It will be very useful for user space if it has a method for specifying KVM ARM/ARM64 to give a VCPU with target type suitable to underlying host but with particular set of features.
In other words, user space might not be interested in having a particular target type for VCPU but it will certainely want particular set of features in the VCPU.
The patch tries to implement above described method of specifying VCPU target CPU=Host from user space by extending the KVM_ARM_VCPU_INIT ioctl and having a dummy target KVM_ARM_TARGET_HOST which means Target CPU same as (or suitable to) underlying host.
This change in KVM_ARM_VCPU_INIT ioctl is backward compatible to its current semantics hence does not break user space. The only difference is that it will now update the struct kvm_vcpu_init instance (passed by user space) with targer type and features of the VCPU that will be emulated by KVM ARM/ARM64.
Anup Patel (3): ARM: KVM: Implement target CPU=Host ARM64: KVM: Implement target CPU=Host KVM: ARM: Update documentation for KVM_ARM_VCPU_INIT ioctl
Documentation/virtual/kvm/api.txt | 5 ++++- arch/arm/include/asm/kvm_host.h | 2 +- arch/arm/include/uapi/asm/kvm.h | 1 + arch/arm/kvm/arm.c | 9 ++++++++- arch/arm/kvm/guest.c | 11 +++++++++-- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/include/uapi/asm/kvm.h | 2 +- arch/arm64/kvm/guest.c | 10 ++++++++-- 8 files changed, 33 insertions(+), 9 deletions(-)