[PATCH v1 16/20] x86/resctrl: Move mbm_overflow_count() into resctrl_arch_rmid_read()

From: James Morse <james.morse@arm.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>,
	Reinette Chatre <reinette.chatre@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
	James Morse <james.morse@arm.com>,
	shameerali.kolothum.thodi@huawei.com,
	Jamie Iles <jamie@nuviainc.com>,
	D Scott Phillips OS <scott@os.amperecomputing.com>,
	lcherian@marvell.com, bobo.shaobowang@huawei.com
Subject: [PATCH v1 16/20] x86/resctrl: Move mbm_overflow_count() into resctrl_arch_rmid_read()
Date: Thu, 29 Jul 2021 22:36:06 +0000	[thread overview]
Message-ID: <20210729223610.29373-17-james.morse@arm.com> (raw)
In-Reply-To: <20210729223610.29373-1-james.morse@arm.com>

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. When reading a bandwidth
counter, mbm_overflow_count() must be used to correct for any possible
overflow.

mbm_overflow_count() is architecture specific, its behaviour should
be part of resctrl_arch_rmid_read().

Move the mbm_overflow_count() calls into resctrl_arch_rmid_read().
This allows the resctrl filesystems's prev_msr to be removed in
favour of the architecture private version.

Signed-off-by: James Morse <james.morse@arm.com>
---
 arch/x86/kernel/cpu/resctrl/internal.h |  2 --
 arch/x86/kernel/cpu/resctrl/monitor.c  | 42 ++++++++++++++------------
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index eca7793d3342..2d0a6bba4a01 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -280,7 +280,6 @@ struct rftype {
 /**
  * struct mbm_state - status for each MBM counter in each domain
  * @chunks:	Total data moved (multiply by rdt_group.mon_scale to get bytes)
- * @prev_msr:	Value of IA32_QM_CTR for this RMID last time we read it
  * @prev_bw_chunks: Previous chunks value read when for bandwidth calculation
  * @prev_bw:	The most recent bandwidth in MBps
  * @delta_bw:	Difference between the current and previous bandwidth
@@ -288,7 +287,6 @@ struct rftype {
  */
 struct mbm_state {
 	u64	chunks;
-	u64	prev_msr;
 	u64	prev_bw_chunks;
 	u32	prev_bw;
 	u32	delta_bw;
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index aa85cfd95904..39f7e74a4236 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -164,9 +164,20 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d,
 		memset(m, 0, sizeof(*m));
 }
 
+static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
+{
+	u64 shift = 64 - width, chunks;
+
+	chunks = (cur_msr << shift) - (prev_msr << shift);
+	return chunks >>= shift;
+}
+
 int resctrl_arch_rmid_read(struct rdt_resource	*r, struct rdt_domain *d,
 			   u32 rmid, enum resctrl_event_id eventid, u64 *val)
 {
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
+	struct arch_mbm_state *m;
 	u64 msr_val;
 
 	if (!cpumask_test_cpu(smp_processor_id(), &d->cpu_mask))
@@ -188,7 +199,13 @@ int resctrl_arch_rmid_read(struct rdt_resource	*r, struct rdt_domain *d,
 	if (msr_val & RMID_VAL_UNAVAIL)
 		return -EINVAL;
 
-	*val = msr_val;
+	m = get_arch_mbm_state(hw_dom, rmid, eventid);
+	if (m) {
+		*val = mbm_overflow_count(m->prev_msr, msr_val, hw_res->mbm_width);
+		m->prev_msr = msr_val;
+	} else {
+		*val = msr_val;
+	}
 
 	return 0;
 }
@@ -319,19 +336,10 @@ void free_rmid(u32 rmid)
 		list_add_tail(&entry->list, &rmid_free_lru);
 }
 
-static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
-{
-	u64 shift = 64 - width, chunks;
-
-	chunks = (cur_msr << shift) - (prev_msr << shift);
-	return chunks >>= shift;
-}
-
 static int __mon_event_count(u32 rmid, struct rmid_read *rr)
 {
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
 	struct mbm_state *m;
-	u64 chunks, tval = 0;
+	u64 tval = 0;
 
 	if (rr->first)
 		resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);
@@ -354,13 +362,11 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
 
 	if (rr->first) {
 		memset(m, 0, sizeof(struct mbm_state));
-		m->prev_bw_chunks = m->prev_msr = tval;
+		m->prev_bw_chunks = tval;
 		return 0;
 	}
 
-	chunks = mbm_overflow_count(m->prev_msr, tval, hw_res->mbm_width);
-	m->chunks += chunks;
-	m->prev_msr = tval;
+	m->chunks += tval;
 
 	rr->val += get_corrected_mbm_count(rmid, m->chunks);
 
@@ -375,14 +381,12 @@ static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
 	struct mbm_state *m = &rr->d->mbm_local[rmid];
-	u64 tval = 0, cur_bw, chunks, bw_chunks;
+	u64 tval = 0, cur_bw, bw_chunks;
 
 	if (resctrl_arch_rmid_read(rr->r, rr->d, rmid, rr->evtid, &tval))
 		return;
 
-	chunks = mbm_overflow_count(m->prev_msr, tval, hw_res->mbm_width);
-	m->chunks += chunks;
-	m->prev_msr = tval;
+	m->chunks += tval;
 	bw_chunks = get_corrected_mbm_count(rmid, m->chunks);
 
 	cur_bw = (bw_chunks - m->prev_bw_chunks) * hw_res->mon_scale;
-- 
2.30.2

