KVM: arm64: Enable SVE support on nVHE systems

This series enables SVE support for KVM on nVHE hardware (or more likely, software models), and is an alternative to Daniel's patch[1] which has gone through 3 versions, but still has a number of issues.

Instead of waiting for things to happen, I decided to try and see what I could come up with.

The SVE save/restore is modelled after the SVE VHE flow, itself closely following the FPSIMD flow:

- the guest traps to EL2 on first SVE access, and will not trap anymore until vcpu_put()

- ZCR_EL2 stays constant as long as the guest has SVE enabled

- once back on the host side, ZCR_EL2 is restored to its default value on first SVE access

Most of this series only repaints things so that VHE and nVHE look as similar as possible, the ZCR_EL2 management being the most visible exception. This results in a bunch of preparatory patches that aim at making the code slightly more readable.

This has been tested on a FVP model with both VHE/nVHE configurations using the string tests included with the "optimized-routines" library[2].

Patches against 5.12-rc2.

* From v1 [3]:
- Fixed __sve_save_state SYM_FUNC_END label
- Turned the ZCR_EL2 reset hypercall into a host trap
- Fixed SVE state mapping size
- Correctly mask RES0 bits from ZCR_ELx
- Introduced sve_cond_update_zcr_vq() as a ZCR_ELx update helper
- Renamed vcpu_sve_vq() to vcpu_sve_max_vq()
- Collected Acks from Will

[1] https://lore.kernel.org/r/[email protected]
[2] https://github.com/ARM-software/optimized-routines
[3] https://lore.kernel.org/r/[email protected]

Daniel Kiss (1):
KVM: arm64: Enable SVE support for nVHE

Marc Zyngier (10):
KVM: arm64: Provide KVM's own save/restore SVE primitives
KVM: arm64: Use {read,write}_sysreg_el1 to access ZCR_EL1
KVM: arm64: Let vcpu_sve_pffr() handle HYP VAs
KVM: arm64: Introduce vcpu_sve_vq() helper
arm64: sve: Provide a conditional update accessor for ZCR_ELx
KVM: arm64: Rework SVE host-save/guest-restore
KVM: arm64: Map SVE context at EL2 when available
KVM: arm64: Save guest's ZCR_EL1 before saving the FPSIMD state
KVM: arm64: Trap host SVE accesses when the FPSIMD state is dirty
KVM: arm64: Save/restore SVE state for nVHE

 arch/arm64/Kconfig                      |  7 ---
 arch/arm64/include/asm/fpsimd.h         |  9 +++
 arch/arm64/include/asm/fpsimdmacros.h   | 10 +++-
 arch/arm64/include/asm/kvm_host.h       | 21 ++-----
 arch/arm64/include/asm/kvm_hyp.h        |  2 +
 arch/arm64/kvm/arm.c                    |  5 --
 arch/arm64/kvm/fpsimd.c                 | 26 +++++++--
 arch/arm64/kvm/guest.c                  |  6 +-
 arch/arm64/kvm/hyp/fpsimd.S             | 10 ++++
 arch/arm64/kvm/hyp/include/hyp/switch.h | 77 ++++++++++++-------------
 arch/arm64/kvm/hyp/nvhe/hyp-main.c      |  4 ++
 arch/arm64/kvm/hyp/nvhe/switch.c        | 13 +++--
 arch/arm64/kvm/reset.c                  |  4 --
 13 files changed, 109 insertions(+), 85 deletions(-)

2.29.2

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