On 04/01/2010 10:35 PM, Wenhao Xu wrote:
Does current qemu-kvm (qemu v0.12.3) use the irqchip, pit of KVM? I
cannot find any KVM_CREATE_IRQCHIP and KVM_CREATE_PIT in the qemu
code.
Are you looking at qemu or qemu-kvm?
Concerning the interface between qemu and kvm, I have the following confusion:
1. How irqchip and pit of KVM collaborating with the irq and pit
emulation of QEMU? As far as I see, qemu-kvm still uses qemu's irq and
pit emulation, doesn't it?
No, they're completely separate.
2. For return from KVM to QEMU, I cannot get the meaning of two exit reasons:
case KVM_EXIT_EXCEPTION:
What exception will cause KVM exit?
I think that's obsolete.
default:
dprintf("kvm_arch_handle_exit\n");
ret = kvm_arch_handle_exit(env, run);
What exit reasons are default?
3. How could DMA interrupt the cpu when it finishes and the qemu-kvm
is still running in kvm now?
Usually the device that does the dma will raise an interrupt, which qemu
is waiting for.
I am still working in the patch, but these confusions really prevent
me moving forward. Thanks first for you guys giving me more hints.
The following is the code so far I write:
The main idea is synchronizing the CPU state and enter into the
emulator mode when switching from kvm to emulator. I only do the
switch when the exit reason is KVM_EXIT_IRQ_WINDOW_OPEN.
That doesn't happen with qemu-kvm.
However, I got the following errors:
Whenever switch from kvm to qemu, the interrupt request in qemu will
cause qemu enter into smm mode which is definitely a bug.
Definitely shouldn't happen.
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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