> -----Original Message-----
> From: Stefan Hajnoczi [mailto:stefa...@redhat.com]
> Sent: Wednesday, January 5, 2022 6:18 PM
> To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> <longpe...@huawei.com>
> Cc: m...@redhat.com; jasow...@redhat.com; sgarz...@redhat.com;
> coh...@redhat.com; pbonz...@redhat.com; Gonglei (Arei)
> <arei.gong...@huawei.com>; Yechuan <yech...@huawei.com>; Huangzhichao
> <huangzhic...@huawei.com>; qemu-devel@nongnu.org
> Subject: Re: [RFC 05/10] vdpa-dev: implement the realize interface
>
> On Wed, Jan 05, 2022 at 08:58:55AM +0800, Longpeng(Mike) wrote:
> > From: Longpeng <longpe...@huawei.com>
> >
> > Implements the .realize interface.
> >
> > Signed-off-by: Longpeng <longpe...@huawei.com>
> > ---
> > hw/virtio/vdpa-dev.c | 114 +++++++++++++++++++++++++++++++++++
> > include/hw/virtio/vdpa-dev.h | 8 +++
> > 2 files changed, 122 insertions(+)
> >
> > diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
> > index 790117fb3b..2d534d837a 100644
> > --- a/hw/virtio/vdpa-dev.c
> > +++ b/hw/virtio/vdpa-dev.c
> > @@ -15,9 +15,122 @@
> > #include "sysemu/sysemu.h"
> > #include "sysemu/runstate.h"
> >
> > +static void
> > +vhost_vdpa_device_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
> > +{
> > + /* Nothing to do */
> > +}
> > +
> > +static int vdpa_dev_get_info_by_fd(int fd, uint64_t cmd, Error **errp)
>
> This looks similar to the helper function in a previous patch but this
> time the return value type is int instead of uint32_t. Please make the
> types consistent.
>
OK.
> > +{
> > + int val;
> > +
> > + if (ioctl(fd, cmd, &val) < 0) {
> > + error_setg(errp, "vhost-vdpa-device: cmd 0x%lx failed: %s",
> > + cmd, strerror(errno));
> > + return -1;
> > + }
> > +
> > + return val;
> > +}
> > +
> > +static inline int vdpa_dev_get_queue_size(int fd, Error **errp)
> > +{
> > + return vdpa_dev_get_info_by_fd(fd, VHOST_VDPA_GET_VRING_NUM, errp);
> > +}
> > +
> > +static inline int vdpa_dev_get_vqs_num(int fd, Error **errp)
> > +{
> > + return vdpa_dev_get_info_by_fd(fd, VHOST_VDPA_GET_VQS_NUM, errp);
> > +}
> > +
> > +static inline int vdpa_dev_get_config_size(int fd, Error **errp)
> > +{
> > + return vdpa_dev_get_info_by_fd(fd, VHOST_VDPA_GET_CONFIG_SIZE, errp);
> > +}
> > +
> > static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> > {
> > + VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> > + VhostVdpaDevice *s = VHOST_VDPA_DEVICE(vdev);
> > + uint32_t device_id;
> > + int max_queue_size;
> > + int fd;
> > + int i, ret;
> > +
> > + fd = qemu_open(s->vdpa_dev, O_RDWR, errp);
> > + if (fd == -1) {
> > + return;
> > + }
> > + s->vdpa.device_fd = fd;
>
> This is the field I suggest exposing as a QOM property so it can be set
> from the proxy object (e.g. when the PCI proxy opens the vdpa device
> before our .realize() function is called).
>
OK.
> > +
> > + max_queue_size = vdpa_dev_get_queue_size(fd, errp);
> > + if (*errp) {
> > + goto out;
> > + }
> > +
> > + if (s->queue_size > max_queue_size) {
> > + error_setg(errp, "vhost-vdpa-device: invalid queue_size: %d
> (max:%d)",
> > + s->queue_size, max_queue_size);
> > + goto out;
> > + } else if (!s->queue_size) {
> > + s->queue_size = max_queue_size;
> > + }
> > +
> > + ret = vdpa_dev_get_vqs_num(fd, errp);
> > + if (*errp) {
> > + goto out;
> > + }
> > +
> > + s->dev.nvqs = ret;
>
> There is no input validation because we trust the kernel vDPA return
> values. That seems okay for now but if there is a vhost-user version of
> this in the future then input validation will be necessary to achieve
> isolation between QEMU and the vhost-user processes. I suggest including
> input validation code right away because it's harder to audit the code
> and fix missing input validation later on.
>
Make sense!
Should we only need to validate the upper boundary (e.g. <VIRTIO_QUEUE_MAX)?
> > + s->dev.vqs = g_new0(struct vhost_virtqueue, s->dev.nvqs);
> > + s->dev.vq_index = 0;
> > + s->dev.vq_index_end = s->dev.nvqs;
> > + s->dev.backend_features = 0;
> > + s->started = false;
> > +
> > + ret = vhost_dev_init(&s->dev, &s->vdpa, VHOST_BACKEND_TYPE_VDPA, 0,
> NULL);
> > + if (ret < 0) {
> > + error_setg(errp, "vhost-vdpa-device: vhost initialization
> failed: %s",
> > + strerror(-ret));
> > + goto out;
> > + }
> > +
> > + ret = s->dev.vhost_ops->vhost_get_device_id(&s->dev, &device_id);
>
> The vhost_*() API abstracts the ioctl calls but this source file and the
> PCI proxy have ioctl calls. I wonder if it's possible to move the ioctls
> calls into the vhost_*() API? That would be cleaner and also make it
> easier to add vhost-user vDPA support in the future.
We need these ioctls calls because we need invoke them before the vhost-dev
object is initialized.
