[PATCH v2 0/7] KVM: arm64: Fix handling of host fpsimd/sve state in protected mode

[Fuad Tabba <tabba@google.com>]

Changes since v1 [1]
- Introduced a new helper, cpacr_clear_set(), which abstracts
setting/clearing CPTR_EL2 or CPACR_EL1, depending on the mode
(vhe/nvhe/hvhe) (Oliver)
- Dropped the patch that specializes deactivating fpsimd/sve
traps on guest trap, since the new helper removes the need for
doing that

With the KVM host data rework [2], handling of fpsimd and sve
state in protected mode is done at hyp. For protected VMs, we
don't want to leak any guest state to the host, including whether
a guest has used fpsimd/sve.

To complete the work started with the host data rework, in
regards to protected mode, ensure that the host's fpsimd context
and its sve context are restored on guest exit, since the rework
has hidden the fpsimd/sve state from the host.

This patch series eagerly restores the host fpsimd/sve state on
guest exit when running in protected mode, which happens only if
the guest has used fpsimd/sve. This means that the saving of the
state is lazy, similar to the behavior of KVM in other modes, but
the restoration of the host state is eager.

This series is based on kvmarm-6.10-1 (kvmarm/next). It should
not have any functional effect on modes other than protected mode.

Tested on qemu, with the kernel sve stress tests.

Cheers,
/fuad

[1] https://lore.kernel.org/all/20240517131814.719933-1-tabba@google.com/
[2] https://lore.kernel.org/all/20240322170945.3292593-1-maz@kernel.org/

Fuad Tabba (7):
  KVM: arm64: Reintroduce __sve_save_state
  KVM: arm64: Abstract set/clear of CPTR_EL2 bits behind helper
  KVM: arm64: Specialize handling of host fpsimd state on trap
  KVM: arm64: Store the maximum sve vector length at hyp
  KVM: arm64: Allocate memory at hyp for host sve state in pKVM
  KVM: arm64: Eagerly restore host fpsimd/sve state in pKVM
  KVM: arm64: Consolidate initializing the host data's fpsimd_state/sve
    in pKVM

 arch/arm64/include/asm/kvm_emulate.h    | 34 +++++++++++
 arch/arm64/include/asm/kvm_host.h       | 11 +++-
 arch/arm64/include/asm/kvm_hyp.h        |  2 +
 arch/arm64/include/asm/kvm_pkvm.h       |  9 +++
 arch/arm64/include/uapi/asm/ptrace.h    | 14 +++++
 arch/arm64/kvm/arm.c                    | 75 +++++++++++++++++++++++++
 arch/arm64/kvm/hyp/fpsimd.S             |  6 ++
 arch/arm64/kvm/hyp/include/hyp/switch.h | 32 ++++++-----
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h  |  1 -
 arch/arm64/kvm/hyp/nvhe/hyp-main.c      | 59 ++++++++++++++++---
 arch/arm64/kvm/hyp/nvhe/pkvm.c          | 15 ++---
 arch/arm64/kvm/hyp/nvhe/setup.c         | 25 ++++++++-
 arch/arm64/kvm/hyp/nvhe/switch.c        | 19 +++++++
 arch/arm64/kvm/hyp/vhe/switch.c         |  5 ++
 arch/arm64/kvm/reset.c                  |  2 +
 15 files changed, 273 insertions(+), 36 deletions(-)


base-commit: eaa46a28d59655aa89a8fb885affa6fc0de44376
-- 
2.45.0.215.g3402c0e53f-goog