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Subject: Re: [PATCH 0/4] Pass zPCI hardware information via VFIO
From:   Matthew Rosato <mjrosato@linux.ibm.com>
To:     alex.williamson@redhat.com, cohuck@redhat.com,
        schnelle@linux.ibm.com
Cc:     pmorel@linux.ibm.com, borntraeger@de.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, gerald.schaefer@linux.ibm.com,
        linux-s390@vger.kernel.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Message-ID: <1f47cab8-af05-494f-1cf0-7b6d126e6367@linux.ibm.com>
Date:   Sat, 19 Sep 2020 11:50:25 -0400
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On 9/19/20 11:28 AM, Matthew Rosato wrote:
> This patchset provides a means by which hardware information about the
> underlying PCI device can be passed up to userspace (ie, QEMU) so that
> this hardware information can be used rather than previously hard-coded
> assumptions. A new VFIO region type is defined which holds this
> information.
> 
> A form of these patches saw some rounds last year but has been back-
> tabled for a while.  The original work for this feature was done by Pierre
> Morel. I'd like to refresh the discussion on this and get this finished up
> so that we can move forward with better-supporting additional types of
> PCI-attached devices.  The proposal here presents a completely different
> region mapping vs the prior approach, taking inspiration from vfio info
> capability chains to provide device CLP information in a way that allows
> for future expansion (new CLP features).
> 
> This feature is toggled via the CONFIG_VFIO_PCI_ZDEV configuration entry.

QEMU patchset that exploits the new region:
https://lists.gnu.org/archive/html/qemu-devel/2020-09/msg07076.html

> 
> Matthew Rosato (4):
>    s390/pci: stash version in the zpci_dev
>    s390/pci: track whether util_str is valid in the zpci_dev
>    vfio-pci/zdev: define the vfio_zdev header
>    vfio-pci/zdev: use a device region to retrieve zPCI information
> 
>   arch/s390/include/asm/pci.h         |   4 +-
>   arch/s390/pci/pci_clp.c             |   2 +
>   drivers/vfio/pci/Kconfig            |  13 ++
>   drivers/vfio/pci/Makefile           |   1 +
>   drivers/vfio/pci/vfio_pci.c         |   8 ++
>   drivers/vfio/pci/vfio_pci_private.h |  10 ++
>   drivers/vfio/pci/vfio_pci_zdev.c    | 242 ++++++++++++++++++++++++++++++++++++
>   include/uapi/linux/vfio.h           |   5 +
>   include/uapi/linux/vfio_zdev.h      | 116 +++++++++++++++++
>   9 files changed, 400 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/vfio/pci/vfio_pci_zdev.c
>   create mode 100644 include/uapi/linux/vfio_zdev.h
>