linux-kernel - [PATCH 3/3] RISC-V: Fix non-smp kernel boot on SMP systems

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Message-Id: <1545865741-22795-4-git-send-email-atish.patra@wdc.com>
Date:   Wed, 26 Dec 2018 15:09:01 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-riscv@...ts.infradead.org
Cc:     Atish Patra <atish.patra@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Jason Cooper <jason@...edaemon.net>,
        linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Michael Clark <michaeljclark@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Patrick Stählin <me@...ki.ch>,
        Rob Herring <robh@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Damien Le Moal <Damien.LeMoal@....com>
Subject: [PATCH 3/3] RISC-V: Fix non-smp kernel boot on SMP systems

In non-smp configuration, hartid can be higher that NR_CPUS.
riscv_of_processor_hartid should not be compared to hartid to
NR_CPUS in that case. Moreover, this function checks all the
DT properties of a hart node. NR_CPUS comparison seems out of
place.

Do cpuid comparison with NR_CPUs in smp setup code. Update the
drivers to handle appropriate code as well.

Signed-off-by: Atish Patra <atish.patra@....com>
---
 arch/riscv/kernel/cpu.c           |  4 ----
 arch/riscv/kernel/smp.c           |  1 -
 arch/riscv/kernel/smpboot.c       |  5 +++++
 drivers/clocksource/riscv_timer.c | 21 ++++++++++++++++++---
 drivers/irqchip/irq-sifive-plic.c |  5 +++++
 5 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index b4a7d442..251ffab6 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -34,10 +34,6 @@ int riscv_of_processor_hartid(struct device_node *node)
 		pr_warn("Found CPU without hart ID\n");
 		return -(ENODEV);
 	}
-	if (hart >= NR_CPUS) {
-		pr_info("Found hart ID %d, which is above NR_CPUs.  Disabling this hart\n", hart);
-		return -(ENODEV);
-	}
 
 	if (of_property_read_string(node, "status", &status)) {
 		pr_warn("CPU with hartid=%d has no \"status\" property\n", hart);
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 57b1383e..9ea7ac7d 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -49,7 +49,6 @@ int riscv_hartid_to_cpuid(int hartid)
 			return i;
 
 	pr_err("Couldn't find cpu id for hartid [%d]\n", hartid);
-	BUG();
 	return i;
 }
 
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index bb8cd242..05291840 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -66,6 +66,11 @@ void __init setup_smp(void)
 			found_boot_cpu = 1;
 			continue;
 		}
+		if (cpuid >= NR_CPUS) {
+			pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
+				cpuid, hart);
+			break;
+		}
 
 		cpuid_to_hartid_map(cpuid) = hart;
 		set_cpu_possible(cpuid, true);
diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
index 084e97dc..acf2af10 100644
--- a/drivers/clocksource/riscv_timer.c
+++ b/drivers/clocksource/riscv_timer.c
@@ -89,20 +89,35 @@ static int __init riscv_timer_init_dt(struct device_node *n)
 	struct clocksource *cs;
 
 	hartid = riscv_of_processor_hartid(n);
+	if (hartid < 0) {
+		pr_warn("Not valid hartid for node [%pOF] error = [%d]\n",
+			n, hartid);
+		return hartid;
+	}
 	cpuid = riscv_hartid_to_cpuid(hartid);
 
+	if (cpuid < 0)
+		pr_warn("Invalid cpuid for hartid [%d]\n", hartid);
+
 	if (cpuid != smp_processor_id())
 		return 0;
 
+	pr_err("%s: Registering clocksource cpuid [%d] hartid [%d]\n",
+	       __func__, cpuid, hartid);
 	cs = per_cpu_ptr(&riscv_clocksource, cpuid);
-	clocksource_register_hz(cs, riscv_timebase);
+	error = clocksource_register_hz(cs, riscv_timebase);
 
+	if (error) {
+		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
+		       error, cpuid);
+		return error;
+	}
 	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
 			 "clockevents/riscv/timer:starting",
 			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
 	if (error)
-		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
-		       error, cpuid);
+		pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
+		       error);
 	return error;
 }
 
diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 357e9daf..254ecd76 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -237,6 +237,11 @@ static int __init plic_init(struct device_node *node,
 		}
 
 		cpu = riscv_hartid_to_cpuid(hartid);
+		if (cpu < 0) {
+			pr_warn("Invalid cpuid for context %d\n", i);
+			continue;
+		}
+
 		handler = per_cpu_ptr(&plic_handlers, cpu);
 		handler->present = true;
 		handler->ctxid = i;
-- 
2.7.4