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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 <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2025-09-29 17:04:53 +01:00
parent c3be3a48fb
commit 892f7c38ba
1 changed files with 6 additions and 1 deletions
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7
arch/arm64/kvm/handle_exit.c
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@ -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)