Re: [PATCH 03/13] KVM: arm64: Replace timer context vcpu pointer with timer_id

[Joey Gouly <joey.gouly@arm.com>]

On Mon, Sep 29, 2025 at 05:04:47PM +0100, Marc Zyngier wrote:
> Having to follow a pointer to a vcpu is pretty dumb, when the timers
> are are a fixed offset in the vcpu structure itself.
> 
> Trade the vcpu pointer for a timer_id, which can then be used to
> compute the vcpu address as needed.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

> ---
>  arch/arm64/kvm/arch_timer.c  |  4 ++--
>  include/kvm/arm_arch_timer.h | 11 ++++++-----
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> index e5a25e743f5be..c832c293676a3 100644
> --- a/arch/arm64/kvm/arch_timer.c
> +++ b/arch/arm64/kvm/arch_timer.c
> @@ -149,7 +149,7 @@ static void timer_set_cval(struct arch_timer_context *ctxt, u64 cval)
>  static void timer_set_offset(struct arch_timer_context *ctxt, u64 offset)
>  {
>  	if (!ctxt->offset.vm_offset) {
> -		WARN(offset, "timer %ld\n", arch_timer_ctx_index(ctxt));
> +		WARN(offset, "timer %d\n", arch_timer_ctx_index(ctxt));
>  		return;
>  	}
>  
> @@ -1064,7 +1064,7 @@ static void timer_context_init(struct kvm_vcpu *vcpu, int timerid)
>  	struct arch_timer_context *ctxt = vcpu_get_timer(vcpu, timerid);
>  	struct kvm *kvm = vcpu->kvm;
>  
> -	ctxt->vcpu = vcpu;
> +	ctxt->timer_id = timerid;
>  
>  	if (timerid == TIMER_VTIMER)
>  		ctxt->offset.vm_offset = &kvm->arch.timer_data.voffset;
> diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
> index d188c716d03cb..d8e400cb2bfff 100644
> --- a/include/kvm/arm_arch_timer.h
> +++ b/include/kvm/arm_arch_timer.h
> @@ -51,8 +51,6 @@ struct arch_timer_vm_data {
>  };
>  
>  struct arch_timer_context {
> -	struct kvm_vcpu			*vcpu;
> -
>  	/* Emulated Timer (may be unused) */
>  	struct hrtimer			hrtimer;
>  	u64				ns_frac;
> @@ -71,6 +69,9 @@ struct arch_timer_context {
>  		bool			level;
>  	} irq;
>  
> +	/* Who am I? */
> +	enum kvm_arch_timers		timer_id;
> +
>  	/* Duplicated state from arch_timer.c for convenience */
>  	u32				host_timer_irq;
>  };
> @@ -127,9 +128,9 @@ void kvm_timer_init_vhe(void);
>  #define vcpu_hvtimer(v)	(&(v)->arch.timer_cpu.timers[TIMER_HVTIMER])
>  #define vcpu_hptimer(v)	(&(v)->arch.timer_cpu.timers[TIMER_HPTIMER])
>  
> -#define arch_timer_ctx_index(ctx)	((ctx) - vcpu_timer((ctx)->vcpu)->timers)
> -#define timer_context_to_vcpu(ctx)	((ctx)->vcpu)
> -#define timer_vm_data(ctx)		(&(ctx)->vcpu->kvm->arch.timer_data)
> +#define arch_timer_ctx_index(ctx)	((ctx)->timer_id)
> +#define timer_context_to_vcpu(ctx)	container_of((ctx), struct kvm_vcpu, arch.timer_cpu.timers[(ctx)->timer_id])
> +#define timer_vm_data(ctx)		(&(timer_context_to_vcpu(ctx)->kvm->arch.timer_data))
>  #define timer_irq(ctx)			(timer_vm_data(ctx)->ppi[arch_timer_ctx_index(ctx)])
>  
>  u64 kvm_arm_timer_read_sysreg(struct kvm_vcpu *vcpu,
> -- 
> 2.47.3
>