Re: [Qemu-devel] [PATCH v2 3/4] Add "Group Identifier" support to Red Hat PCI bridge.

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jun 26, 2018 at 10:49:33PM -0500, Venu Busireddy wrote:
> Add the "Vendor-Specific" capability to the Red Hat PCI bridge device
> "pci-bridge", to contain the "Group Identifier" (UUID) that will be
> used to pair a virtio device with the passthrough device attached to
> that bridge.
> 
> This capability is added to the bridge iff the "uuid" option is specified
> for the bridge.

I think the name should be more explicit. How about "failover-group-id"?

> 
> Signed-off-by: Venu Busireddy <venu.busireddy@oracle.com>

I'd like to also tweak the device id in this case,
to make it easier for guests to know it's a grouping bridge.

> ---
>  hw/pci-bridge/pci_bridge_dev.c |  8 ++++++++
>  hw/pci/pci_bridge.c            | 26 ++++++++++++++++++++++++++
>  include/hw/pci/pcie.h          |  1 +
>  3 files changed, 35 insertions(+)
> 
> diff --git a/hw/pci-bridge/pci_bridge_dev.c b/hw/pci-bridge/pci_bridge_dev.c
> index b2d861d216..bbbc6fa1c6 100644
> --- a/hw/pci-bridge/pci_bridge_dev.c
> +++ b/hw/pci-bridge/pci_bridge_dev.c
> @@ -71,6 +71,12 @@ static void pci_bridge_dev_realize(PCIDevice *dev, Error **errp)
>          bridge_dev->msi = ON_OFF_AUTO_OFF;
>      }
>  
> +    err = pci_bridge_vendor_init(dev, 0, errp);
> +    if (err < 0) {
> +        error_append_hint(errp, "Can't init group ID, error %d\n", err);
> +        goto vendor_cap_err;
> +    }
> +
>      err = slotid_cap_init(dev, 0, bridge_dev->chassis_nr, 0, errp);
>      if (err) {
>          goto slotid_error;
> @@ -109,6 +115,7 @@ slotid_error:
>      if (shpc_present(dev)) {
>          shpc_cleanup(dev, &bridge_dev->bar);
>      }
> +vendor_cap_err:
>  shpc_error:
>      pci_bridge_exitfn(dev);
>  }
> @@ -162,6 +169,7 @@ static Property pci_bridge_dev_properties[] = {
>                              ON_OFF_AUTO_AUTO),
>      DEFINE_PROP_BIT(PCI_BRIDGE_DEV_PROP_SHPC, PCIBridgeDev, flags,
>                      PCI_BRIDGE_DEV_F_SHPC_REQ, true),
> +    DEFINE_PROP_UUID(COMPAT_PROP_UUID, PCIDevice, uuid, false),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
> index 40a39f57cb..cb8b3dad2a 100644
> --- a/hw/pci/pci_bridge.c
> +++ b/hw/pci/pci_bridge.c
> @@ -34,12 +34,17 @@
>  #include "hw/pci/pci_bus.h"
>  #include "qemu/range.h"
>  #include "qapi/error.h"
> +#include "qemu/uuid.h"
>  
>  /* PCI bridge subsystem vendor ID helper functions */
>  #define PCI_SSVID_SIZEOF        8
>  #define PCI_SSVID_SVID          4
>  #define PCI_SSVID_SSID          6
>  
> +#define PCI_VENDOR_SIZEOF             20
> +#define PCI_VENDOR_CAP_LEN_OFFSET      2
> +#define PCI_VENDOR_GROUP_ID_OFFSET     4
> +
>  int pci_bridge_ssvid_init(PCIDevice *dev, uint8_t offset,
>                            uint16_t svid, uint16_t ssid,
>                            Error **errp)
> @@ -57,6 +62,27 @@ int pci_bridge_ssvid_init(PCIDevice *dev, uint8_t offset,
>      return pos;
>  }
>  
> +int pci_bridge_vendor_init(PCIDevice *d, uint8_t offset, Error **errp)
> +{
> +    int pos;
> +
> +    if (qemu_uuid_is_null(&d->uuid)) {
> +        return 0;
> +    }
> +
> +    pos = pci_add_capability(d, PCI_CAP_ID_VNDR, offset, PCI_VENDOR_SIZEOF,
> +            errp);
> +    if (pos < 0) {
> +        return pos;
> +    }
> +
> +    pci_set_word(d->config + pos + PCI_VENDOR_CAP_LEN_OFFSET,
> +            PCI_VENDOR_SIZEOF);
> +    memcpy(d->config + pos + PCI_VENDOR_GROUP_ID_OFFSET, &d->uuid,
> +            sizeof(QemuUUID));
> +    return pos;
> +}
> +
>  /* Accessor function to get parent bridge device from pci bus. */
>  PCIDevice *pci_bridge_get_device(PCIBus *bus)
>  {
> diff --git a/include/hw/pci/pcie.h b/include/hw/pci/pcie.h
> index b71e369703..b4189d0ce3 100644
> --- a/include/hw/pci/pcie.h
> +++ b/include/hw/pci/pcie.h
> @@ -82,6 +82,7 @@ struct PCIExpressDevice {
>  };
>  
>  #define COMPAT_PROP_PCP "power_controller_present"
> +#define COMPAT_PROP_UUID "uuid"
>  
>  /* PCI express capability helper functions */
>  int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type,