[PATCH v6 18/21] KVM: arm64: Configure timer traps in vcpu_load() for VHE

[Andrew Jones]

On Wed, Aug 04, 2021 at 08:58:16AM +0000, Oliver Upton wrote:
> In preparation for emulated physical counter-timer offsetting, configure
> traps on every vcpu_load() for VHE systems. As before, these trap
> settings do not affect host userspace, and are only active for the
> guest.
> 
> Suggested-by: Marc Zyngier <maz at kernel.org>
> Signed-off-by: Oliver Upton <oupton at google.com>
> ---
>  arch/arm64/kvm/arch_timer.c  | 10 +++++++---
>  arch/arm64/kvm/arm.c         |  4 +---
>  include/kvm/arm_arch_timer.h |  2 --
>  3 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> index f15058612994..9ead94aa867d 100644
> --- a/arch/arm64/kvm/arch_timer.c
> +++ b/arch/arm64/kvm/arch_timer.c
> @@ -51,6 +51,7 @@ static void kvm_arm_timer_write(struct kvm_vcpu *vcpu,
>  static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu,
>  			      struct arch_timer_context *timer,
>  			      enum kvm_arch_timer_regs treg);
> +static void kvm_timer_enable_traps_vhe(void);
>  
>  u32 timer_get_ctl(struct arch_timer_context *ctxt)
>  {
> @@ -668,6 +669,9 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
>  
>  	if (map.emul_ptimer)
>  		timer_emulate(map.emul_ptimer);
> +
> +	if (has_vhe())
> +		kvm_timer_enable_traps_vhe();
>  }
>  
>  bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)
> @@ -1383,12 +1387,12 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
>  }
>  
>  /*
> - * On VHE system, we only need to configure the EL2 timer trap register once,
> - * not for every world switch.
> + * On VHE system, we only need to configure the EL2 timer trap register on
> + * vcpu_load(), but not every world switch into the guest.
>   * The host kernel runs at EL2 with HCR_EL2.TGE == 1,
>   * and this makes those bits have no effect for the host kernel execution.
>   */
> -void kvm_timer_init_vhe(void)
> +static void kvm_timer_enable_traps_vhe(void)
>  {
>  	/* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */
>  	u32 cnthctl_shift = 10;
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..47ea1e1ba80b 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1558,9 +1558,7 @@ static void cpu_hyp_reinit(void)
>  
>  	cpu_hyp_reset();
>  
> -	if (is_kernel_in_hyp_mode())
> -		kvm_timer_init_vhe();
> -	else
> +	if (!is_kernel_in_hyp_mode())
>  		cpu_init_hyp_mode();
>  
>  	cpu_set_hyp_vector();
> diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
> index 615f9314f6a5..254653b42da0 100644
> --- a/include/kvm/arm_arch_timer.h
> +++ b/include/kvm/arm_arch_timer.h
> @@ -87,8 +87,6 @@ u64 kvm_phys_timer_read(void);
>  void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu);
>  void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu);
>  
> -void kvm_timer_init_vhe(void);
> -
>  bool kvm_arch_timer_get_input_level(int vintid);
>  
>  #define vcpu_timer(v)	(&(v)->arch.timer_cpu)
> -- 
> 2.32.0.605.g8dce9f2422-goog
>

Reviewed-by: Andrew Jones <drjones at redhat.com>