[PATCH v4 0/4] Miscellaneous kernel command line fixes

[PATCH v4 0/4] Miscellaneous kernel command line fixes

[Atish Patra]

Assorted command line option fixes for RISC-V.

Changes from v3->v4.
1. Fixed few checkpatch warnings.

Changes from v2->v3.
1. Merged patch 1 & 2 into one patch.

Changes from v1->v2.
1. Update pr_err string in patch (4/4) as per review.

Atish Patra (4):
RISC-V: Add RISC-V specific arch_match_cpu_phys_id
RISC-V: Implement nosmp commandline option.
RISC-V: Support nr_cpus command line option.
RISC-V: Fix minor checkpatch issues.

arch/riscv/kernel/cpu.c     |  3 +--
arch/riscv/kernel/smp.c     |  8 +++++++-
arch/riscv/kernel/smpboot.  |  0
arch/riscv/kernel/smpboot.c | 22 ++++++++++++++++++++--
4 files changed, 28 insertions(+), 5 deletions(-)
create mode 100644 arch/riscv/kernel/smpboot.

--
2.21.0

[PATCH 1/4] RISC-V: Add RISC-V specific arch_match_cpu_phys_id

[Atish Patra]

OF/DT core has a hook for architecture specific logical cpuid to hartid
mapping. By implementing this, we can pass the logical cpu id to cpu
node parsing functions.

Fix the instances where logical cpuid is expected as an argument in
of_get_cpu_node.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
---
 arch/riscv/kernel/cpu.c | 3 +--
 arch/riscv/kernel/smp.c | 6 ++++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index cf2fca12414a..c8d2a3223099 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -136,8 +136,7 @@ static void c_stop(struct seq_file *m, void *v)
 static int c_show(struct seq_file *m, void *v)
 {
 	unsigned long cpu_id = (unsigned long)v - 1;
-	struct device_node *node = of_get_cpu_node(cpuid_to_hartid_map(cpu_id),
-						   NULL);
+	struct device_node *node = of_get_cpu_node(cpu_id, NULL);
 	const char *compat, *isa, *mmu;
 
 	seq_printf(m, "processor\t: %lu\n", cpu_id);
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 0c41d07ec281..89251f8ab754 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -70,6 +70,12 @@ void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out)
 	for_each_cpu(cpu, in)
 		cpumask_set_cpu(cpuid_to_hartid_map(cpu), out);
 }
+
+bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
+{
+	return phys_id == cpuid_to_hartid_map(cpu);
+}
+
 /* Unsupported */
 int setup_profiling_timer(unsigned int multiplier)
 {
-- 
2.21.0

[PATCH 2/4] RISC-V: Implement nosmp commandline option.

[Atish Patra]

nosmp command line option sets max_cpus to zero. No secondary harts
will boot if this is enabled. But present cpu mask will still point to
all possible masks.

Fix present cpu mask for nosmp usecase.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/kernel/smpboot.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index eb533b5c2c8c..a8ad200581aa 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -47,6 +47,17 @@ void __init smp_prepare_boot_cpu(void)
 
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+	int cpuid;
+
+	/* This covers non-smp usecase mandated by "nosmp" option */
+	if (max_cpus == 0)
+		return;
+
+	for_each_possible_cpu(cpuid) {
+		if (cpuid == smp_processor_id())
+			continue;
+		set_cpu_present(cpuid, true);
+	}
 }
 
 void __init setup_smp(void)
@@ -74,7 +85,6 @@ void __init setup_smp(void)
 
 		cpuid_to_hartid_map(cpuid) = hart;
 		set_cpu_possible(cpuid, true);
-		set_cpu_present(cpuid, true);
 		cpuid++;
 	}
 
-- 
2.21.0

[PATCH 3/4] RISC-V: Support nr_cpus command line option.

[Atish Patra]

If nr_cpus command line option is set, maximum possible cpu should be
set to that value.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/kernel/smpboot.  |  0
 arch/riscv/kernel/smpboot.c | 10 +++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kernel/smpboot.

diff --git a/arch/riscv/kernel/smpboot. b/arch/riscv/kernel/smpboot.
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index a8ad200581aa..7a0b62252524 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -84,11 +84,19 @@ void __init setup_smp(void)
 		}
 
 		cpuid_to_hartid_map(cpuid) = hart;
-		set_cpu_possible(cpuid, true);
 		cpuid++;
 	}
 
 	BUG_ON(!found_boot_cpu);
+
+	if (cpuid > nr_cpu_ids)
+		pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
+			cpuid, nr_cpu_ids);
+
+	for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
+		if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID)
+			set_cpu_possible(cpuid, true);
+	}
 }
 
 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
-- 
2.21.0

[PATCH 4/4] RISC-V: Fix minor checkpatch issues.

[Atish Patra]

While working on the patches, I found some minor checkpatch issues.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/kernel/smp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 89251f8ab754..0115db1368a4 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -42,7 +42,7 @@ unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
 
 void __init smp_setup_processor_id(void)
 {
-       cpuid_to_hartid_map(0) = boot_cpu_hartid;
+	cpuid_to_hartid_map(0) = boot_cpu_hartid;
 }
 
 /* A collection of single bit ipi messages.  */
@@ -53,7 +53,7 @@ static struct {
 
 int riscv_hartid_to_cpuid(int hartid)
 {
-	int i = -1;
+	int i;
 
 	for (i = 0; i < NR_CPUS; i++)
 		if (cpuid_to_hartid_map(i) == hartid)
-- 
2.21.0

Re: [PATCH 4/4] RISC-V: Fix minor checkpatch issues.

[Christoph Hellwig]

On Wed, Apr 24, 2019 at 02:48:01PM -0700, Atish Patra wrote:
> While working on the patches, I found some minor checkpatch issues.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 2/4] RISC-V: Implement nosmp commandline option.

[Sudeep Holla]

On Wed, Apr 24, 2019 at 02:47:59PM -0700, Atish Patra wrote:
> nosmp command line option sets max_cpus to zero. No secondary harts
> will boot if this is enabled. But present cpu mask will still point to
> all possible masks.
>
> Fix present cpu mask for nosmp usecase.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

I just noticed RISC-V has CONFIG_SMP option configurable. ARM64 has
it always on and no option to disable :)

Anyways, this looks good.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

--
Regards,
Sudeep

Re: [PATCH 3/4] RISC-V: Support nr_cpus command line option.

[Sudeep Holla]

On Wed, Apr 24, 2019 at 02:48:00PM -0700, Atish Patra wrote:
> If nr_cpus command line option is set, maximum possible cpu should be
> set to that value.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

FWIW,

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>

--
Regards,
Sudeep