[PATCH v4 23/24] x86/resctrl: Expand resctrl_arch_update_domains()'s msr_param range

From: James Morse
Date: Mon Jun 14 2021 - 16:11:13 EST


resctrl_arch_update_domains() specifies the one closid that has
been modified and needs copying to the hardware.
resctrl_arch_update_domains() takes a struct rdt_resource and a
closid as arguments, but copies all the staged configurations
for that closid into the ctrl_val[] array.

resctrl_arch_update_domains() is called once per schema, but
once the resources and domains are merged, the second call of
a L2CODE/L2DATA pair will find no staged configurations, as
they were previously applied. The msr_param of the first call
only has one index, so would only have update the hardware
for the last staged configuration.

To avoid a second round of IPIs when changing L2CODE and L2DATA
in one go, expand the range of the msr_param if multiple staged
configurations are found.

Signed-off-by: James Morse <james.morse@xxxxxxx>
---
No changes since v3.

Changes since v2:
* This patch is new.
---
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index e384398374da..0a1b878ca0db 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -292,6 +292,7 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
return -ENOMEM;

mba_sc = is_mba_sc(r);
+ msr_param.res = NULL;
list_for_each_entry(d, &r->domains, list) {
hw_dom = resctrl_to_arch_dom(d);
for (t = 0; t < CDP_NUM_TYPES; t++) {
@@ -303,9 +304,14 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
if (!apply_config(hw_dom, cfg, idx, cpu_mask, mba_sc))
continue;

- msr_param.low = idx;
- msr_param.high = msr_param.low + 1;
- msr_param.res = r;
+ if (!msr_param.res) {
+ msr_param.low = idx;
+ msr_param.high = msr_param.low + 1;
+ msr_param.res = r;
+ } else {
+ msr_param.low = min(msr_param.low, idx);
+ msr_param.high = max(msr_param.high, idx + 1);
+ }
}
}

--
2.30.2