[PATCH] arm64: armv8_deprecated: Fix warning in isndep cpuhp starting process

[Will Deacon]

On Tue, Apr 23, 2024 at 05:35:01PM +0800, Wei Li wrote:
> The function run_all_insn_set_hw_mode() is registered as startup callback
> of 'CPUHP_AP_ARM64_ISNDEP_STARTING', it invokes set_hw_mode() methods of
> all emulated instructions.
> 
> As the STARTING callbacks are not expected to fail, if one of the
> set_hw_mode() fails, e.g. due to el0 mixed-endian is not supported for
> 'setend', it will report a warning:
> 
> ```
> CPU[2] cannot support the emulation of setend
> CPU 2 UP state arm64/isndep:starting (136) failed (-22)
> CPU2: Booted secondary processor 0x0000000002 [0x414fd0c1]
> ```
> 
> To fix it, add a check for INSN_UNAVAILABLE status and skip the process.
> 
> Signed-off-by: Wei Li <liwei391 at huawei.com>
> ---
>  arch/arm64/kernel/armv8_deprecated.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
> index dd6ce86d4332..b776e7424fe9 100644
> --- a/arch/arm64/kernel/armv8_deprecated.c
> +++ b/arch/arm64/kernel/armv8_deprecated.c
> @@ -462,6 +462,9 @@ static int run_all_insn_set_hw_mode(unsigned int cpu)
>  	for (int i = 0; i < ARRAY_SIZE(insn_emulations); i++) {
>  		struct insn_emulation *insn = insn_emulations[i];
>  		bool enable = READ_ONCE(insn->current_mode) == INSN_HW;
> +		if (insn->status == INSN_UNAVAILABLE)
> +			continue;
> +
>  		if (insn->set_hw_mode && insn->set_hw_mode(enable)) {
>  			pr_warn("CPU[%u] cannot support the emulation of %s",
>  				cpu, insn->name);

Isn't this part of the warning useful, though? ^^^

Will