Messages in this thread | | | Subject | Re: [PATCH v5 14/18] kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode. | From | Suravee Suthikulpanit <> | Date | Fri, 21 Feb 2020 09:27:29 +0700 |
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Alex,
On 2/19/20 1:51 AM, Alex Williamson wrote: > On Thu, 14 Nov 2019 14:15:16 -0600 > Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> wrote: > >> AMD SVM AVIC accelerates EOI write and does not trap. This causes >> in-kernel PIT re-injection mode to fail since it relies on irq-ack >> notifier mechanism. So, APICv is activated only when in-kernel PIT >> is in discard mode e.g. w/ qemu option: >> >> -global kvm-pit.lost_tick_policy=discard >> >> Also, introduce APICV_INHIBIT_REASON_PIT_REINJ bit to be used for this >> reason. >> >> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> >> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> >> --- > > Hi, > > I've bisected https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.kernel.org%2Fshow_bug.cgi%3Fid%3D206579&data=02%7C01%7Csuravee.suthikulpanit%40amd.com%7C4d26019120374670e2ec08d7b4a39d9f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637176487135073269&sdata=Yp1ZSoOxVphXyd60gerlaJkOF67r65emQZ4zhc%2BLFy4%3D&reserved=0 (a > kernel NULL pointer deref when using device assigned on AMD platforms) > to this commit, e2ed4078a6ef3ddf4063329298852e24c36d46c8. My VM is a > very basic libvirt managed domain with an assigned NIC, I don't even > have an OS installed:
Thanks for the bisect information. I'm currently working on reproducing this issue. On your system are you enabling AVIC (e.g. modprobe kvm_amd avic=1)?
Suravee
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