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

[Cornelia Huck <cohuck@redhat.com>]

On Tue,  7 Nov 2017 18:24:32 +0100
Pierre Morel <pmorel@linux.vnet.ibm.com> wrote:

> 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.
> 
> Virtio-PCI uses subregions, which may eventually be discontinuous
> inside bars instead of a single flat region.
> 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.
> 
> 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.

Will look at this later. Just a quick question: What kind of further
functionality is enabled by this? E.g., I can attach a virtio-net-pci
device right now, does this enable more virtio devices?

> 
> 
> Pierre Morel (7):
>   s390x/pci: factor out endianess conversion
>   s390x/pci: rework PCI STORE
>   s390x/pci: rework PCI LOAD
>   s390x/pci: rework PCI STORE BLOCK
>   s390x/pci: move the memory region read from pcilg
>   s390x/pci: move the memory region write from pcistg
>   s390x/pci: search for subregion inside the BARs
> 
>  hw/s390x/s390-pci-bus.h  |   1 +
>  hw/s390x/s390-pci-inst.c | 250 ++++++++++++++++++++++++++++-------------------
>  hw/s390x/s390-pci-inst.h |   2 +-
>  3 files changed, 153 insertions(+), 100 deletions(-)
>