[libvirt] [PATCH] pci: Ignore 32-bit PCIe domains

[Daniel P. Berrangé]

On Fri, Mar 16, 2018 at 11:39:36AM -0600, Keith Busch wrote:
> Intel VMD creates secondary PCIe domain, where child devices in this
> domain are aggregated behind a single end point. Linux exposes these
> as special 32-bit domains, and devices in them are not individually
> assignable.

IIUC, your patch is addressing a problem for machines with a
specific Intel PCIe device type.

Is this  "domain >= USHRT_MAX" scenario specific to just this
Intel PCIe device type, or will such a high domain number indicate
the same semantics for devices from any vendor.

> This patch ignores devices in such domains as desired, and prevents
> logging excessive errors, like:
> 
>   internal error: dev->name buffer overflow: 10000:00:00.0
> 
> Cc: Jonathan Derrick <jonathan.derrick at intel.com>
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---
>  src/util/virpci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/util/virpci.c b/src/util/virpci.c
> index 55e4c3e49..53a6f2e51 100644
> --- a/src/util/virpci.c
> +++ b/src/util/virpci.c
> @@ -1762,6 +1762,13 @@ virPCIDeviceNew(unsigned int domain,
>      char *vendor = NULL;
>      char *product = NULL;
>  
> +
> +    /* Devices in a 32-bit domain are special. Currently applicable to Intel
> +     * VMD PCIe, where individual devices are not individually assignable.
> +     */
> +    if (domain > USHRT_MAX)
> +        return NULL;
> +
>      if (VIR_ALLOC(dev) < 0)
>          return NULL;
>  
> -- 
> 2.14.3
> 
> --
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Regards,
Daniel
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