[tip: x86/cache] x86/resctrl: Expand resctrl_arch_update_domains()'s msr_param range

[tip-bot2 for James Morse]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     327364d5b6b6f8c89d2d6253a986d80323512890
Gitweb:        https://git.kernel.org/tip/327364d5b6b6f8c89d2d6253a986d80323512890
Author:        James Morse <james.morse@xxxxxxx>
AuthorDate:    Wed, 28 Jul 2021 17:06:36 
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 11 Aug 2021 18:37:02 +02:00

x86/resctrl: Expand resctrl_arch_update_domains()'s msr_param range

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>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Link: https://lkml.kernel.org/r/20210728170637.25610-24-james.morse@xxxxxxx
---
 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 92d79c8..a487cf7 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);
+			}
 		}
 	}