Re: [Qemu-devel] [PATCH v2] e1000e: Prevent MSI/MSI-X storms

[Jason Wang]

On 2018年06月30日 14:13, Jan Kiszka wrote:
> On 2018-04-05 19:41, Jan Kiszka wrote:
> > From: Jan Kiszka <address@hidden>
> >
> > Only signal MSI/MSI-X events on rising edges. So far we re-triggered the
> > interrupt sources even if the guest did no consumed the pending one,
> > easily causing interrupt storms.
> >
> > Issue was observable with Linux 4.16 e1000e driver when MSI-X was used.
> > Vector 2 was causing interrupt storms after the driver activated the
> > device.
> >
> > Signed-off-by: Jan Kiszka <address@hidden>
> > ---
> >
> > Changes in v2:
> >   - also update msi_causes_pending after EIAC changes (required because
> >     there is no e1000e_update_interrupt_state after that
> >
> >   hw/net/e1000e_core.c | 11 +++++++++++
> >   hw/net/e1000e_core.h |  2 ++
> >   2 files changed, 13 insertions(+)
> >
> > diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
> > index c93c4661ed..d6ddd59986 100644
> > --- a/hw/net/e1000e_core.c
> > +++ b/hw/net/e1000e_core.c
> > @@ -2027,6 +2027,7 @@ e1000e_msix_notify_one(E1000ECore *core, uint32_t cause, 
> > uint32_t int_cfg)
> >       }
> >   
> >       core->mac[ICR] &= ~effective_eiac;
> > +    core->msi_causes_pending &= ~effective_eiac;
> >   
> >       if (!(core->mac[CTRL_EXT] & E1000_CTRL_EXT_IAME)) {
> >           core->mac[IMS] &= ~effective_eiac;
> > @@ -2123,6 +2124,13 @@ e1000e_send_msi(E1000ECore *core, bool msix)
> >   {
> >       uint32_t causes = core->mac[ICR] & core->mac[IMS] & ~E1000_ICR_ASSERTED;
> >   
> > +    core->msi_causes_pending &= causes;
> > +    causes ^= core->msi_causes_pending;
> > +    if (causes == 0) {
> > +        return;
> > +    }
> > +    core->msi_causes_pending |= causes;
> > +
> >       if (msix) {
> >           e1000e_msix_notify(core, causes);
> >       } else {
> > @@ -2160,6 +2168,9 @@ e1000e_update_interrupt_state(E1000ECore *core)
> >       core->mac[ICS] = core->mac[ICR];
> >   
> >       interrupts_pending = (core->mac[IMS] & core->mac[ICR]) ? true : false;
> > +    if (!interrupts_pending) {
> > +        core->msi_causes_pending = 0;
> > +    }
> >   
> >       trace_e1000e_irq_pending_interrupts(core->mac[ICR] & core->mac[IMS],
> >                                           core->mac[ICR], core->mac[IMS]);
> > diff --git a/hw/net/e1000e_core.h b/hw/net/e1000e_core.h
> > index 7d8ff41890..63a15510cc 100644
> > --- a/hw/net/e1000e_core.h
> > +++ b/hw/net/e1000e_core.h
> > @@ -109,6 +109,8 @@ struct E1000Core {
> >       NICState *owner_nic;
> >       PCIDevice *owner;
> >       void (*owner_start_recv)(PCIDevice *d);
> > +
> > +    uint32_t msi_causes_pending;
> >   };
> >   
> >   void
> Ping again, this one is still open.
>
> Jan

Sorry for the late.

Just one thing to confirm, I think the reason that we don't need to 
migrate msi_cause_pending is that it can only lead at most one more 
signal of MSI on destination?

Thanks