Re: [PATCH 00/14] KVM: PPC: Book3S HV: PCI Passthrough Interrupt Optimizations

["Suresh E. Warrier" <warrier@linux.vnet.ibm.com>]

On 02/26/2016 12:40 PM, Suresh Warrier wrote:
> This patch set adds support for handling interrupts for PCI adapters
> entirely in the guest under the right conditions. When an interrupt
> is received by KVM in real mode, if the interrupt is from a PCI
> passthrough adapter owned by the guest, KVM will update the virtual
> ICP for the VCPU that is the target of the interrupt entirely in
> real mode and generate the virtual interrupt. If the VCPU is not
> running in the guest, it will wake up the VCPU.  It will also update
> the affinity of the interrupt to directly target the CPU (core)
> where this VCPU is being scheduled as an optimization. 
> 
> KVM needs the mapping between hardware interrupt numbers in the host
> to the virtual hardware interrupt (GSI) that needs to get injected
> into the guest. This patch set takes advantage of the IRQ bypass
> manager feature to create this mapping. For now, we allocate and
> manage a separate mapping structure per VM.
> 
> Although a mapping is created for every passthrough IRQ requested
> in the guest, we also maintain a cache of mappings that is used to
> speed up search. For now, KVM real mode code only looks in the cache for
> a mapping. If no mapping is found, we fall back on the usual interrupt
> routing mechanism - switch back to host and run the VFIO interrupt
> handler.
> 
> This is based on 4.5-rc1 plus the patch set in
> http://www.spinics.net/lists/kvm-ppc/msg11131.html since it has
> dependencies on vmalloc_to_phys() being public.
> 
> Suresh Warrier (14):
>   powerpc: Add simple cache inhibited MMIO accessors
>   KVM: PPC: Book3S HV: Convert kvmppc_read_intr to a C function
>   KVM: PPC: select IRQ_BYPASS_MANAGER
>   KVM: PPC: Book3S HV: Introduce kvmppc_passthru_irqmap
>   KVM: PPC: Book3S HV: Enable IRQ bypass
>   KVM: PPC: Book3S HV: Caching for passthrough IRQ map
>   KVM: PPC: Book3S HV: Handle passthrough interrupts in guest
>   KVM: PPC: Book3S HV: Complete passthrough interrupt in host
>   KVM: PPC: Book3S HV: Enable KVM real mode handling of passthrough IRQs
>   KVM: PPC: Book3S HV: Dump irqmap in debugfs
>   KVM: PPC: Book3S HV: Tunable to disable KVM IRQ bypass
>   KVM: PPC: Book3S HV: Update irq stats for IRQs handled in real mode
>   KVM: PPC: Book3S HV: Change affinity for passthrough IRQ
>   KVM: PPC: Book3S HV: Counters for passthrough IRQ stats
> 
>  arch/powerpc/include/asm/io.h             |  28 +++
>  arch/powerpc/include/asm/kvm_asm.h        |  10 +
>  arch/powerpc/include/asm/kvm_book3s.h     |   1 +
>  arch/powerpc/include/asm/kvm_host.h       |  25 +++
>  arch/powerpc/include/asm/kvm_ppc.h        |  28 +++
>  arch/powerpc/include/asm/pnv-pci.h        |   1 +
>  arch/powerpc/kvm/Kconfig                  |   2 +
>  arch/powerpc/kvm/book3s.c                 |  45 +++++
>  arch/powerpc/kvm/book3s_hv.c              | 318 +++++++++++++++++++++++++++++-
>  arch/powerpc/kvm/book3s_hv_builtin.c      | 157 +++++++++++++++
>  arch/powerpc/kvm/book3s_hv_rm_xics.c      | 181 +++++++++++++++++
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 226 ++++++++++++---------
>  arch/powerpc/kvm/book3s_xics.c            |  68 ++++++-
>  arch/powerpc/kvm/book3s_xics.h            |   3 +
>  arch/powerpc/platforms/powernv/pci-ioda.c |  14 +-
>  15 files changed, 1013 insertions(+), 94 deletions(-)
>