[RFC PATCH 00/13] KVM: planes: Userspace API

[David Woodhouse]

From: David Woodhouse <dwmw@xxxxxxxxxxxx>

The VSM work¹ drives planes from userspace, which takes a little
more API than the planes series² itself provides: an explicit
userspace opt-in (enabling KVM_CAP_PLANES with the plane count,
before any vCPU is created), KVM_GET/SET_PLANE_RUN_STATE vCPU
ioctls, and the mechanics to go with them — per-plane requests
fanned out to the twin vCPUs, XCR0 shared across twins (with every
twin's fpstate sized for the dynamic xfeatures that allows), and
APICv inhibited while planes are enabled (for now). With selftests,
including Paolo's plane infrastructure tests from the original
planes RFC³, ported forward.

Posted separately from the VSM RFC v2 (to follow) so this part can
be reviewed — or folded — with the rest of the planes series. Based
on that series² with my fixes⁴ applied (including two follow-up
patches on that thread); the whole stack is at ⁵.

¹ https://lore.kernel.org/kvm/20261017122501.610248-1-dwmw2@xxxxxxxxxxxxx/
² https://lore.kernel.org/kvm/20260608144252.351443-1-joro@xxxxxxxxxx/
³ https://lore.kernel.org/all/20250401161106.790710-29-pbonzini@xxxxxxxxxx/
⁴ https://lore.kernel.org/kvm/20261111222911.477-1-dwmw2@xxxxxxxxxxxxx/
⁵ https://git.infradead.org/?p=users/dwmw2/linux.git;a=shortlog;h=refs/heads/vsm2/planes-uapi

David Woodhouse (12):
  KVM: x86: Let userspace opt in to multiple planes with KVM_CAP_PLANES
  KVM: selftests: Add x86 planes lifecycle test
  KVM: Add KVM_GET/SET_PLANE_RUN_STATE vCPU ioctls
  KVM: selftests: Cover plane run-state ioctls in planes_test
  KVM: planes: Fan out per-plane requests to twin vCPUs
  KVM: x86: Inhibit APICv when VM planes are enabled
  KVM: planes: Enlarge every twin's fpstate for dynamic xfeatures
  KVM: x86: Let userspace choose state for plane twins to share
  KVM: planes: Let plane twins share XCR0
  KVM: planes: Let plane twins share DR6
  KVM: selftests: Check CPUID handling of plane twins
  KVM: selftests: Cover plane state sharing

Paolo Bonzini (1):
  KVM: selftests: Add VM plane infrastructure and tests

 Documentation/virt/kvm/api.rst                | 129 +++-
 arch/powerpc/kvm/trace.h                      |   3 +-
 arch/x86/include/asm/kvm_host.h               |   8 +-
 arch/x86/include/uapi/asm/kvm.h               |   4 +
 arch/x86/kvm/cpuid.c                          |  25 +-
 arch/x86/kvm/mmu/mmu.c                        |  13 +-
 arch/x86/kvm/regs.c                           |   1 +
 arch/x86/kvm/svm/svm.h                        |   3 +-
 arch/x86/kvm/trace.h                          |   3 +-
 arch/x86/kvm/vmx/main.c                       |   3 +-
 arch/x86/kvm/x86.c                            | 221 ++++++-
 arch/x86/kvm/x86.h                            |  21 +
 include/linux/kvm_host.h                      |  36 +-
 include/uapi/linux/kvm.h                      |   7 +
 tools/testing/selftests/kvm/Makefile.kvm      |   3 +
 .../testing/selftests/kvm/include/kvm_util.h  |  73 +++
 .../selftests/kvm/include/x86/processor.h     |  14 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  74 ++-
 .../testing/selftests/kvm/lib/x86/processor.c |  47 +-
 tools/testing/selftests/kvm/plane_test.c      | 137 ++++
 .../selftests/kvm/x86/plane_x86_test.c        | 331 ++++++++++
 tools/testing/selftests/kvm/x86/planes_test.c | 605 ++++++++++++++++++
 virt/kvm/kvm_main.c                           | 138 +++-
 23 files changed, 1852 insertions(+), 47 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/plane_test.c
 create mode 100644 tools/testing/selftests/kvm/x86/plane_x86_test.c
 create mode 100644 tools/testing/selftests/kvm/x86/planes_test.c

-- 
2.50.1