Subject: [PATCH v3 17/41] KVM: arm64: Remove noop calls to timer save/restore from VHE switch

From: [email-masked] (Christoffer Dall)
Date: Tue, 13 Feb 2018 23:31:34 +0100

On Fri, Feb 09, 2018 at 05:53:43PM +0000, Julien Grall wrote:
> 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 <[email-masked]>
> >Signed-off-by: Christoffer Dall <[email-masked]>
> >---
> >  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?
> 
Actually, I decided against this, because it's also called from the
32-bit code and it looks a little strange there, and it's not like we
have an equivalent _vhe version.

Thanks,
-Christoffer