[RFC PATCH 0/5] KVM: arm64: Use TTBR1_EL2 for hVHE runtime mappings

[Aneesh Kumar K.V (Arm)]

hVHE currently disables TTBR1_EL2 and places both the identity mapping
and the hyp runtime mappings in TTBR0_EL2. As a result, it continues to
use the legacy nVHE virtual-address layout even though hVHE uses the
EL2&0 translation regime and can retain canonical kernel-image addresses.

This series moves the hVHE runtime mappings to TTBR1_EL2 and reserves
TTBR0_EL2 for the identity mapping used during MMU and page-table
transitions. Conventional VHE is unaffected, and nVHE continues to use
the existing TTBR0-only layout, including when protected mode is enabled.

The existing code does not consistently distinguish kernel-image symbols
from linear-map addresses because both currently use the same EL2
address transformation. The first four patches make this distinction
explicit by:

  - adding helpers for kernel-image symbol addresses;
  - splitting the hyp mapping APIs by address type;
  - providing separate symbol and linear VA-to-PA conversions; and
  - clarifying the private hyp VA allocation terminology.

The final patch implements the TTBR1 layout. Hyp symbols retain their
linked kernel-image VAs, while pools, per-CPU regions, SVE state and shared
memory continue to use linear-map addresses. A separate TTBR0 page table
contains the idmap, and both roots are installed during initial EL2 setup
and pKVM finalization.

The resulting layouts are:

  nVHE:
    TTBR0_EL2: idmap and runtime mappings
    TTBR1_EL2: unused

  hVHE:
    TTBR0_EL2: idmap
    TTBR1_EL2: runtime mappings

Cc: Marc Zyngier <maz@xxxxxxxxxx> 
Cc: Oliver Upton <oupton@xxxxxxxxxx>
Cc: Joey Gouly <joey.gouly@xxxxxxx>
Cc: Steffen Eiden <seiden@xxxxxxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Zenghui Yu <yuzenghui@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>

Aneesh Kumar K.V (Arm) (5):
  KVM: arm64: Make hyp symbol address conversion explicit
  KVM: arm64: Split hyp mapping APIs by address type
  KVM: arm64: Split hyp VA-to-PA conversion by address type
  KVM: arm64: Rename the hyp private VA allocation base
  KVM: arm64: Use TTBR1_EL2 for hVHE runtime mappings

 arch/arm64/include/asm/kvm_asm.h         |  13 +--
 arch/arm64/include/asm/kvm_host.h        |   2 +
 arch/arm64/include/asm/kvm_hyp.h         |   4 +-
 arch/arm64/include/asm/kvm_mmu.h         |  89 ++++++++++++++--
 arch/arm64/include/asm/kvm_pgtable.h     |  27 +++++
 arch/arm64/include/asm/kvm_pkvm.h        |   3 +
 arch/arm64/kernel/asm-offsets.c          |   5 +-
 arch/arm64/kvm/arm.c                     |  92 +++++++++-------
 arch/arm64/kvm/hyp/include/nvhe/memory.h |  13 +--
 arch/arm64/kvm/hyp/include/nvhe/mm.h     |   9 +-
 arch/arm64/kvm/hyp/nvhe/early_alloc.c    |   1 +
 arch/arm64/kvm/hyp/nvhe/events.c         |   2 +-
 arch/arm64/kvm/hyp/nvhe/host.S           |   4 +-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S       |  29 ++++-
 arch/arm64/kvm/hyp/nvhe/mem_protect.c    |  30 +++---
 arch/arm64/kvm/hyp/nvhe/mm.c             | 110 +++++++++++++------
 arch/arm64/kvm/hyp/nvhe/psci-relay.c     |  12 +--
 arch/arm64/kvm/hyp/nvhe/setup.c          |  55 +++++++---
 arch/arm64/kvm/hyp/pgtable.c             |  62 ++++++++++-
 arch/arm64/kvm/hyp_trace.c               |   2 +-
 arch/arm64/kvm/mmu.c                     | 128 ++++++++++++++++-------
 arch/arm64/kvm/pkvm.c                    |   3 +
 arch/arm64/kvm/va_layout.c               |  32 +++++-
 23 files changed, 546 insertions(+), 181 deletions(-)


base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
-- 
2.43.0