I have a query about the ARM SMMU driver. In the ARM smmu driver I see, that bus notifiers are registered for both amba and platform bus. Amba is the I/O interconnect, right? Why is bus notifier required for the amba bus? -Varun > -----Original Message----- > From: Yoder Stuart-B08248 > Sent: Thursday, September 05, 2013 11:21 PM > To: Wood Scott-B07421; Sethi Varun-B16395; Bhushan Bharat-R65777; 'Peter > Maydell'; 'Santosh Shukla'; 'Alex Williamson'; 'Alexander Graf'; > 'Antonios Motakis'; 'Christoffer Dall'; 'kim.phillips@xxxxxxxxxx' > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx; kvm-ppc@xxxxxxxxxxxxxxx; qemu- > devel@xxxxxxxxxx > Subject: vfio for platform devices - 9/5/2012 - minutes > > We had a call with those interested and/or working on vfio for platform > devices. > > Participants: Scott Wood, Varun Sethi, Bharat Bhushan, Peter Maydell, > Santosh Shukla, Alex Williamson, Alexander Graf, > Antonios Motakis, Christoffer Dall, Kim Phillips, > Stuart Yoder > > Several aspects to vfio for platform devices: > > 1. IOMMU groups > > -iommu driver needs to register a bus notifier for the platform bus > and create groups for relevant platform devices -Antonios is looking > at this for several ARM IOMMUs -PAMU (Freescale) driver already does > this > > 2. unbinding device from host > > PCI: > echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind > Platform: > echo ffe101300.dma > > /sys/bus/platform/devices/ffe101300.dma/driver/unbind > > -don't believe there are issues or work to do here > > 3. binding device to vfio-platform driver > > PCI: > echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id > > -this is probably the least understood issue-- platform drivers > register themselves with the bus for a specific "name" > string. That is matched with device tree "compatible" strings > later to bind a device to a driver > -we want is to have the vfio-platform driver to dynamically bind > to a variety of platform devices previously unknown to > vfio-platform > -ideally unbinding and binding could be an atomic operation -Alex W > pointed out that x86 could leverage this work so > keep that in mind in what we design > -Kim Phillips (Linaro) will start working on this > > 4. vfio kernel interface > > -exposes regions and interrupts to user space via FDs -there are 'info' > ioctls that allow getting info about > regions/interrupts such as size and type of interrupt -there is a > proposed extension to the 'info' ioctls that > provides device tree paths, allowing user space to coorelate > resources with the device tree > (https://lists.cs.columbia.edu/pipermail/kvmarm/2013-July/006237.html) > > 5. QEMU > -some key tasks > -interacts with vfio kernel interface > -registers memslots > -needs to dynamically get device hooked up to VM's > platform bus, including IRQs > -needs to generate device tree node > -a key point: we don't believe that platform device passthru > in QEMU can be solved in a completely generic way. There will > need to be device specific code for each device type being passed > through...to do things like generate device tree nodes -in general we > expect a relatively small number of device types > to be passed through to VMs > -Alex Graf is working on dynamic creation of platform devices > for the PPC e500 paravirt machine > -see: http://lists.nongnu.org/archive/html/qemu-devel/2013- > 07/msg03614.html > -first step is dynamically generating a virtual UART -that sets the > stage to create and create vfio devices backed > by real hardware > > There is a session at Linux Plumbers in a couple of weeks and further > discussions will happen there. > > Regards, > Stuart -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
