On 08.11.2021 10:36, Roger Pau Monné wrote: > On Mon, Nov 08, 2021 at 08:40:59AM +0100, Jan Beulich wrote: >> On 05.11.2021 16:38, Roger Pau Monné wrote: >>> On Fri, Nov 05, 2021 at 01:32:18PM +0100, Jan Beulich wrote: >>>> --- a/xen/arch/x86/setup.c >>>> +++ b/xen/arch/x86/setup.c >>>> @@ -1699,6 +1699,13 @@ void __init noreturn __start_xen(unsigne >>>> >>>> dmi_scan_machine(); >>>> >>>> + /* >>>> + * IOMMU-related ACPI table parsing has to happen before APIC >>>> probing, for >>>> + * check_x2apic_preenabled() to be able to observe respective >>>> findings, in >>>> + * particular iommu_intremap having got turned off. >>>> + */ >>>> + acpi_iommu_init(); >>> >>> If we pull this out I think we should add a check for acpi_disabled >>> and if set turn off iommu_intremap and iommu_enable? >> >> Hmm, I should have added a note regarding this. If we want to exactly >> retain prior behavior, acpi_ht would also need checking. Yet that has >> gone wrong long ago: We parse way too many tables when acpi_disabled >> && acpi_ht, and hence while correct wrt to prior behavior I'd consider >> it wrong to (re)add a "!acpi_ht" check. >> >> As a result I'm of the opinion that checking acpi_disabled here also >> isn't necessarily appropriate, and instead IOMMU disabling would >> better be solely under the control of "iommu=". > > I haven't looked very deeply, but will the acpi helpers work correctly > in that case? As acpi_boot_table_init will be short-circuited if > `acpi_disabled && !acpi_ht`.
Oh, that's a good point you make. Jan
