[v4,16/40] KVM: arm64: Remove noop calls to timer save/restore from VHE switch

Commit Message

Christoffer Dall Feb. 15, 2018, 9:03 p.m. UTC

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 <[e-mail]>
Signed-off-by: Christoffer Dall <[e-mail]>
---

Notes:
    Changes since v2:
     - Added comment explaining the timer enable/disable functions
       are for !VHE only.

 arch/arm64/kvm/hyp/switch.c |  2 --
 virt/kvm/arm/hyp/timer-sr.c | 44 ++++++++++++++++++++++----------------------
 2 files changed, 22 insertions(+), 24 deletions(-)

Comments

Andrew Jones Feb. 21, 2018, 5:43 p.m. UTC | #1

On Thu, Feb 15, 2018 at 10:03:08PM +0100, 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 <[e-mail]>
> Signed-off-by: Christoffer Dall <[e-mail]>
> ---
> 
> Notes:
>     Changes since v2:
>      - Added comment explaining the timer enable/disable functions
>        are for !VHE only.
> 
>  arch/arm64/kvm/hyp/switch.c |  2 --
>  virt/kvm/arm/hyp/timer-sr.c | 44 ++++++++++++++++++++++----------------------
>  2 files changed, 22 insertions(+), 24 deletions(-)
>

Reviewed-by: Andrew Jones <[e-mail]>

Patch

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 734dac7f808f..f0fae320edc0 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -379,7 +379,6 @@  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
@@ -400,7 +399,6 @@  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)
 {
-	/*
-	 * 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)
 {
-	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);
 }