On Thu, Jun 25, 2020 at 09:07:04AM +0200, Claudio Fontana wrote:
> Hi Roman,
>
> On 6/25/20 12:58 AM, Roman Bolshakov wrote:
> > HVF doesn't have a CPU kick and without it it's not possible to perform
> > an action on CPU thread until a VMEXIT happens. The kick is also needed
> > for timely interrupt delivery.
> >
> > Existing implementation of CPU kick sends SIG_IPI (aka SIGUSR1) to vCPU
> > thread, but it's different from what hv_vcpu_interrupt does. The latter
> > one results in invocation of mp_cpus_kick() in XNU kernel [1].
> >
> > While at it, correct type of hvf_fd to the type of hv_vcpuid_t to avoid
> > compilation warnings.
> >
> > 1. https://opensource.apple.com/source/xnu/xnu-6153.81.5/osfmk/i386/mp.c
> >
> > Cc: Cameron Esfahani <di...@apple.com>
> > Signed-off-by: Roman Bolshakov <r.bolsha...@yadro.com>
> > ---
> > cpus.c | 13 +++++++++----
> > include/hw/core/cpu.h | 2 +-
> > include/sysemu/hvf.h | 1 +
> > target/i386/hvf/hvf.c | 11 +++++++++++
> > 4 files changed, 22 insertions(+), 5 deletions(-)
> >
> > diff --git a/cpus.c b/cpus.c
> > index 26709677d3..36f38ce5c8 100644
> > --- a/cpus.c
> > +++ b/cpus.c
> > @@ -1783,10 +1783,15 @@ static void qemu_cpu_kick_thread(CPUState *cpu)
> > return;
> > }
> > cpu->thread_kicked = true;
> > - err = pthread_kill(cpu->thread->thread, SIG_IPI);
> > - if (err && err != ESRCH) {
> > - fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
> > - exit(1);
> > +
> > + if (hvf_enabled()) {
> > + hvf_vcpu_kick(cpu);
>
> could this be moved to qemu_cpu_kick, where we have already the ifs for
> accelerator types tcg and hax?
>
Hi Claudio,
I did this because of cpu->thread_kicked which is not set or tested in
qemu_cpu_kick(). It's not used for tcg and mttcg but hax does seem to
use the qemu_cpu_kick_thread() and additionally sets cpu->exit_request
in qemu_cpu_kick(). There's a difference between hax/kvm and hvf, they
use different ways of siginalling the kick. hax/kvm use POSIX signals
while HVF sends an IPI from the host LAPIC to deliver the kick. The
patch highlights the difference.
As far as I understand if thread_kicked is set, multiple cpu kicks are
coalesced until thread_kicked is cleared. So, the answer to your
question: It could be moved to qemu_cpu_kick but then kick debouncing
should be duplicated inside hvf_vcpu_kick().
Regards,
Roman
> Not terribly important if then my cpus-refactoring goes forward, but on its
> own that should be the proper place for if (hvf_enabled()) I think.
>
>
>
> > + } else {
> > + err = pthread_kill(cpu->thread->thread, SIG_IPI);
> > + if (err && err != ESRCH) {
> > + fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
> > + exit(1);
> > + }
> > }
> > #else /* _WIN32 */
> > if (!qemu_cpu_is_self(cpu)) {
