Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] iommu/hyper-v: Fix panic on a host without the 15-bit APIC ID support | Date | Wed, 02 Dec 2020 10:56:23 +0100 |
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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
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