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4b4b4512da
The arch timer currently uses edge-triggered semantics in the sense that the line is never sampled by the vgic and lowering the line from the timer to the vgic doesn't have any effect on the pending state of virtual interrupts in the vgic. This means that we do not support a guest with the otherwise valid behavior of (1) disable interrupts (2) enable the timer (3) disable the timer (4) enable interrupts. Such a guest would validly not expect to see any interrupts on real hardware, but will see interrupts on KVM. This patch fixes this shortcoming through the following series of changes. First, we change the flow of the timer/vgic sync/flush operations. Now the timer is always flushed/synced before the vgic, because the vgic samples the state of the timer output. This has the implication that we move the timer operations in to non-preempible sections, but that is fine after the previous commit getting rid of hrtimer schedules on every entry/exit. Second, we change the internal behavior of the timer, letting the timer keep track of its previous output state, and only lower/raise the line to the vgic when the state changes. Note that in theory this could have been accomplished more simply by signalling the vgic every time the state *potentially* changed, but we don't want to be hitting the vgic more often than necessary. Third, we get rid of the use of the map->active field in the vgic and instead simply set the interrupt as active on the physical distributor whenever the input to the GIC is asserted and conversely clear the physical active state when the input to the GIC is deasserted. Fourth, and finally, we now initialize the timer PPIs (and all the other unused PPIs for now), to be level-triggered, and modify the sync code to sample the line state on HW sync and re-inject a new interrupt if it is still pending at that time. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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* Author: Marc Zyngier <marc.zyngier@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef __ASM_ARM_KVM_ARCH_TIMER_H
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#define __ASM_ARM_KVM_ARCH_TIMER_H
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#include <linux/clocksource.h>
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#include <linux/hrtimer.h>
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#include <linux/workqueue.h>
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struct arch_timer_kvm {
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/* Is the timer enabled */
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bool enabled;
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/* Virtual offset */
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cycle_t cntvoff;
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};
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struct arch_timer_cpu {
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/* Registers: control register, timer value */
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u32 cntv_ctl; /* Saved/restored */
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cycle_t cntv_cval; /* Saved/restored */
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/*
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* Anything that is not used directly from assembly code goes
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* here.
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*/
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/* Background timer used when the guest is not running */
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struct hrtimer timer;
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/* Work queued with the above timer expires */
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struct work_struct expired;
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/* Background timer active */
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bool armed;
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/* Timer IRQ */
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struct kvm_irq_level irq;
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/* VGIC mapping */
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struct irq_phys_map *map;
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};
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int kvm_timer_hyp_init(void);
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void kvm_timer_enable(struct kvm *kvm);
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void kvm_timer_init(struct kvm *kvm);
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int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
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const struct kvm_irq_level *irq);
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void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
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void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
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void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
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void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu);
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u64 kvm_arm_timer_get_reg(struct kvm_vcpu *, u64 regid);
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int kvm_arm_timer_set_reg(struct kvm_vcpu *, u64 regid, u64 value);
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bool kvm_timer_should_fire(struct kvm_vcpu *vcpu);
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void kvm_timer_schedule(struct kvm_vcpu *vcpu);
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void kvm_timer_unschedule(struct kvm_vcpu *vcpu);
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#endif
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