[PATCH v2 06/12] KVM: arm64: nv: Accelerate EL0 counter accesses from hypervisor context

Marc Zyngier
2024-12-17T14:23:27Z

Similarly to handling the physical timer accesses early when FEAT_ECV
causes a trap, we try to handle the physical counter without returning
to the general sysreg handling.

More surprisingly, we introduce something similar for the virtual
counter. Although this isn't necessary yet, it will prove useful on
systems that have a broken CNTVOFF_EL2 implementation. Yes, they exist.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/hyp/vhe/switch.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 51119d58ecff8..ef344bcff09a1 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -324,6 +324,10 @@ static bool kvm_hyp_handle_timer(struct kvm_vcpu *vcpu, u64 *exit_code)
val = __vcpu_sys_reg(vcpu, CNTP_CVAL_EL0);
}
break;
+ case SYS_CNTPCT_EL0:
+ case SYS_CNTPCTSS_EL0:
+ val = compute_counter_value(vcpu_hptimer(vcpu));
+ break;
case SYS_CNTV_CTL_EL02:
val = compute_emulated_cntx_ctl_el0(vcpu, CNTV_CTL_EL0);
break;
@@ -342,6 +346,10 @@ static bool kvm_hyp_handle_timer(struct kvm_vcpu *vcpu, u64 *exit_code)
else
val = __vcpu_sys_reg(vcpu, CNTV_CVAL_EL0);
break;
+ case SYS_CNTVCT_EL0:
+ case SYS_CNTVCTSS_EL0:
+ val = compute_counter_value(vcpu_hvtimer(vcpu));
+ break;
default:
return false;
}
--
2.39.2