[PATCH v8] um: Enable preemption in UML

[Anton Ivanov]

On 01/04/2024 12:04, Tiwei Bie wrote:
> On 3/29/24 3:50 AM, anton.ivanov at cambridgegreys.com wrote:
> [...]
>> +
>> +void kernel_fpu_begin(void)
>> +{
>> +	preempt_disable();
>> +
>> +	WARN_ON(this_cpu_read(in_kernel_fpu));
>> +
>> +	this_cpu_write(in_kernel_fpu, true);
>> +
>> +#ifdef CONFIG_64BIT
>> +	if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT)))
>> +		__builtin_ia32_xsaveopt64(&current_thread_info()->aux_fp_regs, KNOWN_387_FEATURES);
>> +	else if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE)))
>> +			__builtin_ia32_xsave64(&current_thread_info()->aux_fp_regs, KNOWN_387_FEATURES);
> 
> Only need two levels of indentation (i.e. two tabs) here.
> 
>> +	else
>> +		__builtin_ia32_fxsave64(&current_thread_info()->aux_fp_regs);
>> +#else
>> +	if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT)))
>> +		__builtin_ia32_xsaveopt(&current->aux_fp_regs, KNOWN_387_FEATURES);
>> +	else if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE)))
>> +			__builtin_ia32_xsave(&current->aux_fp_regs, KNOWN_387_FEATURES);
> 
> Ditto.
> 
>> +	else
>> +		__builtin_ia32_fxsave(&current->aux_fp_regs);
>> +#endif
>> +}
>> +EXPORT_SYMBOL_GPL(kernel_fpu_begin);
>> +
> [...]
>>   
>> @@ -466,6 +475,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
>>   
>>   	address &= PAGE_MASK;
>>   
>> +	preempt_disable();
>> +
>>   	pgd = pgd_offset(mm, address);
>>   	if (!pgd_present(*pgd))
>>   		goto kill;
>> @@ -520,6 +531,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
>>   
>>   	*pte = pte_mkuptodate(*pte);
>>   
>> +	preempt_enable();
>>   	return;
>>   
>>   kill:
> 
> Preemption isn't enabled in the error path.

Thanks - missed that.

> 
> Regards,
> Tiwei
> 

-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/