[PATCH v2 00/15] KVM GICv3 emulation

Andre Przywara andre.przywara at arm.com
Thu Aug 21 06:06:41 PDT 2014

This is an updated version of the GICv3 guest emulation series.
Compared to v1[1] it has been rebased on v3.17-rc1 (with quite some
conflict resolutions done by MarcZ) and contains minor fixes
(partially triggered by comments on the list, partially due to code
review caused by the rebase). Also there is a new patch (09/15) with
some refactoring to make the big split patch (10/15) smaller.
This big patch contains now an elaborate commit message to detail
the code move, as the diff isn't always obvious here. This part
should be considered for removal from the patch on committing it.

A git repo hosting all these patches lives in the kvm-gicv3/v2 branch
of: http://www.linux-arm.org/git?p=linux-ap.git

GICv3 is the ARM generic interrupt controller designed to overcome
some limits of the prevalent GICv2. Most notably it lifts the 8-CPU
limit. Though with recent patches from Marc there is support for
hosts to use a GICv3, the CPU limitation still applies to KVM guests,
since the current code emulates a GICv2 only.
Also, GICv2 backward compatibility being optional in GICv3, a number
of systems won't be able to run GICv2 guests.

This patch series provides code to emulate a GICv3 distributor and
redistributor for any KVM guest. It requires a GICv3 in the host to
work. With those patches one can run guests efficiently on any GICv3
host. It has the following features:
- Affinity routing (support for up to 255 VCPUs, more possible)
- System registers (as opposed to MMIO access)
- No ITS
- No priority support (as the GICv2 emulation)
- No save / restore support so far (will be added soon)

The first 11 patches actually refactor the current VGIC code to make
room for a different VGIC model to be dropped in with Patch 12/15.
The remaining patches connect the new model to the kernel backend and
the userland facing code.

The series goes on top of v3.17-rc1 and Marc's vgic-dyn series[2].
The necessary patches for kvmtool to enable the guest's GICv3 have
been posted here before [3], an updated version will follow as soon
as the kvmtools tree has been updated.

There was some testing on the fast model with some I/O and interrupt
affinity shuffling in a Linux guest with a varying number of VCPUs as
well as some testing on a Juno board (GICv2 only, to spot

Please review and test.
I would be grateful for people to test for GICv2 regressions also
(so on a GICv2 host with current kvmtool/qemu), as there is quite
some refactoring on that front.

Much of the code was inspired by MarcZ, also kudos to him for doing
the rather painful rebase on top of v3.17-rc1.


[1] https://lists.cs.columbia.edu/pipermail/kvmarm/2014-June/010060.html
[2] https://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/vgic-dyn
[3] https://lists.cs.columbia.edu/pipermail/kvmarm/2014-June/010086.html

Changes v1 ... v2:
* rebase to v3.17-rc1, caused quite some changes to the init code
* new 9/15 patch to make 10/15 smaller
* fix wrongly ordered cp15 register trap entry (MarcZ)
* fix SGI broadcast (thanks to wanghaibin for spotting)
* fix broken bailout path in kvm_vgic_create (wanghaibin)
* check return value of init_emulation_ops() (wanghaibin)
* fix return value check in vgic_[sg]et_attr()
* add header inclusion guards
* remove double definition of VCPU_NOT_ALLOCATED
* some code move-around
* whitespace fixes

Andre Przywara (15):
  arm/arm64: KVM: rework MPIDR assignment and add accessors
  arm/arm64: KVM: pass down user space provided GIC type into vGIC code
  arm/arm64: KVM: refactor vgic_handle_mmio() function
  arm/arm64: KVM: wrap 64 bit MMIO accesses with two 32 bit ones
  arm/arm64: KVM: introduce per-VM ops
  arm/arm64: KVM: make the maximum number of vCPUs a per-VM value
  arm/arm64: KVM: make the value of ICC_SRE_EL1 a per-VM variable
  arm/arm64: KVM: refactor MMIO accessors
  arm/arm64: KVM: refactor/wrap vgic_set/get_attr()
  arm/arm64: KVM: split GICv2 specific emulation code from vgic.c
  arm/arm64: KVM: add opaque private pointer to MMIO accessors
  arm/arm64: KVM: add virtual GICv3 distributor emulation
  arm/arm64: KVM: add SGI system register trapping
  arm/arm64: KVM: enable kernel side of GICv3 emulation
  arm/arm64: KVM: allow userland to request a virtual GICv3

 arch/arm/include/asm/kvm_emulate.h   |    2 +-
 arch/arm/include/asm/kvm_host.h      |    3 +
 arch/arm/kvm/Makefile                |    1 +
 arch/arm/kvm/arm.c                   |   23 +-
 arch/arm/kvm/coproc.c                |   19 +
 arch/arm/kvm/psci.c                  |   15 +-
 arch/arm64/include/asm/kvm_emulate.h |    3 +-
 arch/arm64/include/asm/kvm_host.h    |    5 +
 arch/arm64/include/uapi/asm/kvm.h    |    7 +
 arch/arm64/kernel/asm-offsets.c      |    1 +
 arch/arm64/kvm/Makefile              |    2 +
 arch/arm64/kvm/sys_regs.c            |   37 +-
 arch/arm64/kvm/vgic-v3-switch.S      |   14 +-
 include/kvm/arm_vgic.h               |   38 +-
 include/linux/irqchip/arm-gic-v3.h   |   26 +
 include/linux/kvm_host.h             |    1 +
 include/uapi/linux/kvm.h             |    1 +
 virt/kvm/arm/vgic-v2-emul.c          |  803 +++++++++++++++++++++++++++
 virt/kvm/arm/vgic-v2.c               |   22 +-
 virt/kvm/arm/vgic-v3-emul.c          |  899 ++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic-v3.c               |  187 +++++--
 virt/kvm/arm/vgic.c                  |  992 +++++++---------------------------
 virt/kvm/arm/vgic.h                  |  126 +++++
 virt/kvm/kvm_main.c                  |    3 +
 24 files changed, 2361 insertions(+), 869 deletions(-)
 create mode 100644 virt/kvm/arm/vgic-v2-emul.c
 create mode 100644 virt/kvm/arm/vgic-v3-emul.c
 create mode 100644 virt/kvm/arm/vgic.h


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