[PATCH v4 00/20] irqchip/gic-v4: GICv4.1 architecture support

[Marc Zyngier <maz@kernel.org>]

This (now shorter) series expands the existing GICv4 support to deal
with the new GICv4.1 architecture, which comes with a set of major
improvements compared to v4.0:

- One architectural doorbell per vcpu, instead of one doorbell per VLPI

- Doorbell entirely managed by the HW, with an "at most once" delivery
  guarantee per non-residency phase and only when requested by the
  hypervisor

- A shared memory scheme between ITSs and redistributors, allowing for an
  optimised residency sequence (the use of VMOVP becomes less frequent)

- Support for direct virtual SGI delivery (the injection path still involves
  the hypervisor), at the cost of losing the active state on SGIs. It
  shouldn't be a big deal, but some guest operating systems might notice
  (Linux definitely won't care).

On the other hand, public documentation is not available yet, so that's a
bit annoying...

The series is roughly organised in 3 parts:

(1) v4.1 doorbell management
(2) Virtual SGI support
(3) Plumbing of virtual SGIs in KVM

Notes:

  - The whole thing is tested on a FVP model, which can be obtained
    free of charge on ARM's developer website. It requires you to
    create an account, unfortunately... You'll need a fix for the
    devicetree that is in the kernel tree (should be merged before
    the 5.6 release).

  - This series has uncovered a behaviour that looks like a HW bug on
    the Cavium ThunderX (aka TX1) platform. I'd very much welcome some
    clarification from the Marvell/Cavium folks on Cc, as well as an
    official erratum number if this happens to be an actual bug.

    [v3 update]
    People have ignored for two months now, and it is fairly obvious
    that support for this machine is slowly bit-rotting. Maybe I'll
    drop the patch and instead start the process of removing all TX1
    support from the kernel (we'd certainly be better off without it).

    [v4 update]
    TX1 is now broken in mainline, and nobody cares. Make of this what
    you want.

* From v3 [3]:
  - Rebased on v5.6-rc1
  - Considerably smaller thanks to the initial patches being merged
  - Small bug fix after the v5.6 merge window

* From v2 [2]:
  - Another bunch of fixes thanks to Zenghui Yu's very careful review
  - HW-accelerated SGIs are now optional thanks to new architected
    discovery/selection bits exposed by KVM and used by the guest kernel
  - Rebased on v5.5-rc2

* From v1 [1]:
  - A bunch of minor reworks after Zenghui Yu's review
  - A workaround for what looks like a new and unexpected TX1 bug
  - A subtle reorder of the series so that some patches can go in early

[1] https://lore.kernel.org/lkml/20190923182606.32100-1-maz@kernel.org/
[2] https://lore.kernel.org/lkml/20191027144234.8395-1-maz@kernel.org/
[3] https://lore.kernel.org/r/20191224111055.11836-1-maz@kernel.org/

Marc Zyngier (20):
  irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors
  irqchip/gic-v3: Use SGIs without active state if offered
  irqchip/gic-v4.1: Advertise support v4.1 to KVM
  irqchip/gic-v4.1: Map the ITS SGIR register page
  irqchip/gic-v4.1: Plumb skeletal VSGI irqchip
  irqchip/gic-v4.1: Add initial SGI configuration
  irqchip/gic-v4.1: Plumb mask/unmask SGI callbacks
  irqchip/gic-v4.1: Plumb get/set_irqchip_state SGI callbacks
  irqchip/gic-v4.1: Plumb set_vcpu_affinity SGI callbacks
  irqchip/gic-v4.1: Move doorbell management to the GICv4 abstraction
    layer
  irqchip/gic-v4.1: Add VSGI allocation/teardown
  irqchip/gic-v4.1: Add VSGI property setup
  irqchip/gic-v4.1: Eagerly vmap vPEs
  KVM: arm64: GICv4.1: Let doorbells be auto-enabled
  KVM: arm64: GICv4.1: Add direct injection capability to SGI registers
  KVM: arm64: GICv4.1: Allow SGIs to switch between HW and SW interrupts
  KVM: arm64: GICv4.1: Plumb SGI implementation selection in the
    distributor
  KVM: arm64: GICv4.1: Reload VLPI configuration on distributor
    enable/disable
  KVM: arm64: GICv4.1: Allow non-trapping WFI when using HW SGIs
  KVM: arm64: GICv4.1: Expose HW-based SGIs in debugfs

 arch/arm/include/asm/kvm_host.h        |   1 +
 arch/arm64/include/asm/kvm_emulate.h   |   3 +-
 arch/arm64/include/asm/kvm_host.h      |   1 +
 drivers/irqchip/irq-gic-v3-its.c       | 301 ++++++++++++++++++++++++-
 drivers/irqchip/irq-gic-v3.c           |  12 +-
 drivers/irqchip/irq-gic-v4.c           | 134 ++++++++++-
 include/kvm/arm_vgic.h                 |   4 +
 include/linux/irqchip/arm-gic-common.h |   2 +
 include/linux/irqchip/arm-gic-v3.h     |  19 +-
 include/linux/irqchip/arm-gic-v4.h     |  20 +-
 virt/kvm/arm/arm.c                     |   8 +
 virt/kvm/arm/vgic/vgic-debug.c         |  14 +-
 virt/kvm/arm/vgic/vgic-mmio-v3.c       |  68 +++++-
 virt/kvm/arm/vgic/vgic-mmio.c          |  88 +++++++-
 virt/kvm/arm/vgic/vgic-v3.c            |   6 +-
 virt/kvm/arm/vgic/vgic-v4.c            | 139 ++++++++++--
 virt/kvm/arm/vgic/vgic.h               |   1 +
 17 files changed, 763 insertions(+), 58 deletions(-)

-- 
2.20.1