On Wed, Sep 04, 2024, Nathan Chancellor wrote: > I bisected (log below) an issue with starting a nested guest that > appears on two of my newer Intel test machines (but not a somewhat old > laptop) when this change as commit 6f373f4d941b ("KVM: nVMX: Get > to-be-acknowledge IRQ for nested VM-Exit at injection site") in -next is > present in the host kernel. > > I start a virtual machine with a full distribution using QEMU then start > a nested virtual machine using QEMU with the same kernel and a much > simpler Buildroot initrd, just to test the ability to run a nested > guest. After this change, starting a nested guest results in no output > from the nested guest and eventually the first guest restarts, sometimes > printing a lockup message that appears to be caused from qemu-system-x86 *sigh* It's not you, it's me. I just bisected hangs in my nested setup to this same commit. Apparently, I completely and utterly failed at testing. There isn't that much going on here, so knock wood, getting a root cause shouldn't be terribly difficult.