[Qemu-devel] [RFC PATCH v2 0/9] vfio: capability chains, sparse mmap, device specific regions, IGD support

[Alex Williamson]

v2:

IGD support is greatly expanded.  Due to feedback on the previous
serious QEMU no longer maps the OpRegion to the guest, we simply fill
a buffer and expose it as fw_cfg.  We could still do the mapping in
the future if there's value to it.

New features include the use of host and LPC bridge config space
provided through new vfio device specific regions.  This eliminates
the need for QEMU to go poking around in pci-sysfs.  Additionally the
host and LPC changes are now initiated by vfio-pci upon finding the
necessary regions to support these.  Thus the igd_passthru=on machine
option is not needed for this series.  This series no longer has any
dependency on Gerd's previous IGD series.

Also included is PCI option ROM fixups, which automatically fixes the
device ID in the ROM and recalculates the checksum for ROMs loaded
through vfio.  This is necessary for IGD as the ROM vfio provides us
through the shadow ROM space typically has the wrong ID and bogus
checksum.  It would also be useful for anyone "soft modding" a card
by specifying a different device ID and manually hacking the ROM.

Finally is a quirk to handle stolen memory and requires cooperation
with SeaBIOS.  We need the vBIOS, as enabled by the ROM support
above, for lighting up laptop panels (at least for my SNB system),
but that vBIOS tries to make use of host stolen memory, which either
overlaps VM RAM or empty space, which leads to VM memory corruption
or DMAR faults respectively.  We can prevent this by intercepting
the vBIOS programming of the device to instead use a buffer allocated
by SeaBIOS.  I'm amazed this works, but it does... at least for me.
Comments and testing feedback welcome.  You'll need this QEMU patch
series, the latest vfio patch series (including the PCI reset path
on laptops), and a new SeaBIOS patch series.  Thanks,

Alex


v1:

This is the QEMU compliment to the vfio kernel capability chain
series.  This is RFC since it depends on those non-upstream kernel
changes.  Patch 1/ will be posted separately, it's somewhat unrelated,
but is in my build tree so I include it here for anyone that wants to
build this series.

This series includes sparse mmap support for avoiding mmaps over the
MSI-X vector table and device specific memory regions for IGD OpRegion
support.  MemoryRegions are significantly generalize for the former,
to make it really easy for each vfio region to be backed by none or
more mmap MemoryRegion.  The MSI-X vector table then either adds an
mmap region, or not via a legacy quirk or explicit sparse mmap
support.

IGD OpRegions are exposed as new device specific region, which simply
entails searching regions past those known for matching type and
sub-type regions that we know how to handle.  Writes to the OpRegion
register (ASL storage) pop the host OpRegion into VM system memory.
This isn't exactly like how real hardware works, but it makes for a
convenient implementation.  Alternatively we could pass the entire
OpRegion table via fw_cfg, but this makes write through to the host
impossible (if that's even useful).  This is certainly something that
I'm looking for comments about in this series.  Thanks,

Alex

---

Alex Williamson (9):
      vfio: Add sysfsdev property for pci & platform
      vfio: Wrap VFIO_DEVICE_GET_REGION_INFO
      vfio: Generalize region support
      vfio/pci: Convert all MemoryRegion to dynamic alloc and consistent 
functions
      linux-headers/vfio: Update for proposed capabilities list
      vfio: Enable sparse mmap capability
      vfio/pci: Intel IGD graphics support
      vfio/pci: Fixup PCI option ROMs
      vfio/pci: Intel IGD stolen memory quirk


 hw/arm/sysbus-fdt.c           |    2 
 hw/vfio/common.c              |  249 +++++++++++++++++--
 hw/vfio/pci-quirks.c          |  373 ++++++++++++++++++++++++++--
 hw/vfio/pci.c                 |  539 ++++++++++++++++++++++-------------------
 hw/vfio/pci.h                 |   18 +
 hw/vfio/platform.c            |  126 +++-------
 include/hw/vfio/vfio-common.h |   29 ++
 linux-headers/linux/vfio.h    |  101 ++++++++
 trace-events                  |   16 +
 9 files changed, 1047 insertions(+), 406 deletions(-)