These patches were born after trying the current work on device
passthrough (see thread "[Qemu-devel] [RFC v2 0/6] KVM platform device
passthrough") with a DMA330 and FastModels. This work want to be the
starting point for dicussion on some aspects related to the next VFIO
platform development:
- [PATCH 1/4] Add a way to allocate memory region from a user pointer
for devices, and not exclusively for RAM. This is useful to exclude
the devices bound to VFIO from being DMA mapped by the VFIO memory
listener.
- [PATCH 2/4] Addition of the exec flag to the DMA mappings. This is
mandatory only for the ARM SMMU: in its next version VFIO will be able
to tell if the flag is supported.
- [PATCH 3/4] Possibility to bind a wider class of devices. In
particular the patch proposes a solution to enhance a bit the device
tree nodes generation, allowing to specify more than one compatibility
property (handy for AMBA devices). This was required by the DMA330
that needs “arm,pl330”,”arm,primecell” as compatibility string,
together with a clock source defined in the device tree. In the future
VFIO will be able to tell if we are dealing with an AMBA device; before
that, we have to rely on the compatibility string to state that.
- [PATCH 4/4] Another approach to handle the EOI, starting from the
assumption that we know in advance the location of the interrupt clear
register of the device. Testing the reference patches I was noticing
that the EOI mechanism was disabling the interrupt three times,
because the kernel driver was reading some registers in the timer
window before actually clearing the interrupt. This is of course
another workaround and not the definitive solution until we can rely
on a proper callback from the VGIC (something that we will see in a
future version of VFIO for platform devices).
These patches are based on the QEMU branch mentioned in the original
thread ("[Qemu-devel] [RFC v2 0/6] KVM platform device passthrough").
Alvise Rigo (4):
Allocate non-RAM MemoryRegion from user pointer
Add EXEC_FLAG to VFIO DMA mappings
Add AMBA devices support to VFIO
MemoryRegion with EOI callbacks for VFIO Platform devices
exec.c | 2 +-
hw/arm/virt.c | 39 +++++++++--
hw/vfio/common.c | 3 +
hw/vfio/platform.c | 158 ++++++++++++++++++++++++++++++++++++++++++---
include/exec/memory.h | 16 +++++
linux-headers/linux/vfio.h | 1 +
memory.c | 14 ++++
memory_mapping.c | 2 +-
8 files changed, 220 insertions(+), 15 deletions(-)
--
1.8.3.2
