Re: [PATCH 12/14] KVM: arm/arm64: arch_timer: Assign the phys timer on VHE systems

Alexandru Elisei
2019-02-19T11:39:50Z

On 1/24/19 2:00 PM, Christoffer Dall wrote:
> 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@arm.com>
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
> ---
> 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()) {
> + 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);
> }
>
> int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
> @@ -814,6 +886,8 @@ int kvm_timer_hyp_init(bool has_gic)
> return -ENODEV;
> }
>
> + /* First, do the virtual EL1 timer irq */
> +
> if (info->virtual_irq <= 0) {
> kvm_err("kvm_arch_timer: invalid virtual timer IRQ: %d\n",
> info->virtual_irq);
> @@ -824,15 +898,15 @@ int kvm_timer_hyp_init(bool has_gic)
> host_vtimer_irq_flags = irq_get_trigger_type(host_vtimer_irq);
> if (host_vtimer_irq_flags != IRQF_TRIGGER_HIGH &&
> host_vtimer_irq_flags != IRQF_TRIGGER_LOW) {
> - kvm_err("Invalid trigger for IRQ%d, assuming level low\n",
> + kvm_err("Invalid trigger for vtimer IRQ%d, assuming level low\n",
> host_vtimer_irq);
> host_vtimer_irq_flags = IRQF_TRIGGER_LOW;
> }
>
> err = request_percpu_irq(host_vtimer_irq, kvm_arch_timer_handler,
> - "kvm guest timer", kvm_get_running_vcpus());
> + "kvm guest vtimer", kvm_get_running_vcpus());
> if (err) {
> - kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
> + kvm_err("kvm_arch_timer: can't request vtimer interrupt %d (%d)\n",
> host_vtimer_irq, err);
> return err;
> }
> @@ -850,6 +924,38 @@ int kvm_timer_hyp_init(bool has_gic)
>
> kvm_debug("virtual timer IRQ%d\n", host_vtimer_irq);
>
> + /* Now let's do the physical EL1 timer irq */
> +
> + if (info->physical_irq > 0) {
> + host_ptimer_irq = info->physical_irq;
> + host_ptimer_irq_flags = irq_get_trigger_type(host_ptimer_irq);
> + if (host_ptimer_irq_flags != IRQF_TRIGGER_HIGH &&
> + host_ptimer_irq_flags != IRQF_TRIGGER_LOW) {
> + kvm_err("Invalid trigger for ptimer IRQ%d, assuming level low\n",
> + host_ptimer_irq);
> + host_ptimer_irq_flags = IRQF_TRIGGER_LOW;
> + }
> +
> + err = request_percpu_irq(host_ptimer_irq, kvm_arch_timer_handler,
> + "kvm guest ptimer", kvm_get_running_vcpus());
> + if (err) {
> + kvm_err("kvm_arch_timer: can't request ptimer interrupt %d (%d)\n",
> + host_ptimer_irq, err);
> + return err;
> + }
> +
> + if (has_gic) {
> + err = irq_set_vcpu_affinity(host_ptimer_irq,
> + kvm_get_running_vcpus());
> + if (err) {
> + kvm_err("kvm_arch_timer: error setting vcpu affinity\n");
> + goto out_free_irq;
> + }
> + }
> +
> + kvm_debug("physical timer IRQ%d\n", host_ptimer_irq);
> + }
> +
> cpuhp_setup_state(CPUHP_AP_KVM_ARM_TIMER_STARTING,
> "kvm/arm/timer:starting", kvm_timer_starting_cpu,
> kvm_timer_dying_cpu);
> @@ -897,8 +1003,10 @@ bool kvm_arch_timer_get_input_level(int vintid)
>
> if (vintid == vcpu_vtimer(vcpu)->irq.irq)
> timer = vcpu_vtimer(vcpu);
> + else if (vintid == vcpu_ptimer(vcpu)->irq.irq)
> + timer = vcpu_ptimer(vcpu);
> else
> - BUG(); /* We only map the vtimer so far */
> + BUG();
>
> return kvm_timer_should_fire(timer);
> }
> @@ -907,6 +1015,7 @@ int kvm_timer_enable(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);
> int ret;
>
> if (timer->enabled)
> @@ -929,6 +1038,13 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
> if (ret)
> return ret;
>
> + if (has_vhe()) {
> + ret = kvm_vgic_map_phys_irq(vcpu, host_ptimer_irq, ptimer->irq.irq,
> + kvm_arch_timer_get_input_level);
> + if (ret)
> + return ret;
> + }
> +
> no_vgic:
> timer->enabled = 1;
> return 0;
> @@ -951,7 +1067,7 @@ void kvm_timer_init_vhe(void)
> * Physical counter access is allowed.
> */
This trimmed comment and the comment for the function still state that physical
timer access is trapped from the guest. I think both comments should be updated
to reflect that that isn't the case anymore.
> val = read_sysreg(cnthctl_el2);
> - val &= ~(CNTHCTL_EL1PCEN << cnthctl_shift);
> + val |= (CNTHCTL_EL1PCEN << cnthctl_shift);
> val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
> write_sysreg(val, cnthctl_el2);
> }