On Mon, Feb 18, 2019 at 03:10:49PM +0000, André Przywara wrote:
> On Thu, 24 Jan 2019 15:00:30 +0100
> Christoffer Dall <christoffer.dall@xxxxxxx> wrote:
>
> Hi,
>
> > VHE systems don't have to emulate the physical timer, we can simply
> > assigne the EL1 physical timer directly to the VM as the host always
> > uses the EL2 timers.
> >
> > In order to minimize the amount of cruft, AArch32 gets definitions for
> > the physical timer too, but is should be generally unused on this
> > architecture.
> >
> > Co-written with Marc Zyngier <marc.zyngier@xxxxxxx>
> >
> > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> > Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> > ---
> > arch/arm/include/asm/kvm_hyp.h | 4 +
> > include/kvm/arm_arch_timer.h | 6 +
> > virt/kvm/arm/arch_timer.c | 206 ++++++++++++++++++++++++++-------
> > 3 files changed, 171 insertions(+), 45 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/kvm_hyp.h b/arch/arm/include/asm/kvm_hyp.h
> > index e93a0cac9add..87bcd18df8d5 100644
> > --- a/arch/arm/include/asm/kvm_hyp.h
> > +++ b/arch/arm/include/asm/kvm_hyp.h
> > @@ -40,6 +40,7 @@
> > #define TTBR1 __ACCESS_CP15_64(1, c2)
> > #define VTTBR __ACCESS_CP15_64(6, c2)
> > #define PAR __ACCESS_CP15_64(0, c7)
> > +#define CNTP_CVAL __ACCESS_CP15_64(2, c14)
> > #define CNTV_CVAL __ACCESS_CP15_64(3, c14)
> > #define CNTVOFF __ACCESS_CP15_64(4, c14)
> >
> > @@ -85,6 +86,7 @@
> > #define TID_PRIV __ACCESS_CP15(c13, 0, c0, 4)
> > #define HTPIDR __ACCESS_CP15(c13, 4, c0, 2)
> > #define CNTKCTL __ACCESS_CP15(c14, 0, c1, 0)
> > +#define CNTP_CTL __ACCESS_CP15(c14, 0, c2, 1)
> > #define CNTV_CTL __ACCESS_CP15(c14, 0, c3, 1)
> > #define CNTHCTL __ACCESS_CP15(c14, 4, c1, 0)
> >
> > @@ -94,6 +96,8 @@
> > #define read_sysreg_el0(r) read_sysreg(r##_el0)
> > #define write_sysreg_el0(v, r) write_sysreg(v, r##_el0)
> >
> > +#define cntp_ctl_el0 CNTP_CTL
> > +#define cntp_cval_el0 CNTP_CVAL
> > #define cntv_ctl_el0 CNTV_CTL
> > #define cntv_cval_el0 CNTV_CVAL
> > #define cntvoff_el2 CNTVOFF
> > diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
> > index d40fe57a2d0d..722e0481f310 100644
> > --- a/include/kvm/arm_arch_timer.h
> > +++ b/include/kvm/arm_arch_timer.h
> > @@ -50,6 +50,10 @@ struct arch_timer_context {
> >
> > /* Emulated Timer (may be unused) */
> > struct hrtimer hrtimer;
> > +
> > + /* Duplicated state from arch_timer.c for convenience */
> > + u32 host_timer_irq;
> > + u32 host_timer_irq_flags;
> > };
> >
> > enum loaded_timer_state {
> > @@ -107,6 +111,8 @@ bool kvm_arch_timer_get_input_level(int vintid);
> > #define vcpu_vtimer(v) (&(v)->arch.timer_cpu.timers[TIMER_VTIMER])
> > #define vcpu_ptimer(v) (&(v)->arch.timer_cpu.timers[TIMER_PTIMER])
> >
> > +#define arch_timer_ctx_index(ctx) ((ctx) - vcpu_timer((ctx)->vcpu)->timers)
> > +
> > u64 kvm_arm_timer_read_sysreg(struct kvm_vcpu *vcpu,
> > enum kvm_arch_timers tmr,
> > enum kvm_arch_timer_regs treg);
> > diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
> > index 8b0eca5fbad1..eed8f48fbf9b 100644
> > --- a/virt/kvm/arm/arch_timer.c
> > +++ b/virt/kvm/arm/arch_timer.c
> > @@ -35,7 +35,9 @@
> >
> > static struct timecounter *timecounter;
> > static unsigned int host_vtimer_irq;
> > +static unsigned int host_ptimer_irq;
> > static u32 host_vtimer_irq_flags;
> > +static u32 host_ptimer_irq_flags;
> >
> > static DEFINE_STATIC_KEY_FALSE(has_gic_active_state);
> >
> > @@ -86,20 +88,24 @@ static void soft_timer_cancel(struct hrtimer *hrt)
> > static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
> > {
> > struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
> > - struct arch_timer_context *vtimer;
> > + struct arch_timer_context *ctx;
> >
> > /*
> > * We may see a timer interrupt after vcpu_put() has been called which
> > * sets the CPU's vcpu pointer to NULL, because even though the timer
> > - * has been disabled in vtimer_save_state(), the hardware interrupt
> > + * has been disabled in timer_save_state(), the hardware interrupt
> > * signal may not have been retired from the interrupt controller yet.
> > */
> > if (!vcpu)
> > return IRQ_HANDLED;
> >
> > - vtimer = vcpu_vtimer(vcpu);
> > - if (kvm_timer_should_fire(vtimer))
> > - kvm_timer_update_irq(vcpu, true, vtimer);
> > + if (irq == host_vtimer_irq)
> > + ctx = vcpu_vtimer(vcpu);
> > + else
> > + ctx = vcpu_ptimer(vcpu);
> > +
> > + if (kvm_timer_should_fire(ctx))
> > + kvm_timer_update_irq(vcpu, true, ctx);
> >
> > if (userspace_irqchip(vcpu->kvm) &&
> > !static_branch_unlikely(&has_gic_active_state))
> > @@ -208,13 +214,25 @@ 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);
> > + enum kvm_arch_timers index = arch_timer_ctx_index(timer_ctx);
> > u64 cval, now;
> >
> > if (timer->loaded == TIMER_EL1_LOADED) {
> > - u32 cnt_ctl;
> > + u32 cnt_ctl = 0;
> > +
> > + switch (index) {
> > + case TIMER_VTIMER:
> > + cnt_ctl = read_sysreg_el0(cntv_ctl);
> > + break;
> > + case TIMER_PTIMER:
> > + cnt_ctl = read_sysreg_el0(cntp_ctl);
> > + break;
> > + case NR_KVM_TIMERS:
> > + /* GCC is braindead */
> > + cnt_ctl = 0;
> > + break;
> > + }
> >
> > - /* Only the virtual timer can be loaded so far */
> > - cnt_ctl = read_sysreg_el0(cntv_ctl);
> > return (cnt_ctl & ARCH_TIMER_CTRL_ENABLE) &&
> > (cnt_ctl & ARCH_TIMER_CTRL_IT_STAT) &&
> > !(cnt_ctl & ARCH_TIMER_CTRL_IT_MASK);
> > @@ -310,7 +328,7 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
> > return;
> >
> > /*
> > - * The vtimer virtual interrupt is a 'mapped' interrupt, meaning part
> > + * If the timer virtual interrupt is a 'mapped' interrupt, part
> > * of its lifecycle is offloaded to the hardware, and we therefore may
> > * not have lowered the irq.level value before having to signal a new
> > * interrupt, but have to signal an interrupt every time the level is
> > @@ -319,31 +337,55 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
> > level = kvm_timer_should_fire(vtimer);
> > kvm_timer_update_irq(vcpu, level, vtimer);
> >
> > + if (has_vhe()) {
>
> Not really critical, but wouldn't it be cleaner to use "if
> (host_ptimer_irq > 0)" here to check if we map the phys timer as well?
> This is at least how we originally derive the decision to initialise
> everything in kvm_timer_hyp_init() below. Applies to the other instances
> of "if (has_vhe())" as well.
> But I guess we use has_vhe() because it's a static key? In this case
> would it be worth to define some cosmetic wrapper, to improve readability?
>
> > + level = kvm_timer_should_fire(ptimer);
> > + kvm_timer_update_irq(vcpu, level, ptimer);
> > +
> > + return;
> > + }
> > +
> > phys_timer_emulate(vcpu);
> >
> > if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
> > kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
> > }
> >
> > -static void vtimer_save_state(struct kvm_vcpu *vcpu)
> > +static void timer_save_state(struct arch_timer_context *ctx)
> > {
> > - struct arch_timer_cpu *timer = vcpu_timer(vcpu);
> > - struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
> > + struct arch_timer_cpu *timer = vcpu_timer(ctx->vcpu);
> > + enum kvm_arch_timers index = arch_timer_ctx_index(ctx);
> > unsigned long flags;
> >
> > + if (!timer->enabled)
> > + return;
> > +
> > local_irq_save(flags);
> >
> > if (timer->loaded == TIMER_NOT_LOADED)
> > goto out;
> >
> > - if (timer->enabled) {
> > - vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl);
> > - vtimer->cnt_cval = read_sysreg_el0(cntv_cval);
> > - }
> > + switch (index) {
> > + case TIMER_VTIMER:
> > + ctx->cnt_ctl = read_sysreg_el0(cntv_ctl);
> > + ctx->cnt_cval = read_sysreg_el0(cntv_cval);
> >
> > - /* Disable the virtual timer */
> > - write_sysreg_el0(0, cntv_ctl);
> > - isb();
> > + /* Disable the timer */
> > + write_sysreg_el0(0, cntv_ctl);
> > + isb();
> > +
> > + break;
> > + case TIMER_PTIMER:
> > + ctx->cnt_ctl = read_sysreg_el0(cntp_ctl);
> > + ctx->cnt_cval = read_sysreg_el0(cntp_cval);
> > +
> > + /* Disable the timer */
> > + write_sysreg_el0(0, cntp_ctl);
> > + isb();
> > +
> > + break;
> > + case NR_KVM_TIMERS:
> > + break; /* GCC is braindead */
> > + }
> >
> > timer->loaded = TIMER_NOT_LOADED;
> > out:
> > @@ -382,21 +424,33 @@ static void kvm_timer_unblocking(struct kvm_vcpu *vcpu)
> > soft_timer_cancel(&timer->bg_timer);
> > }
> >
> > -static void vtimer_restore_state(struct kvm_vcpu *vcpu)
> > +static void timer_restore_state(struct arch_timer_context *ctx)
> > {
> > - struct arch_timer_cpu *timer = vcpu_timer(vcpu);
> > - struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
> > + struct arch_timer_cpu *timer = vcpu_timer(ctx->vcpu);
> > + enum kvm_arch_timers index = arch_timer_ctx_index(ctx);
> > unsigned long flags;
> >
> > + if (!timer->enabled)
> > + return;
> > +
> > local_irq_save(flags);
> >
> > if (timer->loaded == TIMER_EL1_LOADED)
> > goto out;
> >
> > - if (timer->enabled) {
> > - write_sysreg_el0(vtimer->cnt_cval, cntv_cval);
> > + switch (index) {
> > + case TIMER_VTIMER:
> > + write_sysreg_el0(ctx->cnt_cval, cntv_cval);
> > + isb();
> > + write_sysreg_el0(ctx->cnt_ctl, cntv_ctl);
> > + break;
> > + case TIMER_PTIMER:
> > + write_sysreg_el0(ctx->cnt_cval, cntp_cval);
> > isb();
> > - write_sysreg_el0(vtimer->cnt_ctl, cntv_ctl);
> > + write_sysreg_el0(ctx->cnt_ctl, cntp_ctl);
> > + break;
> > + case NR_KVM_TIMERS:
> > + break; /* GCC is braindead */
> > }
> >
> > timer->loaded = TIMER_EL1_LOADED;
> > @@ -419,23 +473,23 @@ static void set_cntvoff(u64 cntvoff)
> > kvm_call_hyp(__kvm_timer_set_cntvoff, low, high);
> > }
> >
> > -static inline void set_vtimer_irq_phys_active(struct kvm_vcpu *vcpu, bool active)
> > +static inline void set_timer_irq_phys_active(struct arch_timer_context *ctx, bool active)
> > {
> > int r;
> > - r = irq_set_irqchip_state(host_vtimer_irq, IRQCHIP_STATE_ACTIVE, active);
> > + r = irq_set_irqchip_state(ctx->host_timer_irq, IRQCHIP_STATE_ACTIVE, active);
> > WARN_ON(r);
> > }
> >
> > -static void kvm_timer_vcpu_load_gic(struct kvm_vcpu *vcpu)
> > +static void kvm_timer_vcpu_load_gic(struct arch_timer_context *ctx)
> > {
> > - struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
> > + struct kvm_vcpu *vcpu = ctx->vcpu;
> > bool phys_active;
> >
> > if (irqchip_in_kernel(vcpu->kvm))
> > - phys_active = kvm_vgic_map_is_active(vcpu, vtimer->irq.irq);
> > + phys_active = kvm_vgic_map_is_active(vcpu, ctx->irq.irq);
> > else
> > - phys_active = vtimer->irq.level;
> > - set_vtimer_irq_phys_active(vcpu, phys_active);
> > + phys_active = ctx->irq.level;
> > + set_timer_irq_phys_active(ctx, phys_active);
> > }
> >
> > static void kvm_timer_vcpu_load_nogic(struct kvm_vcpu *vcpu)
> > @@ -467,14 +521,22 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
> > if (unlikely(!timer->enabled))
> > return;
> >
> > - if (static_branch_likely(&has_gic_active_state))
> > - kvm_timer_vcpu_load_gic(vcpu);
> > - else
> > + if (static_branch_likely(&has_gic_active_state)) {
> > + kvm_timer_vcpu_load_gic(vtimer);
> > + if (has_vhe())
> > + kvm_timer_vcpu_load_gic(ptimer);
> > + } else {
> > kvm_timer_vcpu_load_nogic(vcpu);
> > + }
> >
> > set_cntvoff(vtimer->cntvoff);
> >
> > - vtimer_restore_state(vcpu);
> > + timer_restore_state(vtimer);
> > +
> > + if (has_vhe()) {
> > + timer_restore_state(ptimer);
> > + return;
> > + }
> >
> > /* Set the background timer for the physical timer emulation. */
> > phys_timer_emulate(vcpu);
> > @@ -506,12 +568,17 @@ 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_timer(vcpu);
> > + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
> > struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
> >
> > if (unlikely(!timer->enabled))
> > return;
> >
> > - vtimer_save_state(vcpu);
> > + timer_save_state(vtimer);
> > + if (has_vhe()) {
> > + timer_save_state(ptimer);
> > + return;
> > + }
> >
> > /*
> > * Cancel the physical timer emulation, because the only case where we
> > @@ -534,8 +601,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
> > * counter of non-VHE case. For VHE, the virtual counter uses a fixed
> > * virtual offset of zero, so no need to zero CNTVOFF_EL2 register.
> > */
> > - if (!has_vhe())
> > - set_cntvoff(0);
> > + set_cntvoff(0);
> > }
> >
> > /*
> > @@ -550,7 +616,7 @@ static void unmask_vtimer_irq_user(struct kvm_vcpu *vcpu)
> > if (!kvm_timer_should_fire(vtimer)) {
> > kvm_timer_update_irq(vcpu, false, vtimer);
> > if (static_branch_likely(&has_gic_active_state))
> > - set_vtimer_irq_phys_active(vcpu, false);
> > + set_timer_irq_phys_active(vtimer, false);
> > else
> > enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
> > }
> > @@ -625,7 +691,12 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
> > ptimer->hrtimer.function = kvm_phys_timer_expire;
> >
> > vtimer->irq.irq = default_vtimer_irq.irq;
> > + vtimer->host_timer_irq = host_vtimer_irq;
> > + vtimer->host_timer_irq_flags = host_vtimer_irq_flags;
> > +
> > ptimer->irq.irq = default_ptimer_irq.irq;
> > + ptimer->host_timer_irq = host_ptimer_irq;
> > + ptimer->host_timer_irq_flags = host_ptimer_irq_flags;
> >
> > vtimer->vcpu = vcpu;
> > ptimer->vcpu = vcpu;
> > @@ -634,6 +705,7 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
> > static void kvm_timer_init_interrupt(void *info)
> > {
> > enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags);
> > + enable_percpu_irq(host_ptimer_irq, host_ptimer_irq_flags);
>
> Shouldn't we only enable host_ptimer_irq() if we actually pass this on
> here? So either guarded by has_vhe() or (host_ptimer_irq > 0)?
> Otherwise we would enable IRQ 0?
>
I think the right fix is to raise an error if a VHE system doesn't give
us a valid physical irq number during init, and then leave the checks
for has_vhe() here.
Thanks,
Christoffer
