Re: [PATCH v1 0/1] Q35 Support

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Sun, Jun 18, 2023 at 06:22:01PM -0400, Joel Upham wrote:
> Q35 support using Qemu's device emulation.  I based the patches from 2017
> found on the mailing list here:
> https://lists.xenproject.org/archives/html/xen-devel/2018-03/msg01176.html
> 
> I have been using a version of these patches on Xen 4.16 with Qemu
> version 4.1 for over 6 months.  The guest VMs are very stable, and PCIe
> PT is working as was designed (all of the PCIe devices are on the root
> PCIe device).  I have successfully passed through GPUs, NICs, etc. I was
> asked by those in the community to attempt to once again upstream the
> patches.  I have them working with Seabios and OVMF (patches are needed
> to OVMF which I will be sending to the mailing list).  I will be sending
> my Qemu patches to their mailing list in hopes of getting everything
> upstreamed. The Qemu patches allow for the xenvbd to properly unplug the
> AHCI SATA device, and all xen pv windows drivers work as intended.
> 
> I used the original author of the patches to get a majority of this to work:
> Alexey Gerasimenko.  I fixed the patches to be in line with the upstream
> Qemu and Xen versions.  Any original issues may still exist; however, I
> am sure in time they can be improved. If the code doesn't exist then they 
> can't be actively looked at by the community.
> 
> I am not an expert on the Q35 chipset or PCIe technology.  This is my
> first patch to this mailing list.
> 
> Recap of changes to Qemu, only here for reference:
>   pc/xen: Xen Q35 support: provide IRQ handling for PCI devices
>   pc/q35: Apply PCI bus BSEL property for Xen PCI device hotplug
>   acpi/ich9: Multiple fixes for S3 support
>   acpi/pcihp: Allow for machines to hotplug when using Xen
>   isa/lpc_ich9: Write lpc configuration for xen IRQs
>   q35/acpi/xen: Provide ACPI PCI hotplug interface for Xen on Q35
>   q35/xen: Add Xen platform device support for Q35
>   q35: Fix incorrect values for PCIEXBAR masks
>   xen/pt: XenHostPCIDevice: provide functions for PCI Capabilities and
>     PCIe Extended Capabilities enumeration
>   xen/pt: avoid reading PCIe device type and cap version multiple times
>   xen/pt: determine the legacy/PCIe mode for a passed through device
>   xen/pt: Xen PCIe passthrough support for Q35: bypass PCIe topology
>     check
>   xen/pt: add support for PCIe Extended Capabilities and larger config
>     space
>   xen/pt: handle PCIe Extended Capabilities Next register
>   xen/pt: allow to hide PCIe Extended Capabilities
>   xen/pt: add Vendor-specific PCIe Extended Capability descriptor and
>     sizing
>   xen/pt: add fixed-size PCIe Extended Capabilities descriptors
>   xen/pt: add AER PCIe Extended Capability descriptor and sizing
>   xen/pt: add descriptors and size calculation for
>     RCLD/ACS/PMUX/DPA/MCAST/TPH/DPC PCIe Extended Capabilities
>   xen/pt: add Resizable BAR PCIe Extended Capability descriptor and
>     sizing
>   xen/pt: add VC/VC9/MFVC PCIe Extended Capabilities descriptors and
>     sizing
> 
> Changes that would be going to upstream Qemu:
>  hw/acpi/ich9.c                |   22 +-
>  hw/acpi/pcihp.c               |    6 +-
>  hw/core/machine.c             |   19 +
>  hw/i386/pc_piix.c             |    3 +-
>  hw/i386/pc_q35.c              |   39 +-
>  hw/i386/xen/xen-hvm.c         |    7 +-
>  hw/i386/xen/xen_platform.c    |   19 +-
>  hw/ide/ahci.c                 |    2 +-
>  hw/isa/lpc_ich9.c             |   53 +-
>  hw/isa/piix3.c                |    2 +-
>  hw/pci-host/q35.c             |   28 +-
>  hw/pci/pci.c                  |   17 +
>  hw/xen/xen-host-pci-device.c  |  106 +++-
>  hw/xen/xen-host-pci-device.h  |    6 +-
>  hw/xen/xen_pt.c               |   49 +-
>  hw/xen/xen_pt.h               |   19 +-
>  hw/xen/xen_pt_config_init.c   | 1103 ++++++++++++++++++++++++++++++---
>  include/hw/acpi/ich9.h        |    1 +
>  include/hw/acpi/pcihp.h       |    2 +
>  include/hw/boards.h           |    1 +
>  include/hw/i386/pc.h          |    3 +
>  include/hw/pci-host/q35.h     |    4 +-
>  include/hw/pci/pci.h          |    3 +
>  include/hw/southbridge/ich9.h |    1 +
>  include/hw/xen/xen.h          |    4 +-
>  qemu-options.hx               |    1 +
>  softmmu/datadir.c             |    1 -
>  softmmu/qdev-monitor.c        |    3 +-
>  stubs/xen-hw-stub.c           |    4 +-
>  29 files changed, 1396 insertions(+), 132 deletions(-)
> *** These patches are not found in this series, if they are supposed to
> be I will send them here as well. ***

It's unclear, do the QEMU patches depend on the Xen side?  I have a
suspicion you likely want to post them mostly at the same time, but
using two different patch series (one for Xen and one for QEMU).

> Recap of changes to Xen:
>   libacpi: new DSDT ACPI table for Q35
>   Makefile: build and use new DSDT table for Q35
>   hvmloader: add function to query an emulated machine type (i440/Q35)
>   hvmloader: add ACPI enabling for Q35
>   hvmloader: add Q35 DSDT table loading
>   hvmloader: add basic Q35 support
>   hvmloader: allocate MMCONFIG area in the MMIO hole + minor code
>     refactoring
>   hvmloader: seabios dsdt set to load correct config
>   hvmloader: ovmf dsdt set to load correct config
>   libxl: Q35 support (new option device_model_machine)
>   libxl: Xen Platform device support for Q35
>   libacpi: build ACPI MCFG table if requested
>   hvmloader: use libacpi to build MCFG table
>   docs: provide description for device_model_machine option
> 
> Joel Upham (1):
>   Q35 support

I'm afraid this needs to be split into a patch series, with proper
commit messages in order to be considered for review.  The current
huge patch is impossible to review at all.

Also you need to keep the Signed-off-by of the original author in the
patches.

Thanks, Roger.