[PATCH v2 3/3] riscv: Call riscv_user_isa_enable() only on the boot hart

From: Samuel Holland
Date: Thu Jun 13 2024 - 13:15:34 EST


Now that the [ms]envcfg CSR value is maintained per thread, not per
hart, riscv_user_isa_enable() only needs to be called once during boot,
to set the value for the init task. This also allows it to be marked as
__init. riscv_isa_extension_check() sets any_cpu_has_zicboz, so it also
needs to be marked __init; it could have had this annotation already.

Reviewed-by: Deepak Gupta <debug@xxxxxxxxxxxx>
Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
---

Changes in v2:
- Rebase on riscv/linux.git for-next

arch/riscv/include/asm/cpufeature.h | 2 +-
arch/riscv/kernel/cpufeature.c | 8 ++++----
arch/riscv/kernel/smpboot.c | 2 --
3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index 347805446151..4bf7b7ebf6b3 100644
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -31,7 +31,7 @@ DECLARE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
/* Per-cpu ISA extensions. */
extern struct riscv_isainfo hart_isa[NR_CPUS];

-void riscv_user_isa_enable(void);
+void __init riscv_user_isa_enable(void);

#if defined(CONFIG_RISCV_MISALIGNED)
bool check_unaligned_access_emulated_all_cpus(void);
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index b5b8773c57e8..d3e3a865b874 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -27,7 +27,7 @@

#define NUM_ALPHA_EXTS ('z' - 'a' + 1)

-static bool any_cpu_has_zicboz;
+static bool any_cpu_has_zicboz __initdata;

unsigned long elf_hwcap __read_mostly;

@@ -74,7 +74,7 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned i
}
EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);

-static bool riscv_isa_extension_check(int id)
+static bool __init riscv_isa_extension_check(int id)
{
switch (id) {
case RISCV_ISA_EXT_ZICBOM:
@@ -769,12 +769,12 @@ unsigned long riscv_get_elf_hwcap(void)
return hwcap;
}

-void riscv_user_isa_enable(void)
+void __init riscv_user_isa_enable(void)
{
if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICBOZ))
current->thread.envcfg |= ENVCFG_CBZE;
else if (any_cpu_has_zicboz)
- pr_warn_once("Zicboz disabled as it is unavailable on some harts\n");
+ pr_warn("Zicboz disabled as it is unavailable on some harts\n");
}

#ifdef CONFIG_RISCV_ALTERNATIVE
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 19baf0d574d3..0646f79e0a02 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -235,8 +235,6 @@ asmlinkage __visible void smp_callin(void)
numa_add_cpu(curr_cpuid);
set_cpu_online(curr_cpuid, true);

- riscv_user_isa_enable();
-
/*
* Remote cache and TLB flushes are ignored while the CPU is offline,
* so flush them both right now just in case.
--
2.44.1