From 8409a06f2a2c0baeb6e6ff020b2c5a4592b3078d Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Sat, 17 Jun 2017 01:09:19 -0700 Subject: KVM: arm/arm64: Make timer_arm and timer_disarm helpers more generic We are about to add an additional soft timer to the arch timer state for a VCPU and would like to be able to reuse the functions to program and cancel a timer, so we make them slightly more generic and rename to make it more clear that these functions work on soft timers and not the hardware resource that this code is managing. The armed flag on the timer state is only used to assert a condition, and we don't rely on this assertion in any meaningful way, so we can simply get rid of this flack and slightly reduce complexity. Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall --- include/kvm/arm_arch_timer.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index f0053f884b4a..d0beae98f755 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -48,9 +48,6 @@ struct arch_timer_cpu { /* Work queued with the above timer expires */ struct work_struct expired; - /* Background timer active */ - bool armed; - /* Is the timer enabled */ bool enabled; }; -- cgit v1.2.3 From 14d61fa98f03cb01f3aea7e3069fdf460caf5587 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Sat, 17 Jun 2017 07:33:02 -0700 Subject: KVM: arm/arm64: Rename soft timer to bg_timer As we are about to introduce a separate hrtimer for the physical timer, call this timer bg_timer, because we refer to this timer as the background timer in the code and comments elsewhere. Signed-off-by: Christoffer Dall Acked-by: Marc Zyngier --- include/kvm/arm_arch_timer.h | 2 +- virt/kvm/arm/arch_timer.c | 18 +++++++++--------- 2 files changed, 10 insertions(+), 10 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index d0beae98f755..0eed5bc9fd5e 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -43,7 +43,7 @@ struct arch_timer_cpu { struct arch_timer_context ptimer; /* Background timer used when the guest is not running */ - struct hrtimer timer; + struct hrtimer bg_timer; /* Work queued with the above timer expires */ struct work_struct expired; diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 223230191195..8ec392850e69 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -148,13 +148,13 @@ static u64 kvm_timer_earliest_exp(struct kvm_vcpu *vcpu) return min(min_virt, min_phys); } -static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) +static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt) { struct arch_timer_cpu *timer; struct kvm_vcpu *vcpu; u64 ns; - timer = container_of(hrt, struct arch_timer_cpu, timer); + timer = container_of(hrt, struct arch_timer_cpu, bg_timer); vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu); /* @@ -261,7 +261,7 @@ static void kvm_timer_emulate(struct kvm_vcpu *vcpu, return; /* The timer has not yet expired, schedule a background timer */ - soft_timer_start(&timer->timer, kvm_timer_compute_delta(timer_ctx)); + soft_timer_start(&timer->bg_timer, kvm_timer_compute_delta(timer_ctx)); } /* @@ -294,14 +294,14 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) * The guest timers have not yet expired, schedule a background timer. * Set the earliest expiration time among the guest timers. */ - soft_timer_start(&timer->timer, kvm_timer_earliest_exp(vcpu)); + soft_timer_start(&timer->bg_timer, kvm_timer_earliest_exp(vcpu)); } void kvm_timer_unschedule(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - soft_timer_cancel(&timer->timer, &timer->expired); + soft_timer_cancel(&timer->bg_timer, &timer->expired); } static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu) @@ -437,7 +437,7 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) * This is to cancel the background timer for the physical timer * emulation if it is set. */ - soft_timer_cancel(&timer->timer, &timer->expired); + soft_timer_cancel(&timer->bg_timer, &timer->expired); /* * The guest could have modified the timer registers or the timer @@ -494,8 +494,8 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) vcpu_ptimer(vcpu)->cntvoff = 0; INIT_WORK(&timer->expired, kvm_timer_inject_irq_work); - hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); - timer->timer.function = kvm_timer_expire; + hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); + timer->bg_timer.function = kvm_bg_timer_expire; vtimer->irq.irq = default_vtimer_irq.irq; ptimer->irq.irq = default_ptimer_irq.irq; @@ -604,7 +604,7 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); - soft_timer_cancel(&timer->timer, &timer->expired); + soft_timer_cancel(&timer->bg_timer, &timer->expired); kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq); } -- cgit v1.2.3 From f2a2129e0ac8d8fa79c3f85425c36f6e3368f022 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Sun, 18 Jun 2017 00:32:08 -0700 Subject: KVM: arm/arm64: Use separate timer for phys timer emulation We were using the same hrtimer for emulating the physical timer and for making sure a blocking VCPU thread would be eventually woken up. That worked fine in the previous arch timer design, but as we are about to actually use the soft timer expire function for the physical timer emulation, change the logic to use a dedicated hrtimer. This has the added benefit of not having to cancel any work in the sync path, which in turn allows us to run the flush and sync with IRQs disabled. Note that the hrtimer used to program the host kernel's timer to generate an exit from the guest when the emulated physical timer fires never has to inject any work, and to share the soft_timer_cancel() function with the bg_timer, we change the function to only cancel any pending work if the pointer to the work struct is not null. Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall --- include/kvm/arm_arch_timer.h | 3 +++ virt/kvm/arm/arch_timer.c | 21 ++++++++++++++++----- 2 files changed, 19 insertions(+), 5 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 0eed5bc9fd5e..184c3ef2df93 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -48,6 +48,9 @@ struct arch_timer_cpu { /* Work queued with the above timer expires */ struct work_struct expired; + /* Physical timer emulation */ + struct hrtimer phys_timer; + /* Is the timer enabled */ bool enabled; }; diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 8ec392850e69..4ad853737c34 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -65,7 +65,8 @@ static void soft_timer_start(struct hrtimer *hrt, u64 ns) static void soft_timer_cancel(struct hrtimer *hrt, struct work_struct *work) { hrtimer_cancel(hrt); - cancel_work_sync(work); + if (work) + cancel_work_sync(work); } static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) @@ -172,6 +173,12 @@ static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt) return HRTIMER_NORESTART; } +static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt) +{ + WARN(1, "Timer only used to ensure guest exit - unexpected event."); + return HRTIMER_NORESTART; +} + bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx) { u64 cval, now; @@ -249,7 +256,7 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) } /* Schedule the background timer for the emulated timer. */ -static void kvm_timer_emulate(struct kvm_vcpu *vcpu, +static void phys_timer_emulate(struct kvm_vcpu *vcpu, struct arch_timer_context *timer_ctx) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; @@ -261,7 +268,7 @@ static void kvm_timer_emulate(struct kvm_vcpu *vcpu, return; /* The timer has not yet expired, schedule a background timer */ - soft_timer_start(&timer->bg_timer, kvm_timer_compute_delta(timer_ctx)); + soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(timer_ctx)); } /* @@ -414,7 +421,7 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) kvm_timer_update_state(vcpu); /* Set the background timer for the physical timer emulation. */ - kvm_timer_emulate(vcpu, vcpu_ptimer(vcpu)); + phys_timer_emulate(vcpu, vcpu_ptimer(vcpu)); if (unlikely(!irqchip_in_kernel(vcpu->kvm))) kvm_timer_flush_hwstate_user(vcpu); @@ -437,7 +444,7 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) * This is to cancel the background timer for the physical timer * emulation if it is set. */ - soft_timer_cancel(&timer->bg_timer, &timer->expired); + soft_timer_cancel(&timer->phys_timer, NULL); /* * The guest could have modified the timer registers or the timer @@ -497,6 +504,9 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) 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; + vtimer->irq.irq = default_vtimer_irq.irq; ptimer->irq.irq = default_ptimer_irq.irq; } @@ -605,6 +615,7 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); soft_timer_cancel(&timer->bg_timer, &timer->expired); + soft_timer_cancel(&timer->phys_timer, NULL); kvm_vgic_unmap_phys_irq(vcpu, vtimer->irq.irq); } -- cgit v1.2.3 From b103cc3f10c06fb81faacd4ee6f88bbd21246073 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Sun, 16 Oct 2016 20:30:38 +0200 Subject: KVM: arm/arm64: Avoid timer save/restore in vcpu entry/exit We don't need to save and restore the hardware timer state and examine if it generates interrupts on on every entry/exit to the guest. The timer hardware is perfectly capable of telling us when it has expired by signaling interrupts. When taking a vtimer interrupt in the host, we don't want to mess with the timer configuration, we just want to forward the physical interrupt to the guest as a virtual interrupt. We can use the split priority drop and deactivate feature of the GIC to do this, which leaves an EOI'ed interrupt active on the physical distributor, making sure we don't keep taking timer interrupts which would prevent the guest from running. We can then forward the physical interrupt to the VM using the HW bit in the LR of the GIC, like we do already, which lets the guest directly deactivate both the physical and virtual timer simultaneously, allowing the timer hardware to exit the VM and generate a new physical interrupt when the timer output is again asserted later on. We do need to capture this state when migrating VCPUs between physical CPUs, however, which we use the vcpu put/load functions for, which are called through preempt notifiers whenever the thread is scheduled away from the CPU or called directly if we return from the ioctl to userspace. One caveat is that we have to save and restore the timer state in both kvm_timer_vcpu_[put/load] and kvm_timer_[schedule/unschedule], because we can have the following flows: 1. kvm_vcpu_block 2. kvm_timer_schedule 3. schedule 4. kvm_timer_vcpu_put (preempt notifier) 5. schedule (vcpu thread gets scheduled back) 6. kvm_timer_vcpu_load (preempt notifier) 7. kvm_timer_unschedule And a version where we don't actually call schedule: 1. kvm_vcpu_block 2. kvm_timer_schedule 7. kvm_timer_unschedule Since kvm_timer_[schedule/unschedule] may not be followed by put/load, but put/load also may be called independently, we call the timer save/restore functions from both paths. Since they rely on the loaded flag to never save/restore when unnecessary, this doesn't cause any harm, and we ensure that all invokations of either set of functions work as intended. An added benefit beyond not having to read and write the timer sysregs on every entry and exit is that we no longer have to actively write the active state to the physical distributor, because we configured the irq for the vtimer to only get a priority drop when handling the interrupt in the GIC driver (we called irq_set_vcpu_affinity()), and the interrupt stays active after firing on the host. Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall --- include/kvm/arm_arch_timer.h | 16 ++- virt/kvm/arm/arch_timer.c | 237 +++++++++++++++++++++++++++---------------- virt/kvm/arm/arm.c | 19 +++- 3 files changed, 178 insertions(+), 94 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 184c3ef2df93..c538f707e1c1 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -31,8 +31,15 @@ struct arch_timer_context { /* Timer IRQ */ struct kvm_irq_level irq; - /* Active IRQ state caching */ - bool active_cleared_last; + /* + * 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; @@ -78,10 +85,15 @@ void kvm_timer_unschedule(struct kvm_vcpu *vcpu); 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); #define vcpu_vtimer(v) (&(v)->arch.timer_cpu.vtimer) #define vcpu_ptimer(v) (&(v)->arch.timer_cpu.ptimer) + +void enable_el1_phys_timer_access(void); +void disable_el1_phys_timer_access(void); + #endif diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index eac1b3d83a86..ec685c1f3b78 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -46,10 +46,9 @@ static const struct kvm_irq_level default_vtimer_irq = { .level = 1, }; -void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) -{ - vcpu_vtimer(vcpu)->active_cleared_last = false; -} +static bool kvm_timer_irq_can_fire(struct arch_timer_context *timer_ctx); +static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, + struct arch_timer_context *timer_ctx); u64 kvm_phys_timer_read(void) { @@ -69,17 +68,45 @@ static void soft_timer_cancel(struct hrtimer *hrt, struct work_struct *work) cancel_work_sync(work); } -static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) +static void kvm_vtimer_update_mask_user(struct kvm_vcpu *vcpu) { - struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id; + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); /* - * We disable the timer in the world switch and let it be - * handled by kvm_timer_sync_hwstate(). Getting a timer - * interrupt at this point is a sure sign of some major - * breakage. + * When using a userspace irqchip with the architected timers, we must + * prevent continuously exiting from the guest, and therefore mask the + * physical interrupt by disabling it on the host interrupt controller + * when the virtual level is high, such that the guest can make + * forward progress. Once we detect the output level being + * de-asserted, we unmask the interrupt again so that we exit from the + * guest when the timer fires. */ - pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu); + if (vtimer->irq.level) + disable_percpu_irq(host_vtimer_irq); + else + enable_percpu_irq(host_vtimer_irq, 0); +} + +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; + + if (!vcpu) { + pr_warn_once("Spurious arch timer IRQ on non-VCPU thread\n"); + return IRQ_NONE; + } + vtimer = vcpu_vtimer(vcpu); + + if (!vtimer->irq.level) { + vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl); + if (kvm_timer_irq_can_fire(vtimer)) + kvm_timer_update_irq(vcpu, true, vtimer); + } + + if (unlikely(!irqchip_in_kernel(vcpu->kvm))) + kvm_vtimer_update_mask_user(vcpu); + return IRQ_HANDLED; } @@ -215,7 +242,6 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, { int ret; - timer_ctx->active_cleared_last = false; timer_ctx->irq.level = new_level; trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_ctx->irq.irq, timer_ctx->irq.level); @@ -271,10 +297,16 @@ static void phys_timer_emulate(struct kvm_vcpu *vcpu, soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(timer_ctx)); } -static void timer_save_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_context *vtimer = vcpu_vtimer(vcpu); + unsigned long flags; + + local_irq_save(flags); + + if (!vtimer->loaded) + goto out; if (timer->enabled) { vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl); @@ -283,6 +315,10 @@ static void timer_save_state(struct kvm_vcpu *vcpu) /* Disable the virtual timer */ write_sysreg_el0(0, cntv_ctl); + + vtimer->loaded = false; +out: + local_irq_restore(flags); } /* @@ -296,6 +332,8 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); + vtimer_save_state(vcpu); + /* * No need to schedule a background timer if any guest timer has * already expired, because kvm_vcpu_block will return before putting @@ -318,22 +356,34 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) soft_timer_start(&timer->bg_timer, kvm_timer_earliest_exp(vcpu)); } -static void timer_restore_state(struct kvm_vcpu *vcpu) +static void vtimer_restore_state(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + unsigned long flags; + + local_irq_save(flags); + + if (vtimer->loaded) + goto out; if (timer->enabled) { write_sysreg_el0(vtimer->cnt_cval, cntv_cval); isb(); write_sysreg_el0(vtimer->cnt_ctl, cntv_ctl); } + + vtimer->loaded = true; +out: + local_irq_restore(flags); } void kvm_timer_unschedule(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + vtimer_restore_state(vcpu); + soft_timer_cancel(&timer->bg_timer, &timer->expired); } @@ -352,61 +402,45 @@ static void set_cntvoff(u64 cntvoff) kvm_call_hyp(__kvm_timer_set_cntvoff, low, high); } -static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu) +static void kvm_timer_vcpu_load_vgic(struct kvm_vcpu *vcpu) { struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); bool phys_active; int ret; - /* - * If we enter the guest with the virtual input level to the VGIC - * asserted, then we have already told the VGIC what we need to, and - * we don't need to exit from the guest until the guest deactivates - * the already injected interrupt, so therefore we should set the - * hardware active state to prevent unnecessary exits from the guest. - * - * Also, if we enter the guest with the virtual timer interrupt active, - * then it must be active on the physical distributor, because we set - * the HW bit and the guest must be able to deactivate the virtual and - * physical interrupt at the same time. - * - * Conversely, if the virtual input level is deasserted and the virtual - * interrupt is not active, then always clear the hardware active state - * to ensure that hardware interrupts from the timer triggers a guest - * exit. - */ phys_active = vtimer->irq.level || - kvm_vgic_map_is_active(vcpu, vtimer->irq.irq); - - /* - * We want to avoid hitting the (re)distributor as much as - * possible, as this is a potentially expensive MMIO access - * (not to mention locks in the irq layer), and a solution for - * this is to cache the "active" state in memory. - * - * Things to consider: we cannot cache an "active set" state, - * because the HW can change this behind our back (it becomes - * "clear" in the HW). We must then restrict the caching to - * the "clear" state. - * - * The cache is invalidated on: - * - vcpu put, indicating that the HW cannot be trusted to be - * in a sane state on the next vcpu load, - * - any change in the interrupt state - * - * Usage conditions: - * - cached value is "active clear" - * - value to be programmed is "active clear" - */ - if (vtimer->active_cleared_last && !phys_active) - return; + kvm_vgic_map_is_active(vcpu, vtimer->irq.irq); ret = irq_set_irqchip_state(host_vtimer_irq, IRQCHIP_STATE_ACTIVE, phys_active); WARN_ON(ret); +} - vtimer->active_cleared_last = !phys_active; +static void kvm_timer_vcpu_load_user(struct kvm_vcpu *vcpu) +{ + kvm_vtimer_update_mask_user(vcpu); +} + +void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + + if (unlikely(!timer->enabled)) + return; + + if (unlikely(!irqchip_in_kernel(vcpu->kvm))) + kvm_timer_vcpu_load_user(vcpu); + else + kvm_timer_vcpu_load_vgic(vcpu); + + set_cntvoff(vtimer->cntvoff); + + vtimer_restore_state(vcpu); + + if (has_vhe()) + disable_el1_phys_timer_access(); } bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) @@ -426,23 +460,6 @@ bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) ptimer->irq.level != plevel; } -static void kvm_timer_flush_hwstate_user(struct kvm_vcpu *vcpu) -{ - struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); - - /* - * To prevent continuously exiting from the guest, we mask the - * physical interrupt such that the guest can make forward progress. - * Once we detect the output level being deasserted, we unmask the - * interrupt again so that we exit from the guest when the timer - * fires. - */ - if (vtimer->irq.level) - disable_percpu_irq(host_vtimer_irq); - else - enable_percpu_irq(host_vtimer_irq, 0); -} - /** * kvm_timer_flush_hwstate - prepare timers before running the vcpu * @vcpu: The vcpu pointer @@ -455,23 +472,61 @@ static void kvm_timer_flush_hwstate_user(struct kvm_vcpu *vcpu) void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); if (unlikely(!timer->enabled)) return; - kvm_timer_update_state(vcpu); + if (kvm_timer_should_fire(ptimer) != ptimer->irq.level) + kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer); /* Set the background timer for the physical timer emulation. */ phys_timer_emulate(vcpu, vcpu_ptimer(vcpu)); +} - if (unlikely(!irqchip_in_kernel(vcpu->kvm))) - kvm_timer_flush_hwstate_user(vcpu); - else - kvm_timer_flush_hwstate_vgic(vcpu); +void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - set_cntvoff(vtimer->cntvoff); - timer_restore_state(vcpu); + if (unlikely(!timer->enabled)) + return; + + if (has_vhe()) + enable_el1_phys_timer_access(); + + vtimer_save_state(vcpu); + + /* + * The kernel may decide to run userspace after calling vcpu_put, so + * we reset cntvoff to 0 to ensure a consistent read between user + * accesses to the virtual counter and kernel access to the physical + * counter. + */ + set_cntvoff(0); +} + +static void unmask_vtimer_irq(struct kvm_vcpu *vcpu) +{ + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + + if (unlikely(!irqchip_in_kernel(vcpu->kvm))) { + kvm_vtimer_update_mask_user(vcpu); + return; + } + + /* + * If the guest disabled the timer without acking the interrupt, then + * we must make sure the physical and virtual active states are in + * sync by deactivating the physical interrupt, because otherwise we + * wouldn't see the next timer interrupt in the host. + */ + if (!kvm_vgic_map_is_active(vcpu, vtimer->irq.irq)) { + int ret; + ret = irq_set_irqchip_state(host_vtimer_irq, + IRQCHIP_STATE_ACTIVE, + false); + WARN_ON(ret); + } } /** @@ -484,6 +539,7 @@ void kvm_timer_flush_hwstate(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_context *vtimer = vcpu_vtimer(vcpu); /* * This is to cancel the background timer for the physical timer @@ -491,14 +547,19 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) */ soft_timer_cancel(&timer->phys_timer, NULL); - timer_save_state(vcpu); - set_cntvoff(0); - /* - * The guest could have modified the timer registers or the timer - * could have expired, update the timer state. + * If we entered the guest with the vtimer output asserted we have to + * check if the guest has modified the timer so that we should lower + * the line at this point. */ - kvm_timer_update_state(vcpu); + if (vtimer->irq.level) { + vtimer->cnt_ctl = read_sysreg_el0(cntv_ctl); + vtimer->cnt_cval = read_sysreg_el0(cntv_cval); + if (!kvm_timer_should_fire(vtimer)) { + kvm_timer_update_irq(vcpu, false, vtimer); + unmask_vtimer_irq(vcpu); + } + } } int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu) diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 27db222a0c8d..132d39ae13d2 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -354,18 +354,18 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vcpu->arch.host_cpu_context = this_cpu_ptr(kvm_host_cpu_state); kvm_arm_set_running_vcpu(vcpu); - kvm_vgic_load(vcpu); + kvm_timer_vcpu_load(vcpu); } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) { + kvm_timer_vcpu_put(vcpu); kvm_vgic_put(vcpu); vcpu->cpu = -1; kvm_arm_set_running_vcpu(NULL); - kvm_timer_vcpu_put(vcpu); } static void vcpu_power_off(struct kvm_vcpu *vcpu) @@ -710,15 +710,26 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) kvm_arm_clear_debug(vcpu); /* - * We must sync the PMU and timer state before the vgic state so + * We must sync the PMU state before the vgic state so * that the vgic can properly sample the updated state of the * interrupt line. */ kvm_pmu_sync_hwstate(vcpu); - kvm_timer_sync_hwstate(vcpu); + /* + * Sync the vgic state before syncing the timer state because + * the timer code needs to know if the virtual timer + * interrupts are active. + */ kvm_vgic_sync_hwstate(vcpu); + /* + * Sync the timer hardware state before enabling interrupts as + * we don't want vtimer interrupts to race with syncing the + * timer virtual interrupt state. + */ + kvm_timer_sync_hwstate(vcpu); + /* * We may have taken a host interrupt in HYP mode (ie * while executing the guest). This interrupt is still -- cgit v1.2.3 From 7e90c8e5704cbb299d48e7debb1e61614cb12f41 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Tue, 20 Jun 2017 07:56:20 -0700 Subject: KVM: arm/arm64: Get rid of kvm_timer_flush_hwstate Now when both the vtimer and the ptimer when using both the in-kernel vgic emulation and a userspace IRQ chip are driven by the timer signals and at the vcpu load/put boundaries, instead of recomputing the timer state at every entry/exit to/from the guest, we can get entirely rid of the flush hwstate function. Signed-off-by: Christoffer Dall Acked-by: Marc Zyngier --- include/kvm/arm_arch_timer.h | 1 - virt/kvm/arm/arch_timer.c | 24 ------------------------ virt/kvm/arm/arm.c | 1 - 3 files changed, 26 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index c538f707e1c1..2352f3a4e88b 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -66,7 +66,6 @@ int kvm_timer_hyp_init(void); int kvm_timer_enable(struct kvm_vcpu *vcpu); int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu); -void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu); void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu); bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu); void kvm_timer_update_run(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 20e56c420632..53d9bd4a734f 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -305,12 +305,6 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); - /* - * If userspace modified the timer registers via SET_ONE_REG before - * the vgic was initialized, we mustn't set the vtimer->irq.level value - * because the guest would never see the interrupt. Instead wait - * until we call this function from kvm_timer_flush_hwstate. - */ if (unlikely(!timer->enabled)) return; @@ -489,24 +483,6 @@ bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) ptimer->irq.level != plevel; } -/** - * kvm_timer_flush_hwstate - prepare timers before running the vcpu - * @vcpu: The vcpu pointer - * - * Check if the virtual timer has expired while we were running in the host, - * and inject an interrupt if that was the case, making sure the timer is - * masked or disabled on the host so that we keep executing. Also schedule a - * software timer for the physical timer if it is enabled. - */ -void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) -{ - struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); - - if (unlikely(!timer->enabled)) - return; -} - void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 132d39ae13d2..14c50d142c67 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -656,7 +656,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) local_irq_disable(); - kvm_timer_flush_hwstate(vcpu); kvm_vgic_flush_hwstate(vcpu); /* -- cgit v1.2.3 From 1c88ab7ec8c53c4d806bb2b6871ddafdebbffa8b Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Fri, 6 Jan 2017 16:07:48 +0100 Subject: KVM: arm/arm64: Rework kvm_timer_should_fire kvm_timer_should_fire() can be called in two different situations from the kvm_vcpu_block(). The first case is before calling kvm_timer_schedule(), used for wait polling, and in this case the VCPU thread is running and the timer state is loaded onto the hardware so all we have to do is check if the virtual interrupt lines are asserted, becasue the timer interrupt handler functions will raise those lines as appropriate. The second case is inside the wait loop of kvm_vcpu_block(), where we have already called kvm_timer_schedule() and therefore the hardware will be disabled and the software view of the timer state is up to date (timer->loaded is false), and so we can simply check if the timer should fire by looking at the software state. Signed-off-by: Christoffer Dall Reviewed-by: Marc Zyngier --- include/kvm/arm_arch_timer.h | 3 ++- virt/kvm/arm/arch_timer.c | 22 +++++++++++++++++++++- virt/kvm/arm/arm.c | 3 +-- 3 files changed, 24 insertions(+), 4 deletions(-) (limited to 'include/kvm/arm_arch_timer.h') diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 2352f3a4e88b..01ee473517e2 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -78,7 +78,8 @@ int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); -bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx); +bool kvm_timer_is_pending(struct kvm_vcpu *vcpu); + void kvm_timer_schedule(struct kvm_vcpu *vcpu); void kvm_timer_unschedule(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 53d9bd4a734f..2035cf251701 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -49,6 +49,7 @@ static const struct kvm_irq_level default_vtimer_irq = { static bool kvm_timer_irq_can_fire(struct arch_timer_context *timer_ctx); static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, struct arch_timer_context *timer_ctx); +static bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx); u64 kvm_phys_timer_read(void) { @@ -226,7 +227,7 @@ static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt) return HRTIMER_NORESTART; } -bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx) +static bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx) { u64 cval, now; @@ -239,6 +240,25 @@ bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx) return cval <= now; } +bool kvm_timer_is_pending(struct kvm_vcpu *vcpu) +{ + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); + + if (vtimer->irq.level || ptimer->irq.level) + return true; + + /* + * When this is called from withing the wait loop of kvm_vcpu_block(), + * the software view of the timer state is up to date (timer->loaded + * is false), and so we can simply check if the timer should fire now. + */ + if (!vtimer->loaded && kvm_timer_should_fire(vtimer)) + return true; + + return kvm_timer_should_fire(ptimer); +} + /* * Reflect the timer output level into the kvm_run structure */ diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 14c50d142c67..bc126fb99a3d 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -307,8 +307,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) { - return kvm_timer_should_fire(vcpu_vtimer(vcpu)) || - kvm_timer_should_fire(vcpu_ptimer(vcpu)); + return kvm_timer_is_pending(vcpu); } void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) -- cgit v1.2.3