linux-kernel - [RFC PATCH 05/20] x86/intel_rdt: make update

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Message-Id: <20180824104519.11203-6-james.morse@arm.com>
Date:   Fri, 24 Aug 2018 11:45:04 +0100
From:   James Morse <james.morse@....com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>
Subject: [RFC PATCH 05/20] x86/intel_rdt: make update_domains() learn the affected closids

Now that the closid is present in the staged configuration,
update_domains() can learn which low/high values it should update.

Remove the single passed in closid, and update msr_param as we
apply each staged config.

Once the L2/L2CODE/L2DATA resources are merged this will allow
update_domains() to be called once for the single resource, even
when CDP is in use. This results in both CODE and DATA
configurations being applied and the two consecutive closids being
updated with a single smp_call_function_many().

This will let us keep the CDP odd/even behaviour inside resctrl
so that architectures that don't do this don't need to emulate it.

Signed-off-by: James Morse <james.morse@....com>
---
 arch/x86/kernel/cpu/intel_rdt.h             |  4 ++--
 arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 21 ++++++++++++++++-----
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 5e271e0fe1f5..8df549ef016d 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -241,8 +241,8 @@ static inline struct rdt_hw_domain *rc_dom_to_rdt(struct rdt_domain *r)
  */
 struct msr_param {
 	struct rdt_resource	*res;
-	int			low;
-	int			high;
+	u32			low;
+	u32			high;
 };
 
 static inline bool is_llc_occupancy_enabled(void)
diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index 0c849653a99d..01ffd455313a 100644
--- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
@@ -193,22 +193,21 @@ static void apply_config(struct rdt_hw_domain *hw_dom,
 	}
 }
 
-static int update_domains(struct rdt_resource *r, int closid)
+static int update_domains(struct rdt_resource *r)
 {
 	struct resctrl_staged_config *cfg;
 	struct rdt_hw_domain *hw_dom;
+	bool msr_param_init = false;
 	struct msr_param msr_param;
 	cpumask_var_t cpu_mask;
 	struct rdt_domain *d;
 	bool mba_sc;
+	u32 closid;
 	int i, cpu;
 
 	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
 		return -ENOMEM;
 
-	/* TODO: learn these two by looping the config */
-	msr_param.low = closid;
-	msr_param.high = msr_param.low + 1;
 	msr_param.res = r;
 
 	mba_sc = is_mba_sc(r);
@@ -220,9 +219,21 @@ static int update_domains(struct rdt_resource *r, int closid)
 				continue;
 
 			apply_config(hw_dom, cfg, cpu_mask, mba_sc);
+
+			closid = cfg->closid;
+			if (!msr_param_init) {
+				msr_param.low = closid;
+				msr_param.high = closid;
+				msr_param_init = true;
+			} else {
+				msr_param.low = min(msr_param.low, closid);
+				msr_param.high = max(msr_param.high, closid);
+			}
 		}
 	}
 
+	msr_param.high += 1;
+
 	/*
 	 * Avoid writing the control msr with control values when
 	 * MBA software controller is enabled
@@ -301,7 +312,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
 	}
 
 	for_each_alloc_enabled_rdt_resource(r) {
-		ret = update_domains(r, closid);
+		ret = update_domains(r);
 		if (ret)
 			goto out;
 	}
-- 
2.18.0