Re: [PATCH v4 0/6] Nonatomic interrupt injection

Avi Kivity
2010-09-16T13:35:23Z

On 08/30/2010 02:36 PM, Avi Kivity wrote:
> This patchset changes interrupt injection to be done from normal process
> context instead of interrupts disabled context. This is useful for real
> mode interrupt injection on Intel without the current hacks (injecting as
> a software interrupt of a vm86 task), reducing latencies, and later, for
> allowing nested virtualization code to use kvm_read_guest()/kvm_write_guest()
> instead of kmap() to access the guest vmcb/vmcs.
>
> Seems to survive a hack that cancels every 16th entry, after injection has
> already taken place.
>
> With the PIC reset fix posted earlier, this passes autotest on both AMD and
> Intel, with in-kernel irqchip. I'll run -no-kvm-irqchip tests shortly.
>
> Please review carefully, esp. the first patch. Any missing kvm_make_request()
> there may result in a hung guest.
>

This is now merged, with the change pointed out by Marcelo. Windows XP
x64 fails installation without

(vmx.c handle_cr())
case 8: {
u8 cr8_prev = kvm_get_cr8(vcpu);
u8 cr8 = kvm_register_read(vcpu, reg);
kvm_set_cr8(vcpu, cr8);
skip_emulated_instruction(vcpu);
if (irqchip_in_kernel(vcpu->kvm))
return 1;
- if (cr8_prev <= cr8)
- return 1;
vcpu->run->exit_reason = KVM_EXIT_SET_TPR;
return 0;
}

Which doesn't make any sense (anyone?). The failure is present even
without the patchset, and is fixed by the same hack, so a regression was
not introduced.

--
error compiling committee.c: too many arguments to function