He, Qing wrote: > Hi folks, > I found that Windows guests often fail reboots in current > kvm.git. Either the guest hangs, or it reports double fault exception > which causes qemu aborts. This is not shown with -no-kvm-irqchip option. > > After some investigation, it seems that this is caused by lack > of in-kernel components reset. Several windows guests will write RESET > command to 8042, the keyboard controller. On receiving the command, qemu > device model will call qemu_system_reset() to reset everything to the > initial state. However, this mechanism is broken when in-kernel > components is introduced: qemu doesn't communicate the reset request to > kvm, so kvm uses stale device state on the next booting, which fails > reboot. > > To resolve this, there are at least two options: > 1. modify qemu_system_reset(), so that qemu destroys kvm context > and re-creates. >
That's too destructive, there's lots of state to recreate, things like dirty page logging need to be reinitialized. > 2. introduce a new ioctl, say KVM_RESET, to kvm. On receiving > this ioctl, the kernel calls reset handlers registered by other > components (vcpu, lapic, pic, ioapic, pit, etc.), either against vm or > against each vcpu. > > There's a third option: let the regular qemu logic work, and after that copy the state to kvm (just like after vm restore). I tried that but there were problems so I dropped it. But the approach should work. > IMO, the first one is easier in modification and maintaining, > but the second one is closer to qemu logics. Which do you think is more > appropriate? > > I think #2. Synchronization will be difficult; we'll need to send signals to all other vcpus so that they drop the vcpu mutex. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
