> -----Original Message-----
> From: Cornelia Huck [mailto:coh...@redhat.com]
> Sent: Wednesday, January 5, 2022 6:46 PM
> To: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
> <longpe...@huawei.com>; stefa...@redhat.com; m...@redhat.com;
> jasow...@redhat.com; sgarz...@redhat.com
> Cc: pbonz...@redhat.com; Gonglei (Arei) <arei.gong...@huawei.com>; Yechuan
> <yech...@huawei.com>; Huangzhichao <huangzhic...@huawei.com>;
> qemu-devel@nongnu.org; Longpeng (Mike, Cloud Infrastructure Service Product
> Dept.) <longpe...@huawei.com>
> Subject: Re: [RFC 01/10] virtio: get class_id and pci device id by the virtio
> id
>
> On Wed, Jan 05 2022, "Longpeng(Mike)" <longpe...@huawei.com> wrote:
>
> > From: Longpeng <longpe...@huawei.com>
> >
> > Add helpers to get the "Transitional PCI Device ID" and "class_id" of the
> > deivce which is specificed by the "Virtio Device ID".
> >
> > These helpers will be used to build the generic vDPA device later.
> >
> > Signed-off-by: Longpeng <longpe...@huawei.com>
> > ---
> > hw/virtio/virtio-pci.c | 93 ++++++++++++++++++++++++++++++++++++++++++
> > hw/virtio/virtio-pci.h | 4 ++
> > 2 files changed, 97 insertions(+)
> >
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index 750aa47ec1..843085c4ea 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -19,6 +19,7 @@
> >
> > #include "exec/memop.h"
> > #include "standard-headers/linux/virtio_pci.h"
> > +#include "standard-headers/linux/virtio_ids.h"
> > #include "hw/boards.h"
> > #include "hw/virtio/virtio.h"
> > #include "migration/qemu-file-types.h"
> > @@ -213,6 +214,95 @@ static int virtio_pci_load_queue(DeviceState *d, int n,
> QEMUFile *f)
> > return 0;
> > }
> >
> > +typedef struct VirtIOPCIIDInfo {
> > + uint16_t vdev_id; /* virtio id */
> > + uint16_t pdev_id; /* pci device id */
> > + uint16_t class_id;
> > +} VirtIOPCIIDInfo;
> > +
> > +static const VirtIOPCIIDInfo virtio_pci_id_info[] = {
> > + {
> > + .vdev_id = VIRTIO_ID_NET,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_NET,
> > + .class_id = PCI_CLASS_NETWORK_ETHERNET,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_BLOCK,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_BLOCK,
> > + .class_id = PCI_CLASS_STORAGE_SCSI,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_CONSOLE,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_CONSOLE,
> > + .class_id = PCI_CLASS_COMMUNICATION_OTHER,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_SCSI,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_SCSI,
> > + .class_id = PCI_CLASS_STORAGE_SCSI,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_9P,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_9P,
> > + .class_id = PCI_BASE_CLASS_NETWORK,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_VSOCK,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_VSOCK,
> > + .class_id = PCI_CLASS_COMMUNICATION_OTHER,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_IOMMU,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_IOMMU,
> > + .class_id = PCI_CLASS_OTHERS,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_MEM,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_MEM,
> > + .class_id = PCI_CLASS_OTHERS,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_PMEM,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_PMEM,
> > + .class_id = PCI_CLASS_OTHERS,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_RNG,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_RNG,
> > + .class_id = PCI_CLASS_OTHERS,
> > + },
> > + {
> > + .vdev_id = VIRTIO_ID_BALLOON,
> > + .pdev_id = PCI_DEVICE_ID_VIRTIO_BALLOON,
> > + .class_id = PCI_CLASS_OTHERS,
> > + },
> > +};
> > +
> > +static VirtIOPCIIDInfo virtio_pci_get_id_info(uint16_t vdev_id)
> > +{
> > + VirtIOPCIIDInfo info = {};
> > + int i;
> > +
> > + for (i = 0; i < ARRAY_SIZE(virtio_pci_id_info); i++) {
> > + if (virtio_pci_id_info[i].vdev_id == vdev_id) {
> > + info = virtio_pci_id_info[i];
> > + break;
> > + }
> > + }
> > +
> > + return info;
> > +}
> > +
> > +uint16_t virtio_pci_get_pci_devid(uint16_t device_id)
> > +{
> > + return virtio_pci_get_id_info(device_id).pdev_id;
> > +}
> > +
> > +uint16_t virtio_pci_get_class_id(uint16_t device_id)
> > +{
> > + return virtio_pci_get_id_info(device_id).class_id;
> > +}
>
> What happens if these functions are called for a device_id that is not
> in the array, e.g. if we forgot to add a new id to the array?
>
It would return pdev_id=0 or class_id=0 as a result, the virtio device
with pdev_id=0 is undefined and class_id=0 is also treated as undefined
(PCI_CLASS_NOT_DEFINED), so the caller should check the returned value.
> Can the array be generated in some way?
For PCI Device ID:
- If we need to support Transitional VIRTIO devices, there's no algorithm
can map a VIRTIO ID to a PCI Device ID.
- If we only need to support 1.0+ VIRTIO devices, then we can calculate the
PCI Device ID based on the VIRTIO ID.
For Class ID, seems no way :(
