RE: [PATCH V5 0/3] x86/Hyper-V/IOMMU: Add Hyper-V IOMMU driver to support x2apic mode

[Michael Kelley]

From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> Sent: Friday, February 22, 2019 4:12 AM
> 
> On the bare metal, enabling X2APIC mode requires interrupt remapping
> function which helps to deliver irq to cpu with 32-bit APIC ID.
> Hyper-V doesn't provide interrupt remapping function so far and Hyper-V
> MSI protocol already supports to deliver interrupt to the CPU whose
> virtual processor index is more than 255. IO-APIC interrupt still has
> 8-bit APIC ID limitation.
> 
> This patchset is to add Hyper-V stub IOMMU driver in order to enable
> X2APIC mode successfully in Hyper-V Linux guest. The driver returns X2APIC
> interrupt remapping capability when X2APIC mode is available. X2APIC
> destination mode is set to physical by PATCH 1 when X2APIC is available.
> Hyper-V IOMMU driver will scan cpu 0~255 and set cpu into IO-APIC MAX cpu
> affinity cpumask if its APIC ID is 8-bit. Driver creates a Hyper-V irq domain
> to limit IO-APIC interrupts' affinity and make sure cpus assigned with IO-APIC
> interrupt are in the scope of IO-APIC MAX cpu affinity.
> 
> Lan Tianyu (3):
>   x86/Hyper-V: Set x2apic destination mode to physical when x2apic is
>      available
>   HYPERV/IOMMU: Add Hyper-V stub IOMMU driver
>   MAINTAINERS: Add Hyper-V IOMMU driver into Hyper-V CORE AND DRIVERS
>     scope
> 

Joerg -- What's your take on this patch set now that it has settled down?  If
you are good with it, from the Microsoft standpoint we're hoping that it
can get into linux-next this week (given the extra week due to 5.0-rc8).

Thanks,

Michael Kelley