Message-ID: <ZdZPht8hY4J9uIOz@agluck-desk3>
Date: Wed, 21 Feb 2024 11:31:18 -0800
From: Tony Luck <tony.luck@...el.com>
To: "Chatre, Reinette" <reinette.chatre@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>, James Morse <james.morse@....com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
	Babu Moger <Babu.Moger@....com>,
	"shameerali.kolothum.thodi@...wei.com" <shameerali.kolothum.thodi@...wei.com>,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	"carl@...amperecomputing.com" <carl@...amperecomputing.com>,
	"lcherian@...vell.com" <lcherian@...vell.com>,
	"bobo.shaobowang@...wei.com" <bobo.shaobowang@...wei.com>,
	"tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>,
	"baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	"peternewman@...gle.com" <peternewman@...gle.com>,
	"dfustini@...libre.com" <dfustini@...libre.com>,
	"amitsinght@...vell.com" <amitsinght@...vell.com>,
	David Hildenbrand <david@...hat.com>
Subject: [PATCH v2] x86/resctrl: Fix WARN in get_domain_from_cpu()

reset_all_ctrls() and resctrl_arch_update_domains() use on_each_cpu_mask()
to call rdt_ctrl_update() on potentially one CPU from each domain.

But this means rdt_ctrl_update() needs to figure out which domain to
apply changes to. Doing so requires a search of all domains in a resource,
which can only be done safely if cpus_lock is held. Both callers do hold
this lock, but there isn't a way for a function called on another CPU
via IPI to verify this.

Fix by adding the target domain to the msr_param structure and passing an
array with CDP_NUM_TYPES entries. Then calling for each domain separately
using smp_call_function_single()

Change the low level cat_wrmsr(), mba_wrmsr_intel(), and mba_wrmsr_amd()
functions to just take a msr_param structure since it contains the
rdt_resource and rdt_domain information.

Signed-off-by: Tony Luck <tony.luck@...el.com>

---

Changes since v1:

* Avoid double IPI to the same core when CDP is enabled.
* Don't pass the resource and domain to functions that can
  get these from the msr_param structure.
* Clean up some fir tree issues in functions that I changed.


 arch/x86/kernel/cpu/resctrl/internal.h    |  4 +-
 arch/x86/kernel/cpu/resctrl/core.c        | 56 +++++++++------------
 arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 59 +++++++----------------
 arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 23 ++++-----
 4 files changed, 50 insertions(+), 92 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c99f26ebe7a6..2f21358b9621 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -383,6 +383,7 @@ static inline struct rdt_hw_domain *resctrl_to_arch_dom(struct rdt_domain *r)
  */
 struct msr_param {
 	struct rdt_resource	*res;
+	struct rdt_domain	*dom;
 	u32			low;
 	u32			high;
 };
@@ -442,8 +443,7 @@ struct rdt_hw_resource {
 	struct rdt_resource	r_resctrl;
 	u32			num_closid;
 	unsigned int		msr_base;
-	void (*msr_update)	(struct rdt_domain *d, struct msr_param *m,
-				 struct rdt_resource *r);
+	void			(*msr_update)(struct msr_param *m);
 	unsigned int		mon_scale;
 	unsigned int		mbm_width;
 	unsigned int		mbm_cfg_mask;
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 8a4ef4f5bddc..643bf64bf1be 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -56,14 +56,9 @@ int max_name_width, max_data_width;
  */
 bool rdt_alloc_capable;
 
-static void
-mba_wrmsr_intel(struct rdt_domain *d, struct msr_param *m,
-		struct rdt_resource *r);
-static void
-cat_wrmsr(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r);
-static void
-mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m,
-	      struct rdt_resource *r);
+static void mba_wrmsr_intel(struct msr_param *m);
+static void cat_wrmsr(struct msr_param *m);
+static void mba_wrmsr_amd(struct msr_param *m);
 
 #define domain_init(id) LIST_HEAD_INIT(rdt_resources_all[id].r_resctrl.domains)
 
@@ -309,12 +304,11 @@ static void rdt_get_cdp_l2_config(void)
 	rdt_get_cdp_config(RDT_RESOURCE_L2);
 }
 
-static void
-mba_wrmsr_amd(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
+static void mba_wrmsr_amd(struct msr_param *m)
 {
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(m->res);
+	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(m->dom);
 	unsigned int i;
-	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 
 	for (i = m->low; i < m->high; i++)
 		wrmsrl(hw_res->msr_base + i, hw_dom->ctrl_val[i]);
@@ -334,25 +328,22 @@ static u32 delay_bw_map(unsigned long bw, struct rdt_resource *r)
 	return r->default_ctrl;
 }
 
-static void
-mba_wrmsr_intel(struct rdt_domain *d, struct msr_param *m,
-		struct rdt_resource *r)
+static void mba_wrmsr_intel(struct msr_param *m)
 {
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(m->res);
+	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(m->dom);
 	unsigned int i;
-	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 
 	/*  Write the delay values for mba. */
 	for (i = m->low; i < m->high; i++)
-		wrmsrl(hw_res->msr_base + i, delay_bw_map(hw_dom->ctrl_val[i], r));
+		wrmsrl(hw_res->msr_base + i, delay_bw_map(hw_dom->ctrl_val[i], m->res));
 }
 
-static void
-cat_wrmsr(struct rdt_domain *d, struct msr_param *m, struct rdt_resource *r)
+static void cat_wrmsr(struct msr_param *m)
 {
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(m->res);
+	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(m->dom);
 	unsigned int i;
-	struct rdt_hw_domain *hw_dom = resctrl_to_arch_dom(d);
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 
 	for (i = m->low; i < m->high; i++)
 		wrmsrl(hw_res->msr_base + i, hw_dom->ctrl_val[i]);
@@ -387,19 +378,14 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r)
 
 void rdt_ctrl_update(void *arg)
 {
+	struct rdt_hw_resource *hw_res;
 	struct msr_param *m = arg;
-	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(m->res);
-	struct rdt_resource *r = m->res;
-	int cpu = smp_processor_id();
-	struct rdt_domain *d;
+	int t;
 
-	d = get_domain_from_cpu(cpu, r);
-	if (d) {
-		hw_res->msr_update(d, m, r);
-		return;
-	}
-	pr_warn_once("cpu %d not found in any domain for resource %s\n",
-		     cpu, r->name);
+	hw_res = resctrl_to_arch_res(m->res);
+	for (t = 0; t < CDP_NUM_TYPES; t++)
+		if (m[t].dom)
+			hw_res->msr_update(m + t);
 }
 
 /*
@@ -472,9 +458,11 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
 	hw_dom->ctrl_val = dc;
 	setup_default_ctrlval(r, dc);
 
+	m.res = r;
+	m.dom = d;
 	m.low = 0;
 	m.high = hw_res->num_closid;
-	hw_res->msr_update(d, &m, r);
+	hw_res->msr_update(&m);
 	return 0;
 }
 
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 7997b47743a2..09f6e624f1bb 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -272,22 +272,6 @@ static u32 get_config_index(u32 closid, enum resctrl_conf_type type)
 	}
 }
 
-static bool apply_config(struct rdt_hw_domain *hw_dom,
-			 struct resctrl_staged_config *cfg, u32 idx,
-			 cpumask_var_t cpu_mask)
-{
-	struct rdt_domain *dom = &hw_dom->d_resctrl;
-
-	if (cfg->new_ctrl != hw_dom->ctrl_val[idx]) {
-		cpumask_set_cpu(cpumask_any(&dom->cpu_mask), cpu_mask);
-		hw_dom->ctrl_val[idx] = cfg->new_ctrl;
-
-		return true;
-	}
-
-	return false;
-}
-
 int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
 			    u32 closid, enum resctrl_conf_type t, u32 cfg_val)
 {
@@ -304,59 +288,50 @@ int resctrl_arch_update_one(struct rdt_resource *r, struct rdt_domain *d,
 	msr_param.res = r;
 	msr_param.low = idx;
 	msr_param.high = idx + 1;
-	hw_res->msr_update(d, &msr_param, r);
+	hw_res->msr_update(&msr_param);
 
 	return 0;
 }
 
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid)
 {
+	struct msr_param msr_param[CDP_NUM_TYPES];
 	struct resctrl_staged_config *cfg;
 	struct rdt_hw_domain *hw_dom;
-	struct msr_param msr_param;
 	enum resctrl_conf_type t;
-	cpumask_var_t cpu_mask;
 	struct rdt_domain *d;
+	bool need_update;
+	int cpu;
 	u32 idx;
 
 	/* Walking r->domains, ensure it can't race with cpuhp */
 	lockdep_assert_cpus_held();
 
-	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
-		return -ENOMEM;
-
-	msr_param.res = NULL;
+	memset(msr_param, 0, sizeof(msr_param));
 	list_for_each_entry(d, &r->domains, list) {
 		hw_dom = resctrl_to_arch_dom(d);
+		need_update = false;
 		for (t = 0; t < CDP_NUM_TYPES; t++) {
 			cfg = &hw_dom->d_resctrl.staged_config[t];
 			if (!cfg->have_new_ctrl)
 				continue;
 
 			idx = get_config_index(closid, t);
-			if (!apply_config(hw_dom, cfg, idx, cpu_mask))
+			if (cfg->new_ctrl == hw_dom->ctrl_val[idx])
 				continue;
-
-			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);
-			}
+			hw_dom->ctrl_val[idx] = cfg->new_ctrl;
+			cpu = cpumask_any(&d->cpu_mask);
+
+			msr_param[t].low = idx;
+			msr_param[t].high = msr_param[t].low + 1;
+			msr_param[t].res = r;
+			msr_param[t].dom = d;
+			need_update = true;
 		}
+		if (need_update)
+			smp_call_function_single(cpu, rdt_ctrl_update, &msr_param, 1);
 	}
 
-	if (cpumask_empty(cpu_mask))
-		goto done;
-
-	/* Update resource control msr on all the CPUs. */
-	on_each_cpu_mask(cpu_mask, rdt_ctrl_update, &msr_param, 1);
-
-done:
-	free_cpumask_var(cpu_mask);
-
 	return 0;
 }
 
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 011e17efb1a6..5d9ff8883c60 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2811,21 +2811,19 @@ static int rdt_init_fs_context(struct fs_context *fc)
 static int reset_all_ctrls(struct rdt_resource *r)
 {
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+	struct msr_param msr_param[CDP_NUM_TYPES];
 	struct rdt_hw_domain *hw_dom;
-	struct msr_param msr_param;
-	cpumask_var_t cpu_mask;
 	struct rdt_domain *d;
+	int cpu;
 	int i;
 
 	/* Walking r->domains, ensure it can't race with cpuhp */
 	lockdep_assert_cpus_held();
 
-	if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL))
-		return -ENOMEM;
-
-	msr_param.res = r;
-	msr_param.low = 0;
-	msr_param.high = hw_res->num_closid;
+	memset(msr_param, 0, sizeof(msr_param));
+	msr_param[0].res = r;
+	msr_param[0].low = 0;
+	msr_param[0].high = hw_res->num_closid;
 
 	/*
 	 * Disable resource control for this resource by setting all
@@ -2834,17 +2832,14 @@ static int reset_all_ctrls(struct rdt_resource *r)
 	 */
 	list_for_each_entry(d, &r->domains, list) {
 		hw_dom = resctrl_to_arch_dom(d);
-		cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
+		cpu = cpumask_any(&d->cpu_mask);
 
 		for (i = 0; i < hw_res->num_closid; i++)
 			hw_dom->ctrl_val[i] = r->default_ctrl;
+		msr_param[0].dom = d;
+		smp_call_function_single(cpu, rdt_ctrl_update, &msr_param, 1);
 	}
 
-	/* Update CBM on all the CPUs in cpu_mask */
-	on_each_cpu_mask(cpu_mask, rdt_ctrl_update, &msr_param, 1);
-
-	free_cpumask_var(cpu_mask);
-
 	return 0;
 }
 
-- 
2.43.0

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