id = 1008
title = "nested virtualisation with old host kernel, qemu 7.0.0 broken"
state = "opened"
created_at = "2022-04-30T11:31:10.634Z"
closed_at = "n/a"
labels = ["accel: KVM", "target: i386"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1008"
host-os = "n/a"
host-arch = "n/a"
qemu-version = "n/a"
guest-os = "n/a"
guest-arch = "n/a"
description = """```
$ qemu-system-x86_64 -enable-kvm -nographic
qemu-system-x86_64: error: failed to set MSR 0xc0000104 to 0x100000000
qemu-system-x86_64: ../target/i386/kvm/kvm.c:2996: kvm_buf_set_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.
Aborted (core dumped)

$
```"""
reproduce = """1. (hardware) Host 1 running kernel 5.10 with nested kvm enabled
2. (virtual) Host 2, with qemu 7.0.0 installed
3. In the inner/virtual host, run: `qemu-system-x86 -enable-kvm -nographic`"""
additional = """It is fixed by using either a more up-to-date kernel version on the hardware/outer host (5.17.x for example), or by reverting to qemu 6.2.0 in the virtual/inner host.

I have also reproduced this with latest qemu master, commit 731340813fdb4cb8339edb8630e3f923b7d987ec.

**Reverting commit 3e4546d5bd38a1e98d4bd2de48631abf0398a3a2 also fixes the issue.**"""