[PATCH 1/2] irqchip/gicv3-its: Support share device ID

[Varun Sethi]

Hi Minghuan,

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-
> bounces at lists.infradead.org] On Behalf Of Marc Zyngier
> Sent: Thursday, April 16, 2015 5:21 PM
> To: Lian Minghuan-B31939
> Cc: Jason Cooper; Arnd Bergmann; linux-pci at vger.kernel.org; Will Deacon;
> Yoder Stuart-B08248; Wood Scott-B07421; Bjorn Helgaas; Hu Mingkai-B21284;
> Zang Roy-R61911; Thomas Gleixner; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH 1/2] irqchip/gicv3-its: Support share device ID
> 
> Minghuan,
> 
> On 16/04/15 11:57, Minghuan.Lian at freescale.com wrote:
> 
> Please include the relevant people (Will Deacon for questions about the
> SMMU), and avoid top posting, it makes it very hard to follow a discussion.
> 
> > I still have a couple of questions,
> > 1. If I add a new flag and all PCI DEVID will be replaced with a fixed
> > ID,  does SMMU can work correctly? For example, If we insert an
> > Ethernet card with two ports, a port is assigned to kvm1, another port
> > is assigned to kvm2. In this case, we should use one or two fixed ID?
> 
> That completely depends on what the SMMU sees. If it sees the same ID,
> you won't be able to perform any form of isolation. But I have no idea how
> your hardware works, so maybe explaining in details how this is constructed
> will help.
> 

We would need separate stream IDs and iommu groups for endpoints, to assign them to different VMs. We would have to set up the stream ID to device ID translation table during device probe, via add_device callback. While setting the device id for the interrupt translation table, you would have to get streamID corresponding to a given PCIe device ID. Again, I don't think that we should consider the TBUID, while setting the ITT device id.

-Varun