[Qemu-devel] Re: [PATCH 03/15] kvm: Install optimized interrupt handlers

[Marcelo Tosatti <mtosatti@redhat.com>]

On Sat, Mar 05, 2011 at 07:11:53PM +0100, Jan Kiszka wrote:
> On 2011-03-05 16:37, Marcelo Tosatti wrote:
> > On Fri, Mar 04, 2011 at 11:20:00AM +0100, Jan Kiszka wrote:
> >> KVM only requires to set the raised IRQ in CPUState and, if the user
> >> space irqchip is used, to kick the receiving vcpu if it is remote.
> >>
> >> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> >> ---
> >>  kvm-all.c |   17 +++++++++++++++++
> >>  1 files changed, 17 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/kvm-all.c b/kvm-all.c
> >> index 226843c..c460d45 100644
> >> --- a/kvm-all.c
> >> +++ b/kvm-all.c
> >> @@ -650,6 +650,20 @@ static CPUPhysMemoryClient kvm_cpu_phys_memory_client = {
> >>      .log_stop = kvm_log_stop,
> >>  };
> >>  
> >> +static void kvm_handle_interrupt(CPUState *env, int mask)
> >> +{
> >> +    env->interrupt_request |= mask;
> >> +
> > 
> > If the env->interrupt_request request is processed in userspace, such as
> > MCE, the kick is still necessary for irqchip case. CPU_INTERRUPT_DEBUG
> > is another example, no?
> 
> [this probably targeted kvm_handle_interrupt_kernel_irqchip]
> 
> In principle, you are right. But MCE must be injected synchronously over
> the target VCPU, see do_inject_x86_mce, and CPU_INTERRUPT_DEBUG is also
> synchronous and not even used in KVM mode.

CPU_INTERRUPT_NMI from monitor?

Don't see what gain you expect from avoiding the signal in this case.