From 33606b41d35115f887ea688b1a16f2ff85bf2fe4 Mon Sep 17 00:00:00 2001 From: Christian Krinitsin Date: Mon, 30 Jun 2025 12:24:58 +0000 Subject: add launchpad bug reports without comments --- results/scraper/launchpad-without-comments/1908489 | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 results/scraper/launchpad-without-comments/1908489 (limited to 'results/scraper/launchpad-without-comments/1908489') diff --git a/results/scraper/launchpad-without-comments/1908489 b/results/scraper/launchpad-without-comments/1908489 new file mode 100644 index 00000000..1e0ed728 --- /dev/null +++ b/results/scraper/launchpad-without-comments/1908489 @@ -0,0 +1,16 @@ +qemu 4.2 bootloops with -cpu host and nested hypervisor + +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. \ No newline at end of file -- cgit 1.4.1