[RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts

[Caraman Mihai Claudiu-B02008]

> > This only disable soft interrupt for kvmppc_restart_interrupt() that
> > restarts interrupts if they were meant for the host:
> >
> > a. SOFT_DISABLE_INTS() only for BOOKE_INTERRUPT_EXTERNAL |
> > BOOKE_INTERRUPT_DECREMENTER | BOOKE_INTERRUPT_DOORBELL
> 
> Those aren't the only exceptions that can end up going to the host.  We
> could get a TLB miss that results in a heavyweight MMIO exit, etc.
>
> > And shouldn't we handle kvmppc_restart_interrupt() like the original
> > HOST flow?
> >
> > #define MASKABLE_EXCEPTION(trapnum, intnum, label, hdlr,
> > ack)           \
> >
> > START_EXCEPTION(label);                                         \
> >         NORMAL_EXCEPTION_PROLOG(trapnum, intnum,
> > PROLOG_ADDITION_MASKABLE)\
> >         EXCEPTION_COMMON(trapnum, PACA_EXGEN,
> > *INTS_DISABLE*)             \
> > 	...
> 
> Could you elaborate on what you mean?

I think Tiejun was saying that host has flags and replays only EE/DEC/DBELL
interrupts. There is special macro masked_interrupt_book3e in those exception
handlers that sets paca->irq_happened.

The list of replied interrupts is limited to asynchronous noncritical
interrupts which can be masked by MSR[EE] (therefore no TLB miss). Now
on KVM book3e we don't want to put them in the irq_happened lazy state
but rather to execute them directly, so there is no reason for exception
handling symmetry between host and guest.

-Mike