From 892f7c38ba3b7de19b3dffb8e148d5fbf1228f20 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 29 Sep 2025 17:04:53 +0100 Subject: [PATCH] KVM: arm64: Fix WFxT handling of nested virt The spec for WFxT indicates that the parameter to the WFxT instruction is relative to the reading of CNTVCT_EL0. This means that the implementation needs to take the execution context into account, as CNTVOFF_EL2 does not always affect readings of CNTVCT_EL0 (such as when HCR_EL2.E2H is 1 and that we're in host context). This also rids us of the last instance of KVM_REG_ARM_TIMER_CNT outside of the userspace interaction code. Signed-off-by: Marc Zyngier --- arch/arm64/kvm/handle_exit.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index bca8c80e11da..cc7d5d1709cb 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -147,7 +147,12 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu) if (esr & ESR_ELx_WFx_ISS_RV) { u64 val, now; - now = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_TIMER_CNT); + now = kvm_phys_timer_read(); + if (is_hyp_ctxt(vcpu) && vcpu_el2_e2h_is_set(vcpu)) + now -= timer_get_offset(vcpu_hvtimer(vcpu)); + else + now -= timer_get_offset(vcpu_vtimer(vcpu)); + val = vcpu_get_reg(vcpu, kvm_vcpu_sys_get_rt(vcpu)); if (now >= val)