linux-kernel - [PATCH v1 12/20] x86/recstrl: Add per-rmid arch private storage for overflow and chunks

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Message-Id: <20210729223610.29373-13-james.morse@arm.com>
Date:   Thu, 29 Jul 2021 22:36:02 +0000
From:   James Morse <james.morse@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Babu Moger <Babu.Moger@....com>,
        James Morse <james.morse@....com>,
        shameerali.kolothum.thodi@...wei.com,
        Jamie Iles <jamie@...iainc.com>,
        D Scott Phillips OS <scott@...amperecomputing.com>,
        lcherian@...vell.com, bobo.shaobowang@...wei.com
Subject: [PATCH v1 12/20] x86/recstrl: Add per-rmid arch private storage for overflow and chunks

resctrl_arch_rmid_read() is intended as the function that an
architecture agnostic resctrl filesystem driver can use to
read a value in bytes from a counter. Currently the function returns
the mbm values in chunks directly from hardware. For bandwidth
counters the resctrl filesystem provides the number of bytes
ever seen. Internally mba_sc uses a second prev_bw_msr to calculate
the bytes read since the last mba_sc invocation.

MPAM's scaling of counters can be changed at runtime, reducing the
resolution but increasing the range. When this is changed the prev_msr
values need to be converted by the architecture code.

Add storage for per-rmid private storage. The prev_msr and chunks
values will move here to allow resctrl_arch_rmid_read() to always
return the number of bytes read by this counter.

Signed-off-by: James Morse <james.morse@....com>
---
 arch/x86/kernel/cpu/resctrl/core.c     | 29 ++++++++++++++++++++++++++
 arch/x86/kernel/cpu/resctrl/internal.h | 13 ++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 8a3c13c6c19f..27c93d12ca27 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -432,6 +432,28 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
 	return 0;
 }
 
+static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_domain *hw_dom)
+{
+	size_t tsize;
+
+	if (is_mbm_total_enabled()) {
+		tsize = sizeof(*hw_dom->arch_mbm_total);
+		hw_dom->arch_mbm_total = kcalloc(num_rmid, tsize, GFP_KERNEL);
+		if (!hw_dom->arch_mbm_total)
+			return -ENOMEM;
+	}
+	if (is_mbm_local_enabled()) {
+		tsize = sizeof(*hw_dom->arch_mbm_local);
+		hw_dom->arch_mbm_local = kcalloc(num_rmid, tsize, GFP_KERNEL);
+		if (!hw_dom->arch_mbm_local) {
+			kfree(hw_dom->arch_mbm_total);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * domain_add_cpu - Add a cpu to a resource's domain list.
  *
@@ -481,6 +503,11 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
 		return;
 	}
 
+	if (r->mon_capable && arch_domain_mbm_alloc(r->num_rmid, hw_dom)) {
+		kfree(d);
+		return;
+	}
+
 	list_add_tail(&d->list, add_pos);
 
 	err = resctrl_online_domain(r, d);
@@ -516,6 +543,8 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
 			d->plr->d = NULL;
 
 		kfree(hw_dom->ctrl_val);
+		kfree(hw_dom->arch_mbm_total);
+		kfree(hw_dom->arch_mbm_local);
 		kfree(hw_dom);
 		return;
 	}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 0a5721e1cc07..aaae900a8ef3 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -303,17 +303,30 @@ struct mbm_state {
 	bool	delta_comp;
 };
 
+/**
+ * struct arch_mbm_state - values used to compute resctrl_arch_rmid_read()s
+ *			   return value.
+ * @prev_msr	Value of IA32_QM_CTR for this RMID last time we read it
+ */
+struct arch_mbm_state {
+	u64	prev_msr;
+};
+
 /**
  * struct rdt_hw_domain - Arch private attributes of a set of CPUs that share
  *			  a resource
  * @d_resctrl:	Properties exposed to the resctrl file system
  * @ctrl_val:	array of cache or mem ctrl values (indexed by CLOSID)
+ * @arch_mbm_total:	arch private state for MBM total bandwidth
+ * @arch_mbm_local:	arch private state for MBM local bandwidth
  *
  * Members of this structure are accessed via helpers that provide abstraction.
  */
 struct rdt_hw_domain {
 	struct rdt_domain		d_resctrl;
 	u32				*ctrl_val;
+	struct arch_mbm_state		*arch_mbm_total;
+	struct arch_mbm_state		*arch_mbm_local;
 };
 
 static inline struct rdt_hw_domain *resctrl_to_arch_dom(struct rdt_domain *r)
-- 
2.30.2