[v4,00/18] KVM: arm64: Non-protected guest stage-2 support for pKVM

Message

Quentin Perret Dec. 18, 2024, 7:40 p.m. UTC

Hi all,

This is the v4 of the series adding support for non-protected guests
stage-2 to pKVM. Please refer to v1 for all the context:

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

Please note that in its current form, this series has two main
limitations that will be addressed separately:

 - We don't support mapping devices into guests: this requires
   additional hypervisor support for tracking the 'state' of devices.
   No device assignment until then.

 - Stage-2 mappings are forced to page-granularity even when backed by a
   huge page for the sake of simplicity of this series. I'm only aiming
   at functional parity-ish (from userspace's PoV) for now, support for
   HP can be added on top later as a perf improvement.

The series is organized as follows:

 - Patches 01 to 04 move the host ownership state tracking from the
   host's stage-2 page-table to the hypervisor's vmemmap. This avoids
   fragmenting the host stage-2 for shared pages, which is only needed
   to store an annotation in the SW bits of the corresponding PTE. All
   pages mapped into non-protected guests are shared from pKVM's PoV,
   so the cost of stage-2 fragmentation will increase massively as we
   start tracking that at EL2. Note that these patches also help with
   the existing sharing for e.g. FF-A, so they could possibly be merged
   separately from the rest of the series.

 - Patches 05 to 07 implement a minor refactoring of the pgtable code to
   ease the integration of the pKVM MMU later on.

 - Patches 08 to 16 introduce all the infrastructure needed on the pKVM
   side for handling guest stage-2 page-tables at EL2.

 - Patches 17 and 18 plumb the newly introduced pKVM support into
   KVM/arm64.

Patches based on 6.13-rc3, tested on Pixel 6 and Qemu.

Changes in v4:
 - Collected Tested-by and Reviewed-by tags
 - Reworked KVM_S2_PGT to help ctags/grepping kvm_pgtable_* functions
 - Minor cleanups throughout

Changes in v3:
 - Rebased on 6.13-rc3
 - Applied Marc's rework of the for_each_mapping_in_range() macro mess
 - Removed mappings_lock in favor the mmu_lock
 - Dropped BUG_ON() from pkvm_mkstate()
 - Renamed range_is_allowed_memory() and clarified the comment inside it
 - Explicitly bail out when using host_stage2_set_owner_locked() on
   non-memory regions
 - Check PKVM_NOPAGE state as an equality rather than a bitwise
   operator
 - Reworked __pkvm_host_share_guest() to return -EPERM in case of
   illegal multi-sharing
 - Added get_np_pkvm_hyp_vm() to simplify HVC error handling in
   hyp-main.c
 - Cosmetic changes and improved coding consitency thoughout the series

Changes in v2:
 - Rebased on 6.13-rc1 (small conflicts with commit 2362506f7cff ("KVM:
   arm64: Don't mark "struct page" accessed when making SPTE young") in
   particular)
 - Fixed kerneldoc breakage for __unmap_stage2_range()
 - Fixed pkvm_pgtable_test_clear_young() to use correct HVC
 - Folded guest_get_valid_pte() into __check_host_unshare_guest() for
   clarity

Thanks,
Quentin

Marc Zyngier (1):
  KVM: arm64: Introduce __pkvm_vcpu_{load,put}()

Quentin Perret (17):
  KVM: arm64: Change the layout of enum pkvm_page_state
  KVM: arm64: Move enum pkvm_page_state to memory.h
  KVM: arm64: Make hyp_page::order a u8
  KVM: arm64: Move host page ownership tracking to the hyp vmemmap
  KVM: arm64: Pass walk flags to kvm_pgtable_stage2_mkyoung
  KVM: arm64: Pass walk flags to kvm_pgtable_stage2_relax_perms
  KVM: arm64: Make kvm_pgtable_stage2_init() a static inline function
  KVM: arm64: Add {get,put}_pkvm_hyp_vm() helpers
  KVM: arm64: Introduce __pkvm_host_share_guest()
  KVM: arm64: Introduce __pkvm_host_unshare_guest()
  KVM: arm64: Introduce __pkvm_host_relax_guest_perms()
  KVM: arm64: Introduce __pkvm_host_wrprotect_guest()
  KVM: arm64: Introduce __pkvm_host_test_clear_young_guest()
  KVM: arm64: Introduce __pkvm_host_mkyoung_guest()
  KVM: arm64: Introduce __pkvm_tlb_flush_vmid()
  KVM: arm64: Introduce the EL1 pKVM MMU
  KVM: arm64: Plumb the pKVM MMU in KVM

 arch/arm64/include/asm/kvm_asm.h              |   9 +
 arch/arm64/include/asm/kvm_host.h             |   4 +
 arch/arm64/include/asm/kvm_mmu.h              |  16 +
 arch/arm64/include/asm/kvm_pgtable.h          |  38 ++-
 arch/arm64/include/asm/kvm_pkvm.h             |  26 ++
 arch/arm64/kvm/arm.c                          |  23 +-
 arch/arm64/kvm/hyp/include/nvhe/gfp.h         |   6 +-
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  39 +--
 arch/arm64/kvm/hyp/include/nvhe/memory.h      |  50 ++-
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |  16 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            | 201 ++++++++++-
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 320 ++++++++++++++++--
 arch/arm64/kvm/hyp/nvhe/page_alloc.c          |  14 +-
 arch/arm64/kvm/hyp/nvhe/pkvm.c                |  69 ++++
 arch/arm64/kvm/hyp/nvhe/setup.c               |   7 +-
 arch/arm64/kvm/hyp/pgtable.c                  |  13 +-
 arch/arm64/kvm/mmu.c                          |  93 +++--
 arch/arm64/kvm/pkvm.c                         | 201 +++++++++++
 arch/arm64/kvm/vgic/vgic-v3.c                 |   6 +-
 19 files changed, 1006 insertions(+), 145 deletions(-)