On 15/01/16 14:56, Mark Rutland wrote: > Hi, > > [adding KVM people, given this is meant for virtualization] > > On Mon, Jan 11, 2016 at 09:45:43AM -0500, Sinan Kaya wrote: >> The Qualcomm Technologies HIDMA device has been designed to support >> virtualization technology. The driver has been divided into two to follow >> the hardware design. >> >> 1. HIDMA Management driver >> 2. HIDMA Channel driver >> >> Each HIDMA HW consists of multiple channels. These channels share some set >> of common parameters. These parameters are initialized by the management >> driver during power up. Same management driver is used for monitoring the >> execution of the channels. Management driver can change the performance >> behavior dynamically such as bandwidth allocation and prioritization. >> >> The management driver is executed in hypervisor context and is the main >> management entity for all channels provided by the device. > > You mention repeatedly that this is designed for virtualization, but > looking at the series as it stands today I can't see how this operates > from the host side. Nor the guest's, TBH. How do host and guest communicate, what is the infrastructure, how is it meant to be used? A lot of questions, and no answer whatsoever in this series. > > This doesn't seem to tie into KVM or VFIO, and as far as I can tell > there's no mechanism for associating channels with a particular virtual > address space (i.e. no configuration of an external or internal IOMMU), > nor pinning of guest pages to allow for DMA to occur safely. > > Given that, I'm at a loss as to how this would be used in a hypervisor > context. What am I missing? > > Are there additional patches, or do you have some userspace that works > with this in some limited configuration? Well, this looks so far like a code dumping exercise. I'd very much appreciate a HIDMA101 crash course: - How do host and guest communicate? - How is the integration performed in the hypervisor? - Does the HYP side requires any context switch (and how is that done)? - What makes it safe? Without any of this information (and pointer to the code to back it up), I'm very reluctant to take any of this. Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
