linux-kernel - [v4 PATCH 2/8] RISC-V: Move cpuid to hartid mapping to SMP.

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Message-Id: <1549969812-22502-3-git-send-email-atish.patra@wdc.com>
Date:   Tue, 12 Feb 2019 03:10:06 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-riscv@...ts.infradead.org
Cc:     Atish Patra <atish.patra@....com>,
        Alan Kao <alankao@...estech.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andreas Schwab <schwab@...e.de>,
        Anup Patel <anup@...infault.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Jason Cooper <jason@...edaemon.net>,
        Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org,
        Marc Zyngier <marc.zyngier@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [v4 PATCH 2/8] RISC-V: Move cpuid to hartid mapping to SMP.

Currently, logical CPU id to physical hartid mapping is defined for both
smp and non-smp configurations. This is not required as we need this
only for smp configuration.  The mapping function can define directly
boot_cpu_hartid for non-smp use case.

The reverse mapping function i.e. hartid to cpuid can be called for any
valid but not booted harts. So it should return default cpu 0 only if it
is a boot hartid.

Signed-off-by: Atish Patra <atish.patra@....com>
Reviewed-by: Anup Patel <anup@...infault.org>
Reviewed-by: Christoph Hellwig <hch@....de>
---
 arch/riscv/include/asm/smp.h | 18 +++++++++++++-----
 arch/riscv/kernel/setup.c    |  9 ---------
 arch/riscv/kernel/smp.c      |  9 +++++++++
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index 41aa73b4..636a934f 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -19,16 +19,17 @@
 #include <linux/thread_info.h>
 
 #define INVALID_HARTID ULONG_MAX
+
+struct seq_file;
+extern unsigned long boot_cpu_hartid;
+
+#ifdef CONFIG_SMP
 /*
  * Mapping between linux logical cpu index and hartid.
  */
 extern unsigned long __cpuid_to_hartid_map[NR_CPUS];
 #define cpuid_to_hartid_map(cpu)    __cpuid_to_hartid_map[cpu]
 
-struct seq_file;
-
-#ifdef CONFIG_SMP
-
 /* print IPI stats */
 void show_ipi_stats(struct seq_file *p, int prec);
 
@@ -58,7 +59,14 @@ static inline void show_ipi_stats(struct seq_file *p, int prec)
 
 static inline int riscv_hartid_to_cpuid(int hartid)
 {
-	return 0;
+	if (hartid == boot_cpu_hartid)
+		return 0;
+
+	return -1;
+}
+static inline unsigned long cpuid_to_hartid_map(int cpu)
+{
+	return boot_cpu_hartid;
 }
 
 static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in,
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index fb09e013..61c81616 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -61,15 +61,6 @@ EXPORT_SYMBOL(empty_zero_page);
 atomic_t hart_lottery;
 unsigned long boot_cpu_hartid;
 
-unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
-	[0 ... NR_CPUS-1] = INVALID_HARTID
-};
-
-void __init smp_setup_processor_id(void)
-{
-	cpuid_to_hartid_map(0) = boot_cpu_hartid;
-}
-
 #ifdef CONFIG_BLK_DEV_INITRD
 static void __init setup_initrd(void)
 {
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 246635ea..b69883c6 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -36,6 +36,15 @@ enum ipi_message_type {
 	IPI_MAX
 };
 
+unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
+	[0 ... NR_CPUS-1] = INVALID_HARTID
+};
+
+void __init smp_setup_processor_id(void)
+{
+	cpuid_to_hartid_map(0) = boot_cpu_hartid;
+}
+
 /* A collection of single bit ipi messages.  */
 static struct {
 	unsigned long stats[IPI_MAX] ____cacheline_aligned;
-- 
2.7.4