Hi Christoffer,

On 01/12/2018 12:07 PM, Christoffer Dall wrote:
The VHE switch function calls __timer_enable_traps and
__timer_disable_traps which don't do anything on VHE systems.
Therefore, simply remove these calls from the VHE switch function and
make the functions non-conditional as they are now only called from the
non-VHE switch path.

Acked-by: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org>
---
  arch/arm64/kvm/hyp/switch.c |  2 --
  virt/kvm/arm/hyp/timer-sr.c | 44 ++++++++++++++++++++++----------------------
  2 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 9aadef6966bf..6175fcb33ed2 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -354,7 +354,6 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
        __activate_vm(vcpu->kvm);
__vgic_restore_state(vcpu);
-       __timer_enable_traps(vcpu);
/*
         * We must restore the 32-bit state before the sysregs, thanks
@@ -373,7 +372,6 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
__sysreg_save_guest_state(guest_ctxt);
        __sysreg32_save_state(vcpu);
-       __timer_disable_traps(vcpu);
        __vgic_save_state(vcpu);
__deactivate_traps(vcpu);
diff --git a/virt/kvm/arm/hyp/timer-sr.c b/virt/kvm/arm/hyp/timer-sr.c
index f24404b3c8df..77754a62eb0c 100644
--- a/virt/kvm/arm/hyp/timer-sr.c
+++ b/virt/kvm/arm/hyp/timer-sr.c
@@ -27,34 +27,34 @@ void __hyp_text __kvm_timer_set_cntvoff(u32 cntvoff_low, 
u32 cntvoff_high)
        write_sysreg(cntvoff, cntvoff_el2);
  }
+/*
+ * Should only be called on non-VHE systems.
+ * VHE systems use EL2 timers and configure EL1 timers in kvm_timer_init_vhe().
+ */
  void __hyp_text __timer_disable_traps(struct kvm_vcpu *vcpu)

Would it be worth to suffix the function with nvhe? So it would be clear that it should not be called for VHE system?

  {
-       /*
-        * We don't need to do this for VHE since the host kernel runs in EL2
-        * with HCR_EL2.TGE ==1, which makes those bits have no impact.
-        */
-       if (!has_vhe()) {
-               u64 val;
+       u64 val;
- /* Allow physical timer/counter access for the host */
-               val = read_sysreg(cnthctl_el2);
-               val |= CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN;
-               write_sysreg(val, cnthctl_el2);
-       }
+       /* Allow physical timer/counter access for the host */
+       val = read_sysreg(cnthctl_el2);
+       val |= CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN;
+       write_sysreg(val, cnthctl_el2);
  }
+/*
+ * Should only be called on non-VHE systems.
+ * VHE systems use EL2 timers and configure EL1 timers in kvm_timer_init_vhe().
+ */
  void __hyp_text __timer_enable_traps(struct kvm_vcpu *vcpu)

Same here.

  {
-       if (!has_vhe()) {
-               u64 val;
+       u64 val;
- /*
-                * Disallow physical timer access for the guest
-                * Physical counter access is allowed
-                */
-               val = read_sysreg(cnthctl_el2);
-               val &= ~CNTHCTL_EL1PCEN;
-               val |= CNTHCTL_EL1PCTEN;
-               write_sysreg(val, cnthctl_el2);
-       }
+       /*
+        * Disallow physical timer access for the guest
+        * Physical counter access is allowed
+        */
+       val = read_sysreg(cnthctl_el2);
+       val &= ~CNTHCTL_EL1PCEN;
+       val |= CNTHCTL_EL1PCTEN;
+       write_sysreg(val, cnthctl_el2);
  }


Cheers,

--
Julien Grall
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