[Qemu-devel] [PATCH v2 0/2] Add global device ID in virt machine

[Diana Craciun]

The NXP DPAA2 is a hardware architecture designed for high-speeed network
packet processing. The DPAA2 hardware components are managed by a hardware
component called the Management Complex (or MC) which provides an
object-base abstraction for software drivers to use the DPAA2 hardware.
For more details you can see: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/staging/fsl-mc/README.txt?h=v4.10

The interrupts generated by the DPAA2 hardware components are MSIs. We will add
support for direct assigning these DPAA2 components/objects to a virtual 
machine. However, this will add the need to expand the MSI usage in QEMU.

Currently the MSIs in QEMU are pretty much tied to PCI. For ARM the
GIC ITS is using a device ID for interrupt translation. Currently, for
PCI, the requester ID is used as device ID. This will not work when
we add another entity that needs also a device ID which is supposed to
be unique across the system.

My proposal is to add a static allocation in the virt machine. I considered
that this allocation is specific to each machine/platform. Currently only
virt machine has it, but other implementations may use the same mechanism
as well.
So, I used a static allocation with this formula:

DeviceID = zero_extend( RequesterID[15:0] ) + 0x10000 * Constant

This formula was taken from SBSA spec (Appendix I: DeviceID generation and
ITS groups). In case of QEMU the constant will be different for each entity.
In this way a unique DeviceID will be generated and the device ID will be
derived from a requesterID (in case of PCI) or other means in case of other
entities.

The implementation is generic as there might be in the future other non-pci 
devices
that are using MSIs or IOMMU. Any architecture can use it, though currently
only the ARM architecture is using the function that retrieves the stream ID. I
did not change all the replacements of the pci_requester_id (with pci_stream_id)
in the code (although if the constant is 0, the stream_id is equal with 
requester_id).
The other architectures (e.g. intel iommu code) assume that the ID is the
requester ID.

Tested on NXP LS2080 platform.

History:

v1->v2
------
- the stream ID was added as a field in the pci device structure in order
not to traverse the PCI hierarchy each time a MSI is sent.


Diana Craciun (2):
  Increased the size of requester_id field from MemTxAttrs
  Add a unique ID in the virt machine to be used as device ID

 hw/arm/virt.c                          | 26 ++++++++++++++++++++++++++
 hw/i386/amd_iommu.c                    |  2 +-
 hw/i386/intel_iommu.c                  |  2 +-
 hw/intc/arm_gicv3_its_common.c         |  2 +-
 hw/intc/arm_gicv3_its_kvm.c            |  2 +-
 hw/pci-host/gpex.c                     |  6 ++++++
 hw/pci/msi.c                           |  2 +-
 hw/pci/pci.c                           | 25 +++++++++++++++++++++++++
 include/exec/memattrs.h                |  4 ++--
 include/hw/arm/virt.h                  |  1 +
 include/hw/intc/arm_gicv3_its_common.h |  2 +-
 include/hw/pci-host/gpex.h             |  2 ++
 include/hw/pci/pci.h                   |  8 ++++++++
 kvm-all.c                              |  4 ++--
 14 files changed, 78 insertions(+), 10 deletions(-)

-- 
2.5.5