From: tianyu....@microsoft.com <tianyu....@microsoft.com> 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 patch 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. Otherwise, > it creates a Hyper-V irq domain to limit IO-APIC interrupts' affinity > and make sure cpus assigned with IO-APIC interrupt have 8-bit APIC ID. > > Define 24 IO-APIC remapping entries because Hyper-V only expose one > single IO-APIC and one IO-APIC has 24 pins according IO-APIC spec( > https://pdos.csail.mit.edu/6.828/2016/readings/ia32/ioapic.pdf). > > Signed-off-by: Lan Tianyu <tianyu....@microsoft.com> > --- > Change since v4: > - Fix the loop of scan cpu's APIC id > > Change since v3: > - Make Hyper-V IOMMU as Hyper-V default driver > - Fix hypervisor_is_type() input parameter > - Check possible cpu numbers during scan 0~255 cpu's apic id. > > Change since v2: > - Improve comment about why save IO-APIC entry in the irq chip data. > - Some code improvement. > - Improve statement in the IOMMU Kconfig. > > Change since v1: > - Remove unused pr_fmt > - Make ioapic_ir_domain as static variable > - Remove unused variables cfg and entry in the > hyperv_irq_remapping_alloc() > - Fix comments
Reviewed-by: Michael Kelley <mikel...@microsoft.com>
