d->cpu_mask);

+ rdt_domain_reconfigure_cdp(r);
+
if (r->alloc_capable && domain_setup_ctrlval(r, d)) {
kfree(d);
return;
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -567,5 +567,6 @@ void cqm_setup_limbo_handler(struct rdt_
void cqm_handle_limbo(struct work_struct *work);
bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
void __check_limbo(struct rdt_domain *d, bool force_free);
+void rdt_domain_reconfigure_cdp(struct rdt_resource *r);

#endif /* _ASM_X86_INTEL_RDT_H */
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1777,6 +1777,19 @@ static int set_cache_qos_cfg(int level,
return 0;
}

+/* Restore the qos cfg state when a domain comes online */
+void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
+{
+ if (!r->alloc_capable)
+ return;
+
+ if (r == &rdt_resources_all[RDT_RESOURCE_L2DATA])
+ l2_qos_cfg_update(&r->alloc_enabled);
+
+ if (r == &rdt_resources_all[RDT_RESOURCE_L3DATA])
+ l3_qos_cfg_update(&r->alloc_enabled);
+}
+
/*
* Enable or disable the MBA software controller
* which helps user specify bandwidth in MBps.