linux-kernel - Virtual LAPIC page corruption

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Message-ID: <67D1E884-FE2C-44C3-8214-75958A9D445A@nutanix.com>
Date:   Wed, 13 May 2020 04:21:12 +0000
From:   Suresh Gumpula <suresh.gumpula@...anix.com>
To:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Virtual LAPIC page corruption

Hi,

We are a seeing a problem with windows guests(2016/2012R2) where guest crashes with 
Virtual APIC page corruption similar to the following redhat ticket.
https://bugzilla.redhat.com/show_bug.cgi?id=1751017

> Arg4: 0000000000000017, Type of corrupted region, can be
	16  : Critical floating point control register modification
	17  : Local APIC modification

Here, we are seeing the corruption LAPIC page and guest is BSOD'ing.
Looking at the guest windows dump, we see the full page is zeroed. And it seems the 
Guest windows kernel patchguard is detecting this case and resetting the VM.

Is it possible that KVM, somehow corrupted the virtual LAPIC page?  While the guest is running
the KVM is not supposed to touch that vcpu lapic page?

Could you please give us some pointers on what could wrong here. Is it a known issue in the kvm?
We are using the host kernel 4.19 and qemu 2.12 and windows guests(2016/2012)

Thanks,
Suresh