Re: [PATCH v3 1/3] KVM: nVMX: Rework interception of IRQs and NMIs

[Paolo Bonzini <pbonzini@redhat.com>]

Il 06/03/2014 18:33, Jan Kiszka ha scritto:
> Move the check for leaving L2 on pending and intercepted IRQs or NMIs
> from the *_allowed handler into a dedicated callback. Invoke this
> callback at the relevant points before KVM checks if IRQs/NMIs can be
> injected. The callback has the task to switch from L2 to L1 if needed
> and inject the proper vmexit events.
> 
> The rework fixes L2 wakeups from HLT and provides the foundation for
> preemption timer emulation.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/x86/include/asm/kvm_host.h |  2 ++
>  arch/x86/kvm/vmx.c              | 67 +++++++++++++++++++++++------------------
>  arch/x86/kvm/x86.c              | 15 +++++++--
>  3 files changed, 53 insertions(+), 31 deletions(-)

With this patch do we still need

        if (is_guest_mode(vcpu) && nested_exit_on_intr(vcpu))
                /*
                 * We get here if vmx_interrupt_allowed() said we can't
                 * inject to L1 now because L2 must run. The caller will have
                 * to make L2 exit right after entry, so we can inject to L1
                 * more promptly.
                 */
                return -EBUSY;

in enable_irq_window?  If not, enable_nmi_window and enable_irq_window
can both return void.

And perhaps, vmx_check_nested_events could use the preemption timer trick
from Jailhouse instead of smp_send_reschedule.

Paolo