On 13/10/2020 14:16, Jan Beulich wrote:
> On 05.10.2020 14:23, Andrew Cooper wrote:
>> --- a/xen/arch/x86/smpboot.c
>> +++ b/xen/arch/x86/smpboot.c
>> @@ -971,16 +971,16 @@ static void cpu_smpboot_free(unsigned int cpu, bool
>> remove)
>> if ( IS_ENABLED(CONFIG_PV32) )
>> FREE_XENHEAP_PAGE(per_cpu(compat_gdt, cpu));
>>
>> + if ( stack_base[cpu] )
>> + memguard_unguard_stack(stack_base[cpu]);
>> +
>> if ( remove )
>> {
>> FREE_XENHEAP_PAGE(per_cpu(gdt, cpu));
>> FREE_XENHEAP_PAGE(idt_tables[cpu]);
>>
>> if ( stack_base[cpu] )
>> - {
>> - memguard_unguard_stack(stack_base[cpu]);
>> FREE_XENHEAP_PAGES(stack_base[cpu], STACK_ORDER);
>> - }
>> }
>> }
> In my initial reply to Marek's report I did suggest putting the fix
> in the alloc path in order to keep the pages "guarded" while the CPU
> is parked
In which case you should have identified that bug explicitly.
Because I can't read your mind while fixing the other real bugs in your
suggestion.
~Andrew
