It is possible that the guest hypervisor has selected a smaller VL than the maximum for its nested guest. As such, ZCR_EL2 may be configured for a different VL when exiting a nested guest. Set ZCR_EL2 (via the EL1 alias) to the maximum VL for the VM before saving SVE state as the SVE save area is dimensioned by the max VL. Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx> --- arch/arm64/kvm/fpsimd.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 53168bbea8a7..bb2ef3166c63 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -193,11 +193,14 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) * Note that this means that at guest exit ZCR_EL1 is * not necessarily the same as on guest entry. * - * Restoring the VL isn't needed in VHE mode since - * ZCR_EL2 (accessed via ZCR_EL1) would fulfill the same - * role when doing the save from EL2. + * ZCR_EL2 holds the guest hypervisor's VL when running + * a nested guest, which could be smaller than the + * max for the vCPU. Similar to above, we first need to + * switch to a VL consistent with the layout of the + * vCPU's SVE state. KVM support for NV implies VHE, so + * using the ZCR_EL1 alias is safe. */ - if (!has_vhe()) + if (!has_vhe() || (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu))) sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL1); } -- 2.45.1.288.g0e0cd299f1-goog
