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Date: Tue, 23 Aug 2011 21:17:51 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20110823181751.GB6326@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] pci: Error on PCI capability collisions
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Alex Williamson <alex.williamson@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On Tue, Aug 23, 2011 at 07:28:08PM +0200, Jan Kiszka wrote:
> From: Alex Williamson <alex.williamson@redhat.com>
> 
> Nothing good can happen when we overlap capabilities
> 
> [ Jan: rebased over qemu, minor formatting ]
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

I'll stick an assert there instead. Normal devices
don't generate overlapping caps unless there's a bug,
and device assignment should do it's own checks.

I really have a mind to rip out the used array too.

> ---
>  hw/pci.c |   14 ++++++++++++++
>  1 files changed, 14 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/pci.c b/hw/pci.c
> index 6124790..ff20631 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -1952,11 +1952,25 @@ int pci_add_capability(PCIDevice *pdev, uint8_t cap_id,
>                         uint8_t offset, uint8_t size)
>  {
>      uint8_t *config;
> +    int i;
> +
>      if (!offset) {
>          offset = pci_find_space(pdev, size);
>          if (!offset) {
>              return -ENOSPC;
>          }
> +    } else {
> +        for (i = offset; i < offset + size; i++) {
> +            if (pdev->used[i]) {
> +                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, pdev->config_map[i], i);
> +                return -EFAULT;
> +            }
> +        }
>      }
>  
>      config = pdev->config + offset;
> -- 
> 1.7.3.4