Re: [PATCH] hw/pci/pci_bridge: ensure PCIe slots have only one slot

[Michael S. Tsirkin]

On Mon, Jul 04, 2022 at 01:25:14PM +0300, Roman Kagan wrote:
> It's possible to create non-working configurations by attaching a device
> to a derivative of PCIe slot (pcie-root-port, ioh3420, etc) and
> specifying a slot number other that zero, e.g.:
> 
>     -device pcie-root-port,id=s0,... \
>     -device virtio-blk-pci,bus=s0,addr=4,...
> 
> Make QEMU reject such configurations and only allow addr=0 on the
> secondary bus of a PCIe slot.
> 
> Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
> ---
>  hw/pci/pci_bridge.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
> index da34c8ebcd..8b38d5ad3d 100644
> --- a/hw/pci/pci_bridge.c
> +++ b/hw/pci/pci_bridge.c
> @@ -33,6 +33,7 @@
>  #include "qemu/units.h"
>  #include "hw/pci/pci_bridge.h"
>  #include "hw/pci/pci_bus.h"
> +#include "hw/pci/pcie_port.h"
>  #include "qemu/module.h"
>  #include "qemu/range.h"
>  #include "qapi/error.h"
> @@ -386,6 +387,10 @@ void pci_bridge_initfn(PCIDevice *dev, const char 
> *typename)
>      br->windows = pci_bridge_region_init(br);
>      QLIST_INIT(&sec_bus->child);
>      QLIST_INSERT_HEAD(&parent->child, sec_bus, sibling);
> +
> +    if (PCIE_SLOT(dev)) {
> +        sec_bus->slot_reserved_mask = ~1u;
> +    }


Please add comments explaining what's going on.

>  }
>  
>  /* default qdev clean up function for PCI-to-PCI bridge */
> -- 
> 2.36.1