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

[Deepak Gupta <debug@rivosinc.com>]

On Wed, Jun 05, 2024 at 01:56:47PM -0700, Samuel Holland wrote:
>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.
>
>Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
>---
>
> 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 1153b96346ae..bfe8550c0aae 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:
>@@ -725,12 +725,12 @@ 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 1319b29ce3b5..3e8ece31c30d 100644
>--- a/arch/riscv/kernel/smpboot.c
>+++ b/arch/riscv/kernel/smpboot.c
>@@ -231,8 +231,6 @@ asmlinkage __visible void smp_callin(void)
> 			elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
> 	}
>
>-	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.

Suggestion:
Squash with current patch 1 and call it patch 2.

>-- 
>2.44.1
>

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