On Tue, 2020-12-01 at 16:45 -0800, Dexuan Cui wrote: > The commit f36a74b9345a itself is good, but it causes a panic in a > Linux VM that runs on a Hyper-V host that doesn't have the 15-bit > Extended APIC ID support: > kernel BUG at arch/x86/kernel/apic/io_apic.c:2408! > > This happens because the Hyper-V ioapic_ir_domain (which is defined in > drivers/iommu/hyperv-iommu.c) can not be found. Fix the panic by > properly claiming the only I/O APIC emulated by Hyper-V. > > Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> > Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > Fixes: f36a74b9345a ("x86/ioapic: Use I/O-APIC ID for finding irqdomain, not index") > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Oops, apologies for missing that. Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Amazon Development Centre (London) Ltd. Registered in England and Wales with registration number 04543232 with its registered office at 1 Principal Place, Worship Street, London EC2A 2FA, United Kingdom.