Re: [PATCH v2 1/2] KVM: PPC: e500mc: Add support for single threaded vcpus on e6500 core

[Alexander Graf <agraf@suse.de>]

On 01.09.14 11:01, Mihai Caraman wrote:
> ePAPR represents hardware threads as cpu node properties in device tree.
> So with existing QEMU, hardware threads are simply exposed as vcpus with
> one hardware thread.
> 
> The e6500 core shares TLBs between hardware threads. Without tlb write
> conditional instruction, the Linux kernel uses per core mechanisms to
> protect against duplicate TLB entries.
> 
> The guest is unable to detect real siblings threads, so it can't use the
> TLB protection mechanism. An alternative solution is to use the hypervisor
> to allocate different lpids to guest's vcpus that runs simultaneous on real
> siblings threads. On systems with two threads per core this patch halves
> the size of the lpid pool that the allocator sees and use two lpids per VM.
> Use even numbers to speedup vcpu lpid computation with consecutive lpids
> per VM: vm1 will use lpids 2 and 3, vm2 lpids 4 and 5, and so on.
> 
> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>

Thanks, applied both to kvm-ppc-queue.


Alex