Re: [PATCH v3 4/5] KVM: ioeventfd for virtio-ccw devices.

Cornelia Huck
2013-02-26T11:55:28Z

On Tue, 26 Feb 2013 12:55:36 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Mon, Feb 25, 2013 at 04:27:49PM +0100, Cornelia Huck wrote:
> > Enhance KVM_IOEVENTFD with a new flag that allows to attach to virtio-ccw
> > devices on s390 via the KVM_VIRTIO_CCW_NOTIFY_BUS.
> >
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> > ---
> > Documentation/virtual/kvm/api.txt | 8 ++++++++
> > include/uapi/linux/kvm.h | 3 +++
> > virt/kvm/eventfd.c | 14 ++++++++++++--
> > 3 files changed, 23 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> > index c2534c3..86232d6 100644
> > --- a/Documentation/virtual/kvm/api.txt
> > +++ b/Documentation/virtual/kvm/api.txt
> > @@ -1468,15 +1468,23 @@ struct kvm_ioeventfd {
> > __u8 pad[36];
> > };
> >
> > +For the special case of virtio-ccw devices on s390, the ioevent is matched
> > +to a subchannel/virtqueue tuple instead.
> > +
> > The following flags are defined:
> >
> > #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
> > #define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)
> > #define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)
> > +#define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
> > + (1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
> >
> > If datamatch flag is set, the event will be signaled only if the written value
> > to the registered address is equal to datamatch in struct kvm_ioeventfd.
> >
> > +For virtio-ccw devices, addr contains the subchannel id and datamatch the
> > +virtqueue index.
> > +
> >
> > 4.60 KVM_DIRTY_TLB
> >
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index 9a2db57..8f3e5ae 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -448,12 +448,15 @@ enum {
> > kvm_ioeventfd_flag_nr_datamatch,
> > kvm_ioeventfd_flag_nr_pio,
> > kvm_ioeventfd_flag_nr_deassign,
> > + kvm_ioeventfd_flag_nr_virtio_ccw_notify,
> > kvm_ioeventfd_flag_nr_max,
> > };
> >
> > #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
> > #define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)
> > #define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)
> > +#define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
> > + (1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
> >
> > #define KVM_IOEVENTFD_VALID_FLAG_MASK ((1 << kvm_ioeventfd_flag_nr_max) - 1)
> >
> > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> > index f0ced1a..8de3cd7 100644
> > --- a/virt/kvm/eventfd.c
> > +++ b/virt/kvm/eventfd.c
> > @@ -679,11 +679,16 @@ static int
> > kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
> > {
> > int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
> > - enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
> > + int ccw;
> > + enum kvm_bus bus_idx;
> > struct _ioeventfd *p;
> > struct eventfd_ctx *eventfd;
> > int ret;
> >
> > + ccw = args->flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY;
> > + bus_idx = pio ? KVM_PIO_BUS :
> > + ccw ? KVM_VIRTIO_CCW_NOTIFY_BUS :
> > + KVM_MMIO_BUS;
>
> May be better to rewrite using if/else.

Matter of taste, I guess. But I can do that.

>
> > /* must be natural-word sized */
> > switch (args->len) {
> > case 1:
> > @@ -759,11 +764,16 @@ static int
> > kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
> > {
> > int pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
> > - enum kvm_bus bus_idx = pio ? KVM_PIO_BUS : KVM_MMIO_BUS;
> > + int ccw;
> > + enum kvm_bus bus_idx;
> > struct _ioeventfd *p, *tmp;
> > struct eventfd_ctx *eventfd;
> > int ret = -ENOENT;
> >
> > + ccw = args->flags & KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY;
> > + bus_idx = pio ? KVM_PIO_BUS :
> > + ccw ? KVM_VIRTIO_CCW_NOTIFY_BUS :
> > + KVM_MMIO_BUS;
> > eventfd = eventfd_ctx_fdget(args->fd);
> > if (IS_ERR(eventfd))
> > return PTR_ERR(eventfd);
> > --
> > 1.7.12.4
>