Re: [PATCH] hw/virtio: enable ioeventfd configuring for mmio

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Cc: pbonzini@redhat.com, alex.bennee@linaro.org, qemu-devel@nongnu.org
Subject: Re: [PATCH] hw/virtio: enable ioeventfd configuring for mmio
Date: Tue, 6 Apr 2021 06:02:57 -0400	[thread overview]
Message-ID: <20210406054157-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <d5119624-9658-2cbb-e1c7-9e85bd22b532@ispras.ru>

i tagged it for 6.1
pls remind me after release so it's not lost

On Mon, Apr 05, 2021 at 08:50:31AM +0300, Pavel Dovgalyuk wrote:
> ping
> 
> On 29.03.2021 10:43, Pavel Dovgalyuk wrote:
> > This patch adds ioeventfd flag for virtio-mmio configuration.
> > It allows switching ioeventfd on and off.
> > 
> > Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> > ---
> >   hw/virtio/virtio-mmio.c         |   11 ++++++++++-
> >   include/hw/virtio/virtio-mmio.h |    5 +++++
> >   2 files changed, 15 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
> > index 342c918ea7..5952471b38 100644
> > --- a/hw/virtio/virtio-mmio.c
> > +++ b/hw/virtio/virtio-mmio.c
> > @@ -36,7 +36,9 @@
> >   static bool virtio_mmio_ioeventfd_enabled(DeviceState *d)
> >   {
> > -    return kvm_eventfds_enabled();
> > +    VirtIOMMIOProxy *proxy = VIRTIO_MMIO(d);
> > +
> > +    return (proxy->flags & VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD) != 0;
> >   }
> >   static int virtio_mmio_ioeventfd_assign(DeviceState *d,
> > @@ -720,6 +722,8 @@ static Property virtio_mmio_properties[] = {
> >       DEFINE_PROP_BOOL("format_transport_address", VirtIOMMIOProxy,
> >                        format_transport_address, true),
> >       DEFINE_PROP_BOOL("force-legacy", VirtIOMMIOProxy, legacy, true),
> > +    DEFINE_PROP_BIT("ioeventfd", VirtIOMMIOProxy, flags,
> > +                    VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD_BIT, true),
> >       DEFINE_PROP_END_OF_LIST(),
> >   };
> > @@ -731,6 +735,11 @@ static void virtio_mmio_realizefn(DeviceState *d, Error **errp)
> >       qbus_create_inplace(&proxy->bus, sizeof(proxy->bus), TYPE_VIRTIO_MMIO_BUS,
> >                           d, NULL);
> >       sysbus_init_irq(sbd, &proxy->irq);
> > +
> > +    if (!kvm_eventfds_enabled()) {
> > +        proxy->flags &= ~VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD;
> > +    }
> > +
> >       if (proxy->legacy) {
> >           memory_region_init_io(&proxy->iomem, OBJECT(d),
> >                                 &virtio_legacy_mem_ops, proxy,
> > diff --git a/include/hw/virtio/virtio-mmio.h b/include/hw/virtio/virtio-mmio.h
> > index d4c4c386ab..090f7730e7 100644
> > --- a/include/hw/virtio/virtio-mmio.h
> > +++ b/include/hw/virtio/virtio-mmio.h
> > @@ -49,12 +49,17 @@ typedef struct VirtIOMMIOQueue {
> >       uint32_t used[2];
> >   } VirtIOMMIOQueue;
> > +#define VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD_BIT 1
> > +#define VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD \
> > +        (1 << VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD_BIT)
> > +
> >   struct VirtIOMMIOProxy {
> >       /* Generic */
> >       SysBusDevice parent_obj;
> >       MemoryRegion iomem;
> >       qemu_irq irq;
> >       bool legacy;
> > +    uint32_t flags;
> >       /* Guest accessible state needing migration and reset */
> >       uint32_t host_features_sel;
> >       uint32_t guest_features_sel;
> > 