Merge patch series "riscv: Unaligned access speed probing fixes and skipping"

Andrew Jones <ajones@ventanamicro.com> says:

The first six patches of this series are fixes and cleanups of the
unaligned access speed probing code. The next patch introduces a
kernel command line option that allows the probing to be skipped.
This command line option is a different approach than Jesse's [1].
[1] takes a cpu-list for a particular speed, supporting heterogeneous
platforms. With this approach, the kernel command line should only
be used for homogeneous platforms. [1] also only allowed 'fast' and
'slow' to be selected. This parameter also supports 'unsupported',
which could be useful for testing code paths gated on that. The final
patch adds the documentation.

[1] https://lore.kernel.org/linux-riscv/20240805173816.3722002-1-jesse@rivosinc.com/

* patches from https://lore.kernel.org/r/20250304120014.143628-10-ajones@ventanamicro.com:
  Documentation/kernel-parameters: Add riscv unaligned speed parameters
  riscv: Add parameter for skipping access speed tests
  riscv: Fix set up of vector cpu hotplug callback
  riscv: Fix set up of cpu hotplug callbacks
  riscv: Change check_unaligned_access_speed_all_cpus to void
  riscv: Fix check_unaligned_access_all_cpus
  riscv: Fix riscv_online_cpu_vec
  riscv: Annotate unaligned access init functions

Link: https://lore.kernel.org/r/20250304120014.143628-10-ajones@ventanamicro.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Author: Alexandre Ghiti

Documentation/admin-guide/kernel-parameters.txt

@@ -7477,6 +7477,22 @@
 			Note that genuine overcurrent events won't be
 			reported either.
 
+	unaligned_scalar_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping scalar unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same scalar unaligned access speed.
+
+	unaligned_vector_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping vector unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same vector unaligned access speed.
+
 	unknown_nmi_panic
 			[X86] Cause panic on unknown NMI.
 

arch/riscv/include/asm/cpufeature.h

@@ -63,7 +63,7 @@ void __init riscv_user_isa_enable(void);
 #define __RISCV_ISA_EXT_SUPERSET_VALIDATE(_name, _id, _sub_exts, _validate) \
 	_RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts), _validate)
 
-bool check_unaligned_access_emulated_all_cpus(void);
+bool __init check_unaligned_access_emulated_all_cpus(void);
 #if defined(CONFIG_RISCV_SCALAR_MISALIGNED)
 void check_unaligned_access_emulated(struct work_struct *work __always_unused);
 void unaligned_emulation_finish(void);
@@ -76,7 +76,7 @@ static inline bool unaligned_ctl_available(void)
 }
 #endif
 
-bool check_vector_unaligned_access_emulated_all_cpus(void);
+bool __init check_vector_unaligned_access_emulated_all_cpus(void);
 #if defined(CONFIG_RISCV_VECTOR_MISALIGNED)
 void check_vector_unaligned_access_emulated(struct work_struct *work __always_unused);
 DECLARE_PER_CPU(long, vector_misaligned_access);

arch/riscv/kernel/traps_misaligned.c

@@ -605,16 +605,10 @@ void check_vector_unaligned_access_emulated(struct work_struct *work __always_un
 	kernel_vector_end();
 }
 
-bool check_vector_unaligned_access_emulated_all_cpus(void)
+bool __init check_vector_unaligned_access_emulated_all_cpus(void)
 {
 	int cpu;
 
-	if (!has_vector()) {
-		for_each_online_cpu(cpu)
-			per_cpu(vector_misaligned_access, cpu) = RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED;
-		return false;
-	}
-
 	schedule_on_each_cpu(check_vector_unaligned_access_emulated);
 
 	for_each_online_cpu(cpu)
@@ -625,7 +619,7 @@ bool check_vector_unaligned_access_emulated_all_cpus(void)
 	return true;
 }
 #else
-bool check_vector_unaligned_access_emulated_all_cpus(void)
+bool __init check_vector_unaligned_access_emulated_all_cpus(void)
 {
 	return false;
 }
@@ -659,7 +653,7 @@ void check_unaligned_access_emulated(struct work_struct *work __always_unused)
 	}
 }
 
-bool check_unaligned_access_emulated_all_cpus(void)
+bool __init check_unaligned_access_emulated_all_cpus(void)
 {
 	int cpu;
 
@@ -684,7 +678,7 @@ bool unaligned_ctl_available(void)
 	return unaligned_ctl;
 }
 #else
-bool check_unaligned_access_emulated_all_cpus(void)
+bool __init check_unaligned_access_emulated_all_cpus(void)
 {
 	return false;
 }