To spawn KVM-enabled Virtual Machines on Linux systems, one has to use QEMU, or some other kind of VM monitor in user-space to host the vCPU threads, I/O threads and various other book-keeping/management mechanisms. This is perfectly fine for a large number of reasons and use cases: for instance, running generic VMs, running general purpose Operating systems that need some kind of emulation for legacy boot/hardware etc. What if we wanted to execute a small piece of code as a guest instance, without the involvement of user-space? The KVM functions are already doing what they should: VM and vCPU setup is already part of the kernel, the only missing piece is memory handling. With these series, (a) we expose to the Linux Kernel the bare minimum KVM API functions in order to spawn a guest instance without the intervention of user-space; and (b) we tweak the memory handling code of KVM-related functions to account for another kind of guest, spawned in kernel-space. PATCH #1 exposes the needed stub functions, whereas PATCH #2 introduces the changes in the KVM memory handling code for x86_64 and aarch64. An example of use is provided based on kvmtest.c [https://lwn.net/Articles/658512/] at https://github.com/cloudkernels/kvmmtest Anastassios Nanos (2): KVMM: export needed symbols KVMM: Memory and interface related changes arch/arm64/include/asm/kvm_host.h | 6 ++ arch/arm64/kvm/fpsimd.c | 8 +- arch/arm64/kvm/guest.c | 48 +++++++++++ arch/x86/include/asm/fpu/internal.h | 10 ++- arch/x86/kvm/cpuid.c | 25 ++++++ arch/x86/kvm/emulate.c | 3 +- arch/x86/kvm/vmx/vmx.c | 3 +- arch/x86/kvm/x86.c | 38 ++++++++- include/linux/kvm_host.h | 36 +++++++++ virt/kvm/arm/arm.c | 18 +++++ virt/kvm/arm/mmu.c | 34 +++++--- virt/kvm/async_pf.c | 4 +- virt/kvm/coalesced_mmio.c | 6 ++ virt/kvm/kvm_main.c | 120 ++++++++++++++++++++++------ 14 files changed, 316 insertions(+), 43 deletions(-) -- 2.20.1
