Re: [PATCH 2/4] x86/ACPI: fix S3 wakeup vector mapping

[Jan Beulich <jbeulich@xxxxxxxx>]

On 23.11.2020 16:24, Roger Pau Monné wrote:
> On Mon, Nov 23, 2020 at 01:40:12PM +0100, Jan Beulich wrote:
>> --- a/xen/arch/x86/acpi/power.c
>> +++ b/xen/arch/x86/acpi/power.c
>> @@ -174,17 +174,20 @@ static void acpi_sleep_prepare(u32 state
>>      if ( state != ACPI_STATE_S3 )
>>          return;
>>  
>> -    wakeup_vector_va = __acpi_map_table(
>> -        acpi_sinfo.wakeup_vector, sizeof(uint64_t));
>> -
>>      /* TBoot will set resume vector itself (when it is safe to do so). */
>>      if ( tboot_in_measured_env() )
>>          return;
>>  
>> +    set_fixmap(FIX_ACPI_END, acpi_sinfo.wakeup_vector);
>> +    wakeup_vector_va = fix_to_virt(FIX_ACPI_END) +
>> +                       PAGE_OFFSET(acpi_sinfo.wakeup_vector);
>> +
>>      if ( acpi_sinfo.vector_width == 32 )
>>          *(uint32_t *)wakeup_vector_va = bootsym_phys(wakeup_start);
>>      else
>>          *(uint64_t *)wakeup_vector_va = bootsym_phys(wakeup_start);
>> +
>> +    clear_fixmap(FIX_ACPI_END);
> 
> Why not use vmap here instead of the fixmap?

Considering the S3 path is relatively fragile (as in: we end up
breaking it more often than about anything else) I wanted to
make as little of a change as possible. Hence I decided to stick
to the fixmap use that was (indirectly) used before as well.

Jan