[PATCH 0/4] KVM: Register cpuhp/syscore callbacks when enabling virt

Sean Christopherson
2024-04-25T23:39:54Z

Register KVM's cpuhp and syscore callbacks when enabling virtualization in
hardware, as the sole purpose of said callbacks is to disable and re-enable
virtualization as needed.

The primary motivation for this series is to simplify dealing with enabling
virtualization for Intel's TDX, which needs to temporarily enable virtualization
when kvm-intek.ko is loaded, i.e. long before the first VM is created.

That said, this is a nice cleanup on its own, assuming I haven't broken
something. By registering the callbacks on-demand, the callbacks themselves
don't need to check kvm_usage_count, because their very existence implies a
non-zero count.

The meat is in patch 3, patches 1 and 2 are tangentially related x86
cleanups, patch 4 renames helpers to further pave the way for TDX.

Moderately well tested on x86, though I haven't (yet) done due dilegence on
the suspend/resume and cphup paths. I ran selftests on arm64 and nothing
exploded.

Sean Christopherson (4):
x86/reboot: Unconditionally define cpu_emergency_virt_cb typedef
KVM: x86: Register emergency virt callback in common code, via
kvm_x86_ops
KVM: Register cpuhp and syscore callbacks when enabling hardware
KVM: Rename functions related to enabling virtualization hardware

arch/x86/include/asm/kvm_host.h | 3 +
arch/x86/include/asm/reboot.h | 2 +-
arch/x86/kvm/svm/svm.c | 5 +-
arch/x86/kvm/vmx/main.c | 2 +
arch/x86/kvm/vmx/vmx.c | 6 +-
arch/x86/kvm/vmx/x86_ops.h | 1 +
arch/x86/kvm/x86.c | 5 +
virt/kvm/kvm_main.c | 186 +++++++++++---------------------
8 files changed, 78 insertions(+), 132 deletions(-)

base-commit: 7b076c6a308ec5bce9fc96e2935443ed228b9148
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2.44.0.769.g3c40516874-goog