Re: [PATCH 12/30] x86, kaiser: map GDT into user page tables

[Dave Hansen]

On 11/20/2017 12:22 PM, Thomas Gleixner wrote:
> On Fri, 10 Nov 2017, Dave Hansen wrote:
>>  	__set_fixmap(get_cpu_gdt_ro_index(cpu), get_cpu_gdt_paddr(cpu), prot);
>> +
>> +	/* CPU 0's mapping is done in kaiser_init() */
>> +	if (cpu) {
>> +		int ret;
>> +
>> +		ret = kaiser_add_mapping((unsigned long) get_cpu_gdt_ro(cpu),
>> +					 PAGE_SIZE, __PAGE_KERNEL_RO);
>> +		/*
>> +		 * We do not have a good way to fail CPU bringup.
>> +		 * Just WARN about it and hope we boot far enough
>> +		 * to get a good log out.
>> +		 */
> 
> The GDT fixmap can be set up before the CPU is started. There is no reason
> to do that in cpu_init().

Do you mean the __set_fixmap(), or my call to kaiser_add_mapping()?

Where would you suggest we move it?  Here seems kinda nice because it's
right next to where the get_cpu_gdt_ro() mapping is created.