From: Luqman <1908489@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1908489] Re: qemu 4.2 bootloops with -cpu host and nested hypervisor
Date: Thu, 17 Dec 2020 09:15:06 -0000 [thread overview]
Message-ID: <160819650721.3633.7137990688169103960.malone@gac.canonical.com> (raw)
In-Reply-To: 160818582988.15420.16250079431178848252.malonedeb@soybean.canonical.com
** Attachment added: "vmxcap"
https://bugs.launchpad.net/qemu/+bug/1908489/+attachment/5444455/+files/vmxcap.txt
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https://bugs.launchpad.net/bugs/1908489
Title:
qemu 4.2 bootloops with -cpu host and nested hypervisor
Status in QEMU:
New
Bug description:
I've noticed that after upgrading from Ubuntu 18.04 to 20.04 that
nested virtualization isn't working anymore.
I have a simple repro where I create a Windows 10 2004 guest and
enable Hyper-V in it. This worked fine in 18.04 and specifically qemu
<4.2 (I specifically tested Qemu 2.11-4.1 which work fine).
The -cpu arg I'm passing is simply:
-cpu host,l3-cache=on,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time
Using that Windows won't boot because the nested hypervisor (Hyper-V)
is unable to be initialize and so it just boot loops. Using the exact
same qemu command works fine with 4.1 and lower.
Switching to a named CPU model like Skylake-Client-noTSX-IBRS instead
of host lets the VM boot but causes some weird behaviour later trying
to use nested VMs.
If I had to guess I think it would probably be related to this change
https://github.com/qemu/qemu/commit/20a78b02d31534ae478779c2f2816c273601e869
which would line up with 4.2 being the first bad version but unsure.
For now I just have to keep an older build of QEMU to work around
this. Let me know if there's anything else needed. I can also try out
any patches. I already have at least a dozen copies of qemu lying
around now.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1908489/+subscriptions
next prev parent reply other threads:[~2020-12-17 9:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 6:17 [Bug 1908489] [NEW] qemu 4.2 bootloops with -cpu host and nested hypervisor Luqman
2020-12-17 9:15 ` Luqman [this message]
2020-12-17 9:15 ` [Bug 1908489] " Luqman
2020-12-19 2:39 ` Luqman
2020-12-20 10:36 ` Luqman
2020-12-20 13:07 ` Paolo Bonzini
2020-12-20 13:07 ` Luqman
2020-12-20 13:58 ` Luqman
2020-12-20 14:50 ` Luqman
2020-12-20 15:00 ` Paolo Bonzini
2020-12-20 15:40 ` Luqman
2020-12-20 16:03 ` Paolo Bonzini
2020-12-20 16:10 ` Luqman
2020-12-23 7:42 ` Amdnative
2021-05-10 18:52 ` Thomas Huth
2021-08-18 13:21 ` Thomas Huth
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