[v1,00/12] KVM: arm64: Rework guest VM fixed feature handling and trapping in pKVM

Message

Fuad Tabba Nov. 20, 2024, 10:52 a.m. UTC

This patch series redoes how fixed features for protected guests
are specified in pKVM, as well as how trapping is handled based
on the features available for the VM. It also fixes a couple of
existing bugs in the process.

For protected VMs, some features should be trapped if the guest
tries to use them because they are not supported (e.g., SME), or
if they are not enabled for the particular VM (e.g., SVE).

Initially, pKVM took the approach of specifying these features
using macros and grouping their handling by feature id register.
This proved to be difficult to maintain and bug prone. Moreover,
since the nested virt work there is a framework in KVM for
storing feature id register values per vm, as well as how to
handle traps based on these values.

This patch series uses the vm's feature id registers to track the
supported features, a framework similar to nested virt to set the
trap values, and removes the need to store cptr_el2 per vcpu in
favor of setting its value when traps are activated, as VHE mode
does.

The changes should not affect the behavior of non-protected VMs
nor the behavior of VMs outside of protected mode in general.

This patch series is based on kvmarm/next (60ad25e14ab5), since
it requires the patches from the series that fixes initialization
of trap register values in pKVM [1].

Cheers,
/fuad

[1] https://lore.kernel.org/all/[e-mail]/

Fuad Tabba (12):
  KVM: arm64: Consolidate allowed and restricted VM feature checks
  KVM: arm64: Group setting traps for protected VMs by control register
  KVM: arm64: Move checking protected vcpu features to a separate
    function
  KVM: arm64: Use KVM extension checks for allowed protected VM
    capabilities
  KVM: arm64: Initialize feature id registers for protected VMs
  KVM: arm64: Set protected VM traps based on its view of feature
    registers
  KVM: arm64: Rework specifying restricted features for protected VMs
  KVM: arm64: Remove fixed_config.h header
  KVM: arm64: Remove redundant setting of HCR_EL2 trap bit
  KVM: arm64: Calculate cptr_el2 traps on activating traps
  KVM: arm64: Update vcpu state with live value of VBAR_EL1 on injecting
    an exception
  fixup! KVM: arm64: Initialize feature id registers for protected VMs

 arch/arm64/include/asm/kvm_host.h             |   1 -
 arch/arm64/include/asm/kvm_pkvm.h             |  25 ++
 arch/arm64/kvm/arm.c                          |  30 +-
 .../arm64/kvm/hyp/include/nvhe/fixed_config.h | 223 ----------
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |   5 +
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 313 +++++--------
 arch/arm64/kvm/hyp/nvhe/setup.c               |   1 -
 arch/arm64/kvm/hyp/nvhe/switch.c              |  31 +-
 arch/arm64/kvm/hyp/nvhe/sys_regs.c            | 414 ++++++++++--------
 9 files changed, 403 insertions(+), 640 deletions(-)
 delete mode 100644 arch/arm64/kvm/hyp/include/nvhe/fixed_config.h


base-commit: 60ad25e14ab5a4e56c8bf7f7d6846eacb9cd53df