Re: [Qemu-devel] [PATCH v2 0/7] s390x/pci: Improve zPCI to cover more cases

[Cornelia Huck]

On Thu, 16 Nov 2017 18:51:48 +0100
Pierre Morel <address@hidden> wrote:

> This patch fixes the following BUG:
> Even a guest is able to detect virtio_pci device, the init function
> the Linux virtio_pci driver will hang because zPCI does not support
> the subregions used by virtio_pci.
> 
> It follows that right now the PCI support is very limited
> (e.g. pass through of a host vfio device)
> To enable features like virtio-pci several modifications needs to be
> done.
> 
> As already stated above, Virtio-PCI uses subregions, which may eventually
> be discontinuous inside bars instead of a single flat region often used
> by real devices.
> The address offset being formerly calculated from the BAR base address
> must be adapted to the subregions instead of to the single region.
> 
> This patch provides the new calculation for the three kind of BAR
> access, zPCI STORE, zPCI LOAD and zPCI STORE BLOCK done by zPCI.
> 
> We use the opportunity to
>  - enhance the fault detection for zPCI STORE and LOAD,
>  - enhance the fault detection and to provide the maximum STORE BLOCK
>    block size, maxstbl, for zPCI STORE BLOCK
>  - factor out part of the code used to calculate the offset and
>    access the BARs,
>  - factor out the code for endianess conversion.

I'll play with this a bit, but I think this is good for s390-next.

[I'd still like to play with this under tcg as well to make sure we are
endian-clean, but I'm making slower progress there than I hoped.]