[PATCH v2 0/3] kvmtool: Limit IPA space to what is actually required

[Marc Zyngier <maz@kernel.org>]

KVM hacking on the Apple M1 SoC has shown that kvmtool (and other
VMMs) make pretty poor use of the IPA space parameter (read: do not
use it and just pass 0). This results in a guest that cannot boot
(recent kernels will just send the VMM packing), and in general means
we don't benefit from smaller page tables at stage-2.

This series does three things:
- It switches kvmtool away from the default 40bit, allowing large VMs
  to be created (I have booted a 4TB VM)
- It reduces the requested IPA space to be as small as possible
- It tells the user why the VM cannot boot when the IPA space required
  exceeds that of the HW

With these changes, kvmtool is able to spawn a VM on IPA-challenged
systems such the Apple M1.

* From v1:
  - Use KVM_VM_TYPE_ARM_IPA_SIZE()
  - Rebased on a recent HEAD

Marc Zyngier (3):
  kvmtool: Abstract KVM_VM_TYPE into a weak function
  kvmtool: arm64: Use the maximum supported IPA size when creating the
    VM
  kvmtool: arm64: Configure VM with the minimal required IPA space

 arm/aarch64/include/kvm/kvm-arch.h | 19 ++++++++++++++---
 arm/aarch64/kvm.c                  | 33 ++++++++++++++++++++++++++++++
 include/kvm/kvm.h                  |  1 +
 kvm.c                              |  7 ++++++-
 4 files changed, 56 insertions(+), 4 deletions(-)

-- 
2.30.2

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