RE: [PATCH v2 0/3] KVM: arm/arm64: Allow to use KVM without in-kernel irqchip

2015-07-19 Thread Pavel Fedin
 Hello!

 Believe it or not, we're not only patch reviewing machines, and if you
 count the number of pending patches, you'll quickly notice that yours
 are basically noise in the grand scheme of things.
 
 So please cut us some slack.

 What do you mean exactly? Stop discussions and just do everything you suggest 
before respin? Plz
don't attempt to read this between lines, i can be bad at communication; this 
is not a complain
and/or hurt indication, i am just asking. :)

  complete implementation of API which allows to emulate GIC in userspace by
  qemu, and now i can run any virtual machine, including generic timer, on
  vGIC-less machine. RasPI-2 is expected to benefit too.
 
 Do you mean feeding interrupts back to userspace?

 Yes, exactly. I have a working proof-of-concept here.

 How is that going to
 work with the active-timer series that really mandates a full blown GIC?
 Your pet platform might cope with it, but I can't see that happening on
 the RPi.

 I don't know, sorry, things are happening too fast and i can't follow 
everything.
 Well, actually it is possible to work without virtual timer at all. Yes, this 
means qemu has to
implement some memory-mapped timer. With HW models like vexpress this is 
already done and works
fine. I even tried to address this:
https://lists.gnu.org/archive/html/qemu-devel/2015-06/msg06627.html, but Peter 
suggested to complete
an API instead.
 I have done this as a proof-of-concept and case study for my project, so i 
want to upstream this in
order not to be lost.
 After all, recent specs say that generic timer can also be memory-mapped. So, 
making KVM working
without both vGIC and vTimer is not a real problem. This patchset addresses 
this scenario too, just
needs some extra bits on vtimer side (ability to init KVM without it).

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


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RE: [PATCH v2 1/3] KVM: arm: Fix NULL pointer dereference if KVM is used without in-kernel irqchip

2015-07-19 Thread Pavel Fedin
 Hello!

 I'd appreciate a better commit log. Which patch broke it, why is that
 necessary.

 It was broken by 662d9715840aef44dcb573b0f9fab9e8319c868a.
 Actually, runtime detection was never implemented. The patch message just says 
that it can be done.
And in order to run KVM on my lame board i had to disable VGIC and VTIMER in 
kernel .config. The
actual breakage happened because without these definitions 
kvm_vgic_map_resources() was just a
do-nothing inline.

 vGIC can perfectly be emulated by userspace. And even generic timer can, with 
some tricks. So i
decided to restore this functionality.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia


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