[PATCH V2 2/9] x86/intel_rdt: Fix size reporting of MBA resource
From: Reinette Chatre
Chen Yu reported a divide-by-zero error when accessing the 'size'
resctrl file when a MBA resource is enabled.
divide error: [#1] SMP PTI
CPU: 93 PID: 1929 Comm: cat Not tainted 4.19.0-rc2-debug-rdt+ #25
RIP: 0010:rdtgroup_cbm_to_size+0x7e/0xa0
Call Trace:
rdtgroup_size_show+0x11a/0x1d0
seq_read+0xd8/0x3b0
Quoting Chen Yu's report: This is because for MB resource,
the r->cache.cbm_len is zero, thus calculating size in
rdtgroup_cbm_to_size() will trigger the exception.
Fix this issue in the 'size' file by getting correct memory bandwidth
value which is in MBps when MBA software controller is enabled or in
percentage when MBA software controller is disabled.
Fixes: d9b48c86eb38 ("x86/intel_rdt: Display resource groups' allocations in
bytes")
Link: https://lkml.kernel.org/r/20180904174614.26682-1-yu.c.c...@intel.com
Reported-by: Chen Yu
Tested-by: Chen Yu
Signed-off-by: Reinette Chatre
Signed-off-by: Fenghua Yu
---
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 14 ++
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index b799c00bef09..32e8bbdf2400 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1155,8 +1155,8 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
struct rdt_resource *r;
struct rdt_domain *d;
unsigned int size;
- bool sep = false;
- u32 cbm;
+ bool sep;
+ u32 ctrl;
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
@@ -1174,6 +1174,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
}
for_each_alloc_enabled_rdt_resource(r) {
+ sep = false;
seq_printf(s, "%*s:", max_name_width, r->name);
list_for_each_entry(d, >domains, list) {
if (sep)
@@ -1181,8 +1182,13 @@ static int rdtgroup_size_show(struct kernfs_open_file
*of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
size = 0;
} else {
- cbm = d->ctrl_val[rdtgrp->closid];
- size = rdtgroup_cbm_to_size(r, d, cbm);
+ ctrl = (!is_mba_sc(r) ?
+ d->ctrl_val[rdtgrp->closid] :
+ d->mbps_val[rdtgrp->closid]);
+ if (r->rid == RDT_RESOURCE_MBA)
+ size = ctrl;
+ else
+ size = rdtgroup_cbm_to_size(r, d, ctrl);
}
seq_printf(s, "%d=%u", d->id, size);
sep = true;
--
2.19.0
[PATCH V2 2/9] x86/intel_rdt: Fix size reporting of MBA resource
From: Reinette Chatre
Chen Yu reported a divide-by-zero error when accessing the 'size'
resctrl file when a MBA resource is enabled.
divide error: [#1] SMP PTI
CPU: 93 PID: 1929 Comm: cat Not tainted 4.19.0-rc2-debug-rdt+ #25
RIP: 0010:rdtgroup_cbm_to_size+0x7e/0xa0
Call Trace:
rdtgroup_size_show+0x11a/0x1d0
seq_read+0xd8/0x3b0
Quoting Chen Yu's report: This is because for MB resource,
the r->cache.cbm_len is zero, thus calculating size in
rdtgroup_cbm_to_size() will trigger the exception.
Fix this issue in the 'size' file by getting correct memory bandwidth
value which is in MBps when MBA software controller is enabled or in
percentage when MBA software controller is disabled.
Fixes: d9b48c86eb38 ("x86/intel_rdt: Display resource groups' allocations in
bytes")
Link: https://lkml.kernel.org/r/20180904174614.26682-1-yu.c.c...@intel.com
Reported-by: Chen Yu
Tested-by: Chen Yu
Signed-off-by: Reinette Chatre
Signed-off-by: Fenghua Yu
---
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 14 ++
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index b799c00bef09..32e8bbdf2400 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -1155,8 +1155,8 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
struct rdt_resource *r;
struct rdt_domain *d;
unsigned int size;
- bool sep = false;
- u32 cbm;
+ bool sep;
+ u32 ctrl;
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
@@ -1174,6 +1174,7 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
}
for_each_alloc_enabled_rdt_resource(r) {
+ sep = false;
seq_printf(s, "%*s:", max_name_width, r->name);
list_for_each_entry(d, >domains, list) {
if (sep)
@@ -1181,8 +1182,13 @@ static int rdtgroup_size_show(struct kernfs_open_file
*of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
size = 0;
} else {
- cbm = d->ctrl_val[rdtgrp->closid];
- size = rdtgroup_cbm_to_size(r, d, cbm);
+ ctrl = (!is_mba_sc(r) ?
+ d->ctrl_val[rdtgrp->closid] :
+ d->mbps_val[rdtgrp->closid]);
+ if (r->rid == RDT_RESOURCE_MBA)
+ size = ctrl;
+ else
+ size = rdtgroup_cbm_to_size(r, d, ctrl);
}
seq_printf(s, "%d=%u", d->id, size);
sep = true;
--
2.19.0
