Re: [Qemu-devel] [PATCH v2] pci: Error on PCI capability collisions

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

On Wed, Aug 24, 2011 at 02:29:30PM +0200, Jan Kiszka wrote:
> Nothing good can happen when we overlap capabilities. This may happen
> when plugging in assigned devices or when devices models contain bugs.
> Detect the overlap and report it.
> 
> Based on qemu-kvm commit by Alex Williamson.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Applied, thanks everyone.

> ---
>  hw/pci.c |   34 ++++++++++++++++++++++++++++++++++
>  1 files changed, 34 insertions(+), 0 deletions(-)
> 
> Changes in v2:
>  - properly find the conflicting CAP
>  - adjust error code
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 6124790..634e789 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -1811,6 +1811,25 @@ static uint8_t pci_find_capability_list(PCIDevice *pdev, uint8_t cap_id,
>      return next;
>  }
>  
> +static uint8_t pci_find_capability_at_offset(PCIDevice *pdev, uint8_t offset)
> +{
> +    uint8_t next, prev, found = 0;
> +
> +    if (!(pdev->used[offset])) {
> +        return 0;
> +    }
> +
> +    assert(pdev->config[PCI_STATUS] & PCI_STATUS_CAP_LIST);
> +
> +    for (prev = PCI_CAPABILITY_LIST; (next = pdev->config[prev]);
> +         prev = next + PCI_CAP_LIST_NEXT) {
> +        if (next <= offset && next > found) {
> +            found = next;
> +        }
> +    }
> +    return found;
> +}
> +
>  /* Patch the PCI vendor and device ids in a PCI rom image if necessary.
>     This is needed for an option rom which is used for more than one device. */
>  static void pci_patch_ids(PCIDevice *pdev, uint8_t *ptr, int size)
> @@ -1952,11 +1971,26 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
>                         uint8_t offset, uint8_t size)
>  {
>      uint8_t *config;
> +    int i, overlapping_cap;
> +
>      if (!offset) {
>          offset = pci_find_space(pdev, size);
>          if (!offset) {
>              return -ENOSPC;
>          }
> +    } else {
> +        for (i = offset; i < offset + size; i++) {
> +            overlapping_cap = pci_find_capability_at_offset(pdev, i);
> +            if (overlapping_cap) {
> +                fprintf(stderr, "ERROR: %04x:%02x:%02x.%x "
> +                        "Attempt to add PCI capability %x at offset "
> +                        "%x overlaps existing capability %x at offset %x\n",
> +                        pci_find_domain(pdev->bus), pci_bus_num(pdev->bus),
> +                        PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn),
> +                        cap_id, offset, overlapping_cap, i);
> +                return -EINVAL;
> +            }
> +        }
>      }
>  
>      config = pdev->config + offset;
> -- 
> 1.7.3.4