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Programming the active state in the (re)distributor can be an expensive operation so it makes some sense to try and reduce the number of accesses as much as possible. So far, we program the active state on each VM entry, but there is some opportunity to do less. An obvious solution is to cache the active state in memory, and only program it in the HW when conditions change. But because the HW can also change things under our feet (the active state can transition from 1 to 0 when the guest does an EOI), some precautions have to be taken, which amount to only caching an "inactive" state, and always programing it otherwise. With this in place, we observe a reduction of around 700 cycles on a 2GHz GICv2 platform for a NULL hypercall. Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
83 lines
2.3 KiB
C
83 lines
2.3 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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/* Active IRQ state caching */
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bool active_cleared_last;
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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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void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu);
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#endif
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