[PATCH v4 00/19] KVM GICv3 emulation

Andre Przywara andre.przywara at arm.com
Fri Nov 14 02:07:44 PST 2014

This is version 4 of the GICv3 guest emulation series.

As the previous series, this is based on v3.18-rc2. I didn't bother to
update this to keep it diff-able with v3 of the patch series.

I addressed most of the comments from Christoffer's last review round
(mange tak!). There were numerous changes, though mostly reworking and
style changes. To ease spotting them I updated the kvm-gicv3/v3 branch
in the repo mentioned below to carry all the delta patches. Those
patches are just for reference to see what has changed between
v3 and v4. For review and all other purposes please use the v4 branch.

For an changelog summary see below, also each patch carries a
changelog now.
Patch 02, 04, 06, 07, 09, 10, 11 have had no code changes compared to
their previous counterparts.
The (v3) patch 06 is gone now, the new patch 14 has changed dramatically
and a new patch (16/19) has been added.

I quickly tested this version with a GICv3 capable fast model in all
endianness modes (LE guest on LE host, BE on LE, LE on BE, BE on BE).
Both a GICv2 and a GICv3 guest were booted in all four combinations.
In contrast to the v3 commit message, cross-endianness was working
fine already with the previous patch series.

A git repo hosting all these patches lives in the kvm-gicv3/v4 branch

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 Linux-3.17 Marc introduced 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)
- Only Group1 interrupts support

The first patches actually refactor the current VGIC code to make
room for a different VGIC model to be dropped in with Patch 16.
The remaining patches connect the new model to the kernel backend and
the userland facing code.

The series goes on top of v3.18-rc2.
The necessary patches for kvmtool to enable the guest's GICv3 have
been posted here before [1], an updated version will follow soon.

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 regressions).

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/010086.html

Changes v3 ... v4:
* bug-fix in handling GICv3 redistributor CFG register
* move set/get_lr from gic_vm_ops back to vgic_ops (get rid of v3 06/19)
* getting rid of init_emul() at all
* rework guest GIC model initialization
* use non-atomic bit-set and bit-clear functions
* split up handle_mmio_misc* into multiple functions
* refine handling of some reserved registers
* use symbolic names for ICC_SGI1R_EL1 register fields (new patch 16/19)
* move private parameter from MMIO accessors to struct kvm_mmio_exit
* added documentation of new GICv3 guest device
* added lots of comments
* some renaming of identifiers
* minor changes in style and code flow of various functions

Changes v2 ... v3:
* rebase to v3.18-rc2
* adapt to new kvm_register_device() function
* split up vm_ops patch and the GICv2 split-off patch to ease review
* various smaller changes due to Christoffer's review
* fix compilation for arm
* remove support for trapping SGI sysreg accesses on arm hosts

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 (19):
  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: move kvm_register_device_ops() into vGIC probing
  arm/arm64: KVM: dont rely on a valid GICH base address
  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: add vgic.h header file
  arm/arm64: KVM: split GICv2 specific emulation code from vgic.c
  arm/arm64: KVM: add opaque private pointer to MMIO data
  arm/arm64: KVM: add virtual GICv3 distributor emulation
  arm64: GICv3: introduce symbolic names for GICv3 ICC_SGI1R_EL1 fields
  arm64: KVM: add SGI generation register emulation
  arm/arm64: KVM: enable kernel side of GICv3 emulation
  arm/arm64: KVM: allow userland to request a virtual GICv3

 Documentation/virtual/kvm/devices/arm-vgic.txt |   21 +-
 arch/arm/include/asm/kvm_emulate.h             |    5 +-
 arch/arm/include/asm/kvm_host.h                |    3 +
 arch/arm/include/asm/kvm_mmio.h                |    1 +
 arch/arm/kvm/Makefile                          |    1 +
 arch/arm/kvm/arm.c                             |   23 +-
 arch/arm/kvm/psci.c                            |   17 +-
 arch/arm64/include/asm/kvm_emulate.h           |    5 +-
 arch/arm64/include/asm/kvm_host.h              |    5 +
 arch/arm64/include/asm/kvm_mmio.h              |    1 +
 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 +-
 drivers/irqchip/irq-gic-v3.c                   |   14 +-
 include/kvm/arm_vgic.h                         |   34 +-
 include/linux/irqchip/arm-gic-v3.h             |   44 +
 include/linux/kvm_host.h                       |    2 +
 include/uapi/linux/kvm.h                       |    2 +
 virt/kvm/arm/vgic-v2-emul.c                    |  805 ++++++++++++++++++
 virt/kvm/arm/vgic-v2.c                         |    3 +
 virt/kvm/arm/vgic-v3-emul.c                    | 1020 +++++++++++++++++++++++
 virt/kvm/arm/vgic-v3.c                         |   89 +-
 virt/kvm/arm/vgic.c                            | 1065 ++++++------------------
 virt/kvm/arm/vgic.h                            |  122 +++
 26 files changed, 2469 insertions(+), 874 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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