Re: [PATCH 2/3] VFIO: VFIO_DEVICE_SET_ADDR_MAPPING command

Alex Williamson
2013-03-15T19:30:50Z

On Fri, 2013-03-15 at 15:26 +0800, Gavin Shan wrote:
> The address (domain/bus/slot/function) of the passed PCI device
> looks quite different from perspective of host and guest. Some
> architectures like PPC need to setup the mapping in host. The patch
> introduces additional VFIO device IOCTL command to address that.

Could you explain further how this will be used? How the device is
exposed to a guest is entirely a userspace construct, so why does vfio
need to know or care about this? I had assumed for AER that QEMU would
do the translation from host to guest address space.

> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
> ---
> include/uapi/linux/vfio.h | 16 ++++++++++++++++
> 1 files changed, 16 insertions(+), 0 deletions(-)
>
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 6e58d9b..ecc4f38 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -289,6 +289,22 @@ struct vfio_irq_set {
> */
> #define VFIO_DEVICE_RESET _IO(VFIO_TYPE, VFIO_BASE + 11)
>
> +/**
> + * VFIO_DEVICE_SET_ADDR_MAPPING - _IO(VFIO_TYPE, VFIO_BASE + 12)
> + *
> + * The address, which comprised of domain/bus/slot/function looks
> + * different between host and guest. We need to setup the mapping
> + * in host for some architectures like PPC so that the passed PCI
> + * devices could support RTAS smoothly.
> + */
> +struct vfio_addr_mapping {
> + __u64 buid;

What's a buid? Thanks,

Alex

> + __u8 bus;
> + __u8 slot;
> + __u8 func;
> +};
> +#define VFIO_DEVICE_SET_ADDR_MAPPING _IO(VFIO_TYPE, VFIO_BASE + 12)
> +
> /*
> * The VFIO-PCI bus driver makes use of the following fixed region and
> * IRQ index mapping. Unimplemented regions return a size of zero.