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

From: Pierre Morel
Subject: Re: [Qemu-devel] [PATCH v2 0/7] s390x/pci: Improve zPCI to cover more cases
Date: Tue, 21 Nov 2017 19:10:06 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0

On 21/11/2017 11:52, Cornelia Huck wrote:
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

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.]

OK, thanks.
I wait for the answers for the points I am still not sure, (#define and broken English) and send a v3 with the corrections.

Best regards,


Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

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