Re: [PATCH 09/10] KVM: arm64: Save/restore SVE state for nVHE

Implement the SVE save/restore for nVHE, following a similar
logic to that of the VHE implementation:

- the SVE state is switched on trap from EL1 to EL2

- no further changes to ZCR_EL2 occur as long as the guest isn't
  preempted or exit to userspace

- on vcpu_put(), ZCR_EL2 is reset to its default value, and ZCR_EL1
  restored to the default guest value

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/fpsimd.c                 | 15 ++++++++--
 arch/arm64/kvm/hyp/include/hyp/switch.h | 37 +++++++++----------------
 arch/arm64/kvm/hyp/nvhe/switch.c        |  4 +--
 3 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index b5f95abd23f5..cc6cdea69596 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c

@@ -121,11 +121,22 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 	local_irq_save(flags);
 
 	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
-		if (guest_has_sve)
+		if (guest_has_sve) {
 			__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
 
+			/* Restore the VL that was saved when bound to the CPU */
+			if (!has_vhe()) {
+				u64 zcr;
+
+				kvm_call_hyp(__kvm_reset_sve_vq);