Re: [Qemu-devel] [PATCH v3 3/3] virtio: add vhost-user-fs-pci device

[Stefan Hajnoczi]

On Wed, Sep 18, 2019 at 09:27:21AM +0800, piaojun wrote:
> 
> 
> On 2019/9/18 0:00, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> > 
> > Add the PCI version of vhost-user-fs.
> > 
> > Launch QEMU like this:
> > 
> >   qemu -chardev socket,path=/tmp/vhost-fs.sock,id=chr0
> >        -device x-vhost-user-fs-pci,tag=myfs,chardev=chr0
> > 
> > Signed-off-by: Stefan Hajnoczi <address@hidden>
> > Signed-off-by: Sebastien Boeuf <address@hidden>
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > Reviewed-by: Cornelia Huck <address@hidden>
> > ---
> >  hw/virtio/Makefile.objs       |  1 +
> >  hw/virtio/vhost-user-fs-pci.c | 85 +++++++++++++++++++++++++++++++++++
> >  2 files changed, 86 insertions(+)
> >  create mode 100644 hw/virtio/vhost-user-fs-pci.c
> > 
> > diff --git a/hw/virtio/Makefile.objs b/hw/virtio/Makefile.objs
> > index 47ffbf22c4..e2f70fbb89 100644
> > --- a/hw/virtio/Makefile.objs
> > +++ b/hw/virtio/Makefile.objs
> > @@ -15,6 +15,7 @@ obj-$(CONFIG_VHOST_USER_FS) += vhost-user-fs.o
> >  obj-$(call land,$(CONFIG_VIRTIO_CRYPTO),$(CONFIG_VIRTIO_PCI)) += 
> > virtio-crypto-pci.o
> >  obj-$(CONFIG_VIRTIO_PMEM) += virtio-pmem.o
> >  common-obj-$(call land,$(CONFIG_VIRTIO_PMEM),$(CONFIG_VIRTIO_PCI)) += 
> > virtio-pmem-pci.o
> > +obj-$(call land,$(CONFIG_VHOST_USER_FS),$(CONFIG_VIRTIO_PCI)) += 
> > vhost-user-fs-pci.o
> >  obj-$(CONFIG_VHOST_VSOCK) += vhost-vsock.o
> >  
> >  ifeq ($(CONFIG_VIRTIO_PCI),y)
> > diff --git a/hw/virtio/vhost-user-fs-pci.c b/hw/virtio/vhost-user-fs-pci.c
> > new file mode 100644
> > index 0000000000..0e70985094
> > --- /dev/null
> > +++ b/hw/virtio/vhost-user-fs-pci.c
> > @@ -0,0 +1,85 @@
> > +/*
> > + * Vhost-user filesystem virtio device PCI glue
> > + *
> > + * Copyright 2018-2019 Red Hat, Inc.
> > + *
> > + * Authors:
> > + *  Dr. David Alan Gilbert <address@hidden>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> > + * (at your option) any later version.  See the COPYING file in the
> > + * top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/qdev-properties.h"
> > +#include "hw/virtio/vhost-user-fs.h"
> > +#include "virtio-pci.h"
> > +
> > +struct VHostUserFSPCI {
> > +    VirtIOPCIProxy parent_obj;
> > +    VHostUserFS vdev;
> > +};
> > +
> > +typedef struct VHostUserFSPCI VHostUserFSPCI;
> > +
> > +#define TYPE_VHOST_USER_FS_PCI "vhost-user-fs-pci-base"
> > +
> > +#define VHOST_USER_FS_PCI(obj) \
> > +        OBJECT_CHECK(VHostUserFSPCI, (obj), TYPE_VHOST_USER_FS_PCI)
> > +
> > +static Property vhost_user_fs_pci_properties[] = {
> > +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
> > +                       DEV_NVECTORS_UNSPECIFIED),
> > +    DEFINE_PROP_END_OF_LIST(),
> > +};
> > +
> > +static void vhost_user_fs_pci_realize(VirtIOPCIProxy *vpci_dev, Error 
> > **errp)
> > +{
> > +    VHostUserFSPCI *dev = VHOST_USER_FS_PCI(vpci_dev);
> > +    DeviceState *vdev = DEVICE(&dev->vdev);
> > +
> > +    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
> > +        vpci_dev->nvectors = dev->vdev.conf.num_request_queues + 1;
> > +    }
> > +
> > +    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
> > +    object_property_set_bool(OBJECT(vdev), true, "realized", errp);
> > +}
> > +
> > +static void vhost_user_fs_pci_class_init(ObjectClass *klass, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
> > +    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
> > +    k->realize = vhost_user_fs_pci_realize;
> > +    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
> > +    dc->props = vhost_user_fs_pci_properties;
> > +    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
> > +    pcidev_k->device_id = 0; /* Set by virtio-pci based on virtio id */
> 
> Why not set *PCI_DEVICE_ID_VIRTIO_FS* here just like virtio_blk? I'm
> not very familiar with this code, and just compare it with the other
> same logic.

The comment indicates that virtio-pci computes the correct PCI Device ID
based on the VIRTIO Device ID.  The PCI Device ID depends on the
Legacy/Transitional/Modern mode supported by the device and therefore
cannot be hardcoded.  If we set it here it will be overwritten later
anyway.

Stefan

signature.asc
Description: PGP signature