Re: [PATCH v2.1 1/6][4.16?] x86/x2APIC: defer probe until after IOMMU ACPI table parsing

[Jan Beulich <jbeulich@xxxxxxxx>]

On 08.11.2021 12:54, Roger Pau Monné wrote:
> On Mon, Nov 08, 2021 at 12:40:59PM +0100, Jan Beulich wrote:
>> While commit 46c4061cd2bf ("x86/IOMMU: mark IOMMU / intremap not in use
>> when ACPI tables are missing") deals with apic_x2apic_probe() as called
>> from x2apic_bsp_setup(), the check_x2apic_preenabled() path is similarly
>> affected: The call needs to occur after acpi_iommu_init(), such that
>> iommu_intremap getting disabled there can be properly taken into account
>> by apic_x2apic_probe().
>>
>> Note that, for the time being (further cleanup patches following),
>> reversing the order of the calls to generic_apic_probe() and
>> acpi_boot_init() is not an option:
>> - acpi_process_madt() calls clustered_apic_check() and hence relies on
>>   genapic to have got filled before,
>> - generic_bigsmp_probe() (called from acpi_process_madt()) needs to
>>   occur after generic_apic_probe(),
>> - acpi_parse_madt() (called from acpi_process_madt()) calls
>>   acpi_madt_oem_check(), which wants to be after generic_apic_probe().
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, but testing again revealed a problem, this time on AMD. The
dependencies are yet more complicated, so it'll need to be a mix of
v1 and v2: acpi_iommu_init() needs to be split out, but
generic_apic_probe() also needs to move. That's because
_pci_hide_device() relies on dom_xen to have got set up before.
Expect v2.2 after I have actually tested the outlined change.

Jan