> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Sent: Wednesday, December 2, 2020 1:56 AM > > On Tue, Dec 01 2020 at 16:45, 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 has nothing to do with the 15bit APIC ID support, really. > > The point is that the select() function only matches when I/O APIC ID is > 0, which is not guaranteed. That's independent of the 15bit extended > APIC ID feature. But the I/O-APIC ID is irrelevant on hyperv because > there is only one. > > > 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. > > We don't fix a panic. We fix a bug in the code :) > > I'll amend the changelog. > > Thanks, > > tglx Thank you for reworking the commit log, tglx! Dexuan
