Re: [Qemu-devel] [PATCH 2/5] pci: Add interface names to hybrid PCI devices

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Aug 23, 2017 at 07:14:42PM -0300, Eduardo Habkost wrote:
> The following devices support both PCIe and legacy PCI, by
> including special code to handle the QEMU_PCI_CAP_EXPRESS flag:
> 
> * vfio-pci (is_express=1, but legacy PCI handled by
>   vfio_populate_device())
> * vmxnet3 (is_express=0, but PCIe handled by vmxnet3_realize())
> * pvscsi (is_express=0, but PCIe handled by pvscsi_realize())
> * virtio-pci (is_express=0, but PCIe handled by
>   virtio_pci_dc_realize(), and additional legacy PCI code at
>   virtio_pci_realize())

Oh, the rules are even messier than that: QEMU_PCI_CAP_EXPRESS
controls _some_ of the code that makes a device become a PCI
Express device, but not every case.

In addition to vmxnet3, pvscsi and virtio-pci, PCIe caps
initialization is conditional on hcd-xhci (see below).

This means xhci is also a hybrid device.  But it doesn't seem to
clear QEMU_PCI_CAP_EXPRESS.  Doesn't it mean pci_config_size() is
broken if xhci is plugged to a legacy PCI bus?  How does it
affect migration?

Full list of pci_endpoint_cap*_init() calls:

hw/usb/hcd-xhci.c-    if (pci_bus_is_express(dev->bus) ||
hw/usb/hcd-xhci.c-        xhci_get_flag(xhci, XHCI_FLAG_FORCE_PCIE_ENDCAP)) {
hw/usb/hcd-xhci.c:        ret = pcie_endpoint_cap_init(dev, 0xa0);

hw/net/vmxnet3.c-    if (pci_is_express(pci_dev)) {
hw/net/vmxnet3.c-        if (pci_bus_is_express(pci_dev->bus)) {
hw/net/vmxnet3.c:            pcie_endpoint_cap_init(pci_dev, VMXNET3_EXP_EP_OFFSET);
hw/net/vmxnet3.c-        }

hw/scsi/megasas.c-    if (pci_is_express(dev)) {
hw/scsi/megasas.c:        pcie_endpoint_cap_init(dev, 0xa0);
hw/scsi/megasas.c-    }

hw/scsi/vmw_pvscsi.c-    if (pci_is_express(pci_dev) && pci_bus_is_express(pci_dev->bus)) {
hw/scsi/vmw_pvscsi.c:        pcie_endpoint_cap_init(pci_dev, PVSCSI_EXP_EP_OFFSET);
hw/scsi/vmw_pvscsi.c-    }

hw/virtio/virtio-pci.c-    if (pcie_port && pci_is_express(pci_dev)) {
hw/virtio/virtio-pci.c-        int pos;
hw/virtio/virtio-pci.c-
hw/virtio/virtio-pci.c:        pos = pcie_endpoint_cap_init(pci_dev, 0);


Note: on megasas, pci_endpoitn_cap_init() is conditional on
pci_is_express(), but pci_is_express() will never be false on
megasas-gen2 (because QEMU_PCI_CAP_EXPRESS is always set).


Full list of unconditional pci_endpoint_cap*init() calls:

hw/block/nvme.c:    pcie_endpoint_cap_init(&n->parent_obj, 0x80);

hw/net/e1000e.c:    if (pcie_endpoint_cap_v1_init(pci_dev, e1000e_pcie_offset) < 0) {

hw/pci-bridge/pcie_root_port.c:    rc = pcie_cap_init(d, rpc->exp_offset, PCI_EXP_TYPE_ROOT_PORT,
hw/pci-bridge/pcie_root_port.c-                       p->port, errp);

hw/pci-bridge/xio3130_downstream.c:    rc = pcie_cap_init(d, XIO3130_EXP_OFFSET, PCI_EXP_TYPE_DOWNSTREAM,
hw/pci-bridge/xio3130_downstream.c-                       p->port, errp);

hw/pci-bridge/xio3130_upstream.c:    rc = pcie_cap_init(d, XIO3130_EXP_OFFSET, PCI_EXP_TYPE_UPSTREAM,
hw/pci-bridge/xio3130_upstream.c-                       p->port, errp);

hw/pci-host/xilinx-pcie.c:    if (pcie_endpoint_cap_v1_init(dev, 0x80) < 0) {



> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  hw/net/vmxnet3.c       | 5 +++++
>  hw/scsi/vmw_pvscsi.c   | 2 ++
>  hw/vfio/pci.c          | 5 +++++
>  hw/virtio/virtio-pci.c | 5 +++++
>  4 files changed, 17 insertions(+)
> 
> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> index a19a7a3..61feacf 100644
> --- a/hw/net/vmxnet3.c
> +++ b/hw/net/vmxnet3.c
> @@ -2651,6 +2651,11 @@ static const TypeInfo vmxnet3_info = {
>      .instance_size = sizeof(VMXNET3State),
>      .class_init    = vmxnet3_class_init,
>      .instance_init = vmxnet3_instance_init,
> +    .interfaces = (InterfaceInfo[]) {
> +        { INTERFACE_PCIE_DEVICE },
> +        { INTERFACE_LEGACY_PCI_DEVICE },
> +        { }
> +    },
>  };
>  
>  static void vmxnet3_register_types(void)
> diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
> index 77d8b6f..40dfffa 100644
> --- a/hw/scsi/vmw_pvscsi.c
> +++ b/hw/scsi/vmw_pvscsi.c
> @@ -1300,6 +1300,8 @@ static const TypeInfo pvscsi_info = {
>      .class_init    = pvscsi_class_init,
>      .interfaces = (InterfaceInfo[]) {
>          { TYPE_HOTPLUG_HANDLER },
> +        { INTERFACE_PCIE_DEVICE },
> +        { INTERFACE_LEGACY_PCI_DEVICE },
>          { }
>      }
>  };
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 31e1edf..2b21391 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3023,6 +3023,11 @@ static const TypeInfo vfio_pci_dev_info = {
>      .class_init = vfio_pci_dev_class_init,
>      .instance_init = vfio_instance_init,
>      .instance_finalize = vfio_instance_finalize,
> +    .interfaces = (InterfaceInfo[]) {
> +        { INTERFACE_PCIE_DEVICE },
> +        { INTERFACE_LEGACY_PCI_DEVICE },
> +        { }
> +    },
>  };
>  
>  static void register_vfio_pci_dev_type(void)
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 8b0d6b6..8c0b6bf 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1958,6 +1958,11 @@ static const TypeInfo virtio_pci_info = {
>      .class_init    = virtio_pci_class_init,
>      .class_size    = sizeof(VirtioPCIClass),
>      .abstract      = true,
> +    .interfaces = (InterfaceInfo[]) {
> +        { INTERFACE_PCIE_DEVICE },
> +        { INTERFACE_LEGACY_PCI_DEVICE },
> +        { }
> +    },
>  };
>  
>  /* virtio-blk-pci */
> -- 
> 2.9.4
> 
> 

-- 
Eduardo