[PATCH 11/14] KVM: arm/arm64: timer: Rework data structures for multiple timers

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On Thu, 24 Jan 2019 15:00:29 +0100
Christoffer Dall <christoffer.dall at arm.com> wrote:

Hi,

I already looked at most of these patches earlier, without finding
serious issues, but figured I would give those without any Reviewed-by:
or Acked-by: tags a closer look.
(This patch just carries a S-o-b: tag from Marc in the kvm-arm git repo.)

> Prepare for having 4 timer data structures (2 for now).
> 
> Change loaded to an enum so that we know not just whether *some* state
> is loaded on the CPU, but also *which* state is loaded.
> 
> Move loaded to the cpu data structure and not the individual timer
> structure, in preparation for assigning the EL1 phys timer as well.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall at arm.com>
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  include/kvm/arm_arch_timer.h | 44 ++++++++++++++-------------
>  virt/kvm/arm/arch_timer.c    | 58 +++++++++++++++++++-----------------
>  2 files changed, 54 insertions(+), 48 deletions(-)
> 
> diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
> index d26b7fde9935..d40fe57a2d0d 100644
> --- a/include/kvm/arm_arch_timer.h
> +++ b/include/kvm/arm_arch_timer.h
> @@ -36,6 +36,8 @@ enum kvm_arch_timer_regs {
>  };
>  
>  struct arch_timer_context {
> +	struct kvm_vcpu			*vcpu;
> +
>  	/* Registers: control register, timer value */
>  	u32				cnt_ctl;
>  	u64				cnt_cval;
> @@ -43,32 +45,34 @@ struct arch_timer_context {
>  	/* Timer IRQ */
>  	struct kvm_irq_level		irq;
>  
> -	/*
> -	 * We have multiple paths which can save/restore the timer state
> -	 * onto the hardware, so we need some way of keeping track of
> -	 * where the latest state is.
> -	 *
> -	 * loaded == true:  State is loaded on the hardware registers.
> -	 * loaded == false: State is stored in memory.
> -	 */
> -	bool			loaded;
> -
>  	/* Virtual offset */
> -	u64			cntvoff;
> +	u64				cntvoff;
> +
> +	/* Emulated Timer (may be unused) */
> +	struct hrtimer			hrtimer;
> +};
> +
> +enum loaded_timer_state {
> +	TIMER_NOT_LOADED,
> +	TIMER_EL1_LOADED,

So this gets reverted in PATCH 13/14, and I don't see it reappearing in
the nv series later on.
Is that just needed for assigning the phys timer in the next patch, and
gets obsolete with the timer_map?
Or is this a rebase artefact and we don't actually need this?

The rest of the patch looks like valid transformations to me.

Cheers,
Andre.

>  };
>  
>  struct arch_timer_cpu {
> -	struct arch_timer_context	vtimer;
> -	struct arch_timer_context	ptimer;
> +	struct arch_timer_context timers[NR_KVM_TIMERS];
>  
>  	/* Background timer used when the guest is not running */
>  	struct hrtimer			bg_timer;
>  
> -	/* Physical timer emulation */
> -	struct hrtimer			phys_timer;
> -
>  	/* Is the timer enabled */
>  	bool			enabled;
> +
> +	/*
> +	 * We have multiple paths which can save/restore the timer state
> +	 * onto the hardware, and for nested virt the EL1 hardware timers can
> +	 * contain state from either the VM's EL1 timers or EL2 timers, so we
> +	 * need some way of keeping track of where the latest state is.
> +	 */
> +	enum loaded_timer_state loaded;
>  };
>  
>  int kvm_timer_hyp_init(bool);
> @@ -98,10 +102,10 @@ void kvm_timer_init_vhe(void);
>  
>  bool kvm_arch_timer_get_input_level(int vintid);
>  
> -#define vcpu_vtimer(v)	(&(v)->arch.timer_cpu.vtimer)
> -#define vcpu_ptimer(v)	(&(v)->arch.timer_cpu.ptimer)
> -#define vcpu_get_timer(v,t)					\
> -	(t == TIMER_VTIMER ? vcpu_vtimer(v) : vcpu_ptimer(v))
> +#define vcpu_timer(v)	(&(v)->arch.timer_cpu)
> +#define vcpu_get_timer(v,t)	(&vcpu_timer(v)->timers[(t)])
> +#define vcpu_vtimer(v)	(&(v)->arch.timer_cpu.timers[TIMER_VTIMER])
> +#define vcpu_ptimer(v)	(&(v)->arch.timer_cpu.timers[TIMER_PTIMER])
>  
>  u64 kvm_arm_timer_read_sysreg(struct kvm_vcpu *vcpu,
>  			      enum kvm_arch_timers tmr,
> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> index 9502bb91776b..8b0eca5fbad1 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -184,13 +184,11 @@ static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt)
>  static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt)
>  {
>  	struct arch_timer_context *ptimer;
> -	struct arch_timer_cpu *timer;
>  	struct kvm_vcpu *vcpu;
>  	u64 ns;
>  
> -	timer = container_of(hrt, struct arch_timer_cpu, phys_timer);
> -	vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
> -	ptimer = vcpu_ptimer(vcpu);
> +	ptimer = container_of(hrt, struct arch_timer_context, hrtimer);
> +	vcpu = ptimer->vcpu;
>  
>  	/*
>  	 * Check that the timer has really expired from the guest's
> @@ -209,9 +207,10 @@ static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt)
>  
>  static bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx)
>  {
> +	struct arch_timer_cpu *timer = vcpu_timer(timer_ctx->vcpu);
>  	u64 cval, now;
>  
> -	if (timer_ctx->loaded) {
> +	if (timer->loaded == TIMER_EL1_LOADED) {
>  		u32 cnt_ctl;
>  
>  		/* Only the virtual timer can be loaded so far */
> @@ -280,7 +279,6 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
>  /* Schedule the background timer for the emulated timer. */
>  static void phys_timer_emulate(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
>  	/*
> @@ -289,11 +287,11 @@ static void phys_timer_emulate(struct kvm_vcpu *vcpu)
>  	 * then we also don't need a soft timer.
>  	 */
>  	if (kvm_timer_should_fire(ptimer) || !kvm_timer_irq_can_fire(ptimer)) {
> -		soft_timer_cancel(&timer->phys_timer);
> +		soft_timer_cancel(&ptimer->hrtimer);
>  		return;
>  	}
>  
> -	soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(ptimer));
> +	soft_timer_start(&ptimer->hrtimer, kvm_timer_compute_delta(ptimer));
>  }
>  
>  /*
> @@ -303,7 +301,7 @@ static void phys_timer_emulate(struct kvm_vcpu *vcpu)
>   */
>  static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  	bool level;
> @@ -329,13 +327,13 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
>  
>  static void vtimer_save_state(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	unsigned long flags;
>  
>  	local_irq_save(flags);
>  
> -	if (!vtimer->loaded)
> +	if (timer->loaded == TIMER_NOT_LOADED)
>  		goto out;
>  
>  	if (timer->enabled) {
> @@ -347,7 +345,7 @@ static void vtimer_save_state(struct kvm_vcpu *vcpu)
>  	write_sysreg_el0(0, cntv_ctl);
>  	isb();
>  
> -	vtimer->loaded = false;
> +	timer->loaded = TIMER_NOT_LOADED;
>  out:
>  	local_irq_restore(flags);
>  }
> @@ -359,7 +357,7 @@ static void vtimer_save_state(struct kvm_vcpu *vcpu)
>   */
>  static void kvm_timer_blocking(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
> @@ -379,20 +377,20 @@ static void kvm_timer_blocking(struct kvm_vcpu *vcpu)
>  
>  static void kvm_timer_unblocking(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  
>  	soft_timer_cancel(&timer->bg_timer);
>  }
>  
>  static void vtimer_restore_state(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	unsigned long flags;
>  
>  	local_irq_save(flags);
>  
> -	if (vtimer->loaded)
> +	if (timer->loaded == TIMER_EL1_LOADED)
>  		goto out;
>  
>  	if (timer->enabled) {
> @@ -401,7 +399,7 @@ static void vtimer_restore_state(struct kvm_vcpu *vcpu)
>  		write_sysreg_el0(vtimer->cnt_ctl, cntv_ctl);
>  	}
>  
> -	vtimer->loaded = true;
> +	timer->loaded = TIMER_EL1_LOADED;
>  out:
>  	local_irq_restore(flags);
>  }
> @@ -462,7 +460,7 @@ static void kvm_timer_vcpu_load_nogic(struct kvm_vcpu *vcpu)
>  
>  void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
> @@ -507,7 +505,8 @@ bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)
>  
>  void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
> +	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
>  	if (unlikely(!timer->enabled))
>  		return;
> @@ -523,7 +522,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
>  	 * In any case, we re-schedule the hrtimer for the physical timer when
>  	 * coming back to the VCPU thread in kvm_timer_vcpu_load().
>  	 */
> -	soft_timer_cancel(&timer->phys_timer);
> +	soft_timer_cancel(&ptimer->hrtimer);
>  
>  	if (swait_active(kvm_arch_vcpu_wq(vcpu)))
>  		kvm_timer_blocking(vcpu);
> @@ -559,7 +558,7 @@ static void unmask_vtimer_irq_user(struct kvm_vcpu *vcpu)
>  
>  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  
>  	if (unlikely(!timer->enabled))
>  		return;
> @@ -570,7 +569,7 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>  
>  int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
> @@ -611,22 +610,25 @@ static void update_vtimer_cntvoff(struct kvm_vcpu *vcpu, u64 cntvoff)
>  
>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>  
>  	/* Synchronize cntvoff across all vtimers of a VM. */
>  	update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
> -	vcpu_ptimer(vcpu)->cntvoff = 0;
> +	ptimer->cntvoff = 0;
>  
>  	hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
>  	timer->bg_timer.function = kvm_bg_timer_expire;
>  
> -	hrtimer_init(&timer->phys_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
> -	timer->phys_timer.function = kvm_phys_timer_expire;
> +	hrtimer_init(&ptimer->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
> +	ptimer->hrtimer.function = kvm_phys_timer_expire;
>  
>  	vtimer->irq.irq = default_vtimer_irq.irq;
>  	ptimer->irq.irq = default_ptimer_irq.irq;
> +
> +	vtimer->vcpu = vcpu;
> +	ptimer->vcpu = vcpu;
>  }
>  
>  static void kvm_timer_init_interrupt(void *info)
> @@ -859,7 +861,7 @@ int kvm_timer_hyp_init(bool has_gic)
>  
>  void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  
>  	soft_timer_cancel(&timer->bg_timer);
>  }
> @@ -903,7 +905,7 @@ bool kvm_arch_timer_get_input_level(int vintid)
>  
>  int kvm_timer_enable(struct kvm_vcpu *vcpu)
>  {
> -	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> +	struct arch_timer_cpu *timer = vcpu_timer(vcpu);
>  	struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>  	int ret;
>  



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