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SubjectRe: [PATCH] powerpc/xive: store server for masked interrupt in kvmppc_xive_set_xive()
On Fri, Nov 24, 2017 at 07:38:13AM +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2017-11-23 at 10:06 +0100, Laurent Vivier wrote:
> > This is needed to map kvmppc_xive_set_xive() behavior
> > to kvmppc_xics_set_xive().
> >
> > As we store the server, kvmppc_xive_get_xive() can return
> > the good value and we can also allow kvmppc_xive_int_on().
> >
> > Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> > ---
> > arch/powerpc/kvm/book3s_xive.c | 20 ++++++++------------
> > 1 file changed, 8 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
> > index bf457843e032..2781b8733038 100644
> > --- a/arch/powerpc/kvm/book3s_xive.c
> > +++ b/arch/powerpc/kvm/book3s_xive.c
> > @@ -584,10 +584,14 @@ int kvmppc_xive_set_xive(struct kvm *kvm, u32 irq, u32 server,
> > * we could initialize interrupts with valid default
> > */
> >
> > - if (new_act_prio != MASKED &&
> > - (state->act_server != server ||
> > - state->act_priority != new_act_prio))
> > - rc = xive_target_interrupt(kvm, state, server, new_act_prio);
> > + if (state->act_server != server ||
> > + state->act_priority != new_act_prio) {
> > + if (new_act_prio != MASKED)
> > + rc = xive_target_interrupt(kvm, state, server,
> > + new_act_prio);
> > + if (!rc)
> > + state->act_server = server;
> > + }
>
> That leads to another problem with this code. My current implementation
> is such that is a target queue is full, it will pick another target.
> But here, we still update act_server to the passed-in server and
> not the actual target...

So does that amount to a NAK?

> > /*
> > * Perform the final unmasking of the interrupt source
> > @@ -646,14 +650,6 @@ int kvmppc_xive_int_on(struct kvm *kvm, u32 irq)
> >
> > pr_devel("int_on(irq=0x%x)\n", irq);
> >
> > - /*
> > - * Check if interrupt was not targetted
> > - */
> > - if (state->act_priority == MASKED) {
> > - pr_devel("int_on on untargetted interrupt\n");
> > - return -EINVAL;
> > - }
> > -
>
> So my thinking here was that act_priority was never going to be MASKED
> except if the interrupt had never been targetted anywhere at machine
> startup time. Thus if act_priority is masked, the act_server field
> cannot be trusted.
>
> > /* If saved_priority is 0xff, do nothing */
> > if (state->saved_priority == MASKED)
> > return 0;

How do you think this should be fixed?

Laurent, are you reworking the patch at the moment?

Paul.

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