Re: [PATCH 1/1] target/ppc: fix 'skip KVM' cond in cpu_interrupt_exittb()

[Fabiano Rosas <farosas@linux.ibm.com>]

Daniel Henrique Barboza <danielhb413@gmail.com> writes:

> cpu_interrupt_exittb() was introduced by commit 044897ef4a22
> ("target/ppc: Fix system lockups caused by interrupt_request state
> corruption") as a way to wrap cpu_interrupt() helper in BQL.
>
> After that, commit 6d38666a8931 ("ppc: Ignore the CPU_INTERRUPT_EXITTB
> interrupt with KVM") added a condition to skip this interrupt if we're
> running with KVM.
>
> Problem is that the change made by the above commit, testing for
> !kvm_enabled() at the start of cpu_interrupt_exittb():
>
> static inline void cpu_interrupt_exittb(CPUState *cs)
> {
>     if (!kvm_enabled()) {
>         return;
>     }
>     (... do cpu_interrupt(cs, CPU_INTERRUPT_EXITTB) ...)
>
> is doing the opposite of what it intended to do. This will return
> immediately if not kvm_enabled(), i.e. it's a emulated CPU, and if
> kvm_enabled() it will proceed to fire CPU_INTERRUPT_EXITTB.
>
> Fix the 'skip KVM' condition so the function is a no-op when
> kvm_enabled().
>
> CC: Greg Kurz <groug@kaod.org>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/809
> Fixes: 6d38666a8931 ("ppc: Ignore the CPU_INTERRUPT_EXITTB interrupt with KVM")
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>