ARM: KVM: arch_timers: Add guest timer core support

Add some the architected timer related infrastructure, and support timer
interrupt injection, which can happen as a resultof three possible
events:

- The virtual timer interrupt has fired while we were still
  executing the guest
- The timer interrupt hasn't fired, but it expired while we
  were doing the world switch
- A hrtimer we programmed earlier has fired

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2013-01-23 13:21:58 -05:00
parent 9ae9e2535d
commit 53e724067a
5 changed files with 394 additions and 0 deletions

View File

@ -0,0 +1,85 @@
/*
* Copyright (C) 2012 ARM Ltd.
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __ASM_ARM_KVM_ARCH_TIMER_H
#define __ASM_ARM_KVM_ARCH_TIMER_H
#include <linux/clocksource.h>
#include <linux/hrtimer.h>
#include <linux/workqueue.h>
struct arch_timer_kvm {
#ifdef CONFIG_KVM_ARM_TIMER
/* Is the timer enabled */
bool enabled;
/* Virtual offset */
cycle_t cntvoff;
#endif
};
struct arch_timer_cpu {
#ifdef CONFIG_KVM_ARM_TIMER
/* Registers: control register, timer value */
u32 cntv_ctl; /* Saved/restored */
cycle_t cntv_cval; /* Saved/restored */
/*
* Anything that is not used directly from assembly code goes
* here.
*/
/* Background timer used when the guest is not running */
struct hrtimer timer;
/* Work queued with the above timer expires */
struct work_struct expired;
/* Background timer active */
bool armed;
/* Timer IRQ */
const struct kvm_irq_level *irq;
#endif
};
#ifdef CONFIG_KVM_ARM_TIMER
int kvm_timer_hyp_init(void);
int kvm_timer_init(struct kvm *kvm);
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);
void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu);
#else
static inline int kvm_timer_hyp_init(void)
{
return 0;
};
static inline int kvm_timer_init(struct kvm *kvm)
{
return 0;
}
static inline void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) {}
static inline void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) {}
static inline void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) {}
static inline void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu) {}
#endif
#endif

View File

@ -23,6 +23,7 @@
#include <asm/kvm_asm.h>
#include <asm/kvm_mmio.h>
#include <asm/fpstate.h>
#include <asm/kvm_arch_timer.h>
#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS
#define KVM_MEMORY_SLOTS 32
@ -49,6 +50,9 @@ struct kvm_arch {
/* VTTBR value associated with below pgd and vmid */
u64 vttbr;
/* Timer */
struct arch_timer_kvm timer;
/*
* Anything that is not used directly from assembly code goes
* here.
@ -99,6 +103,7 @@ struct kvm_vcpu_arch {
/* VGIC state */
struct vgic_cpu vgic_cpu;
struct arch_timer_cpu timer_cpu;
/*
* Anything that is not used directly from assembly code goes

271
arch/arm/kvm/arch_timer.c Normal file
View File

@ -0,0 +1,271 @@
/*
* Copyright (C) 2012 ARM Ltd.
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/cpu.h>
#include <linux/of_irq.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/interrupt.h>
#include <asm/arch_timer.h>
#include <asm/kvm_vgic.h>
#include <asm/kvm_arch_timer.h>
static struct timecounter *timecounter;
static struct workqueue_struct *wqueue;
static struct kvm_irq_level timer_irq = {
.level = 1,
};
static cycle_t kvm_phys_timer_read(void)
{
return timecounter->cc->read(timecounter->cc);
}
static bool timer_is_armed(struct arch_timer_cpu *timer)
{
return timer->armed;
}
/* timer_arm: as in "arm the timer", not as in ARM the company */
static void timer_arm(struct arch_timer_cpu *timer, u64 ns)
{
timer->armed = true;
hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns),
HRTIMER_MODE_ABS);
}
static void timer_disarm(struct arch_timer_cpu *timer)
{
if (timer_is_armed(timer)) {
hrtimer_cancel(&timer->timer);
cancel_work_sync(&timer->expired);
timer->armed = false;
}
}
static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
timer->cntv_ctl |= 1 << 1; /* Mask the interrupt in the guest */
kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
vcpu->arch.timer_cpu.irq->irq,
vcpu->arch.timer_cpu.irq->level);
}
static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
{
struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
/*
* 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.
*/
pr_warn("Unexpected interrupt %d on vcpu %p\n", irq, vcpu);
return IRQ_HANDLED;
}
static void kvm_timer_inject_irq_work(struct work_struct *work)
{
struct kvm_vcpu *vcpu;
vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
vcpu->arch.timer_cpu.armed = false;
kvm_timer_inject_irq(vcpu);
}
static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
{
struct arch_timer_cpu *timer;
timer = container_of(hrt, struct arch_timer_cpu, timer);
queue_work(wqueue, &timer->expired);
return HRTIMER_NORESTART;
}
/**
* kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
* @vcpu: The vcpu pointer
*
* Disarm any pending soft timers, since the world-switch code will write the
* virtual timer state back to the physical CPU.
*/
void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
/*
* We're about to run this vcpu again, so there is no need to
* keep the background timer running, as we're about to
* populate the CPU timer again.
*/
timer_disarm(timer);
}
/**
* kvm_timer_sync_hwstate - sync timer state from cpu
* @vcpu: The vcpu pointer
*
* Check if the virtual timer was armed and either schedule a corresponding
* soft timer or inject directly if already expired.
*/
void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
cycle_t cval, now;
u64 ns;
/* Check if the timer is enabled and unmasked first */
if ((timer->cntv_ctl & 3) != 1)
return;
cval = timer->cntv_cval;
now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
BUG_ON(timer_is_armed(timer));
if (cval <= now) {
/*
* Timer has already expired while we were not
* looking. Inject the interrupt and carry on.
*/
kvm_timer_inject_irq(vcpu);
return;
}
ns = cyclecounter_cyc2ns(timecounter->cc, cval - now);
timer_arm(timer, ns);
}
void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
timer->timer.function = kvm_timer_expire;
timer->irq = &timer_irq;
}
static void kvm_timer_init_interrupt(void *info)
{
enable_percpu_irq(timer_irq.irq, 0);
}
static int kvm_timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *cpu)
{
switch (action) {
case CPU_STARTING:
case CPU_STARTING_FROZEN:
kvm_timer_init_interrupt(NULL);
break;
case CPU_DYING:
case CPU_DYING_FROZEN:
disable_percpu_irq(timer_irq.irq);
break;
}
return NOTIFY_OK;
}
static struct notifier_block kvm_timer_cpu_nb = {
.notifier_call = kvm_timer_cpu_notify,
};
static const struct of_device_id arch_timer_of_match[] = {
{ .compatible = "arm,armv7-timer", },
{},
};
int kvm_timer_hyp_init(void)
{
struct device_node *np;
unsigned int ppi;
int err;
timecounter = arch_timer_get_timecounter();
if (!timecounter)
return -ENODEV;
np = of_find_matching_node(NULL, arch_timer_of_match);
if (!np) {
kvm_err("kvm_arch_timer: can't find DT node\n");
return -ENODEV;
}
ppi = irq_of_parse_and_map(np, 2);
if (!ppi) {
kvm_err("kvm_arch_timer: no virtual timer interrupt\n");
err = -EINVAL;
goto out;
}
err = request_percpu_irq(ppi, kvm_arch_timer_handler,
"kvm guest timer", kvm_get_running_vcpus());
if (err) {
kvm_err("kvm_arch_timer: can't request interrupt %d (%d)\n",
ppi, err);
goto out;
}
timer_irq.irq = ppi;
err = register_cpu_notifier(&kvm_timer_cpu_nb);
if (err) {
kvm_err("Cannot register timer CPU notifier\n");
goto out_free;
}
wqueue = create_singlethread_workqueue("kvm_arch_timer");
if (!wqueue) {
err = -ENOMEM;
goto out_free;
}
kvm_info("%s IRQ%d\n", np->name, ppi);
on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
goto out;
out_free:
free_percpu_irq(ppi, kvm_get_running_vcpus());
out:
of_node_put(np);
return err;
}
void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
timer_disarm(timer);
}
int kvm_timer_init(struct kvm *kvm)
{
if (timecounter && wqueue) {
kvm->arch.timer.cntvoff = kvm_phys_timer_read();
kvm->arch.timer.enabled = 1;
}
return 0;
}

View File

@ -95,6 +95,7 @@ ENTRY(__kvm_vcpu_run)
save_host_regs
restore_vgic_state
restore_timer_state
@ Store hardware CP15 state and load guest state
read_cp15_state store_to_vcpu = 0
@ -189,6 +190,7 @@ after_vfp_restore:
read_cp15_state store_to_vcpu = 1
write_cp15_state read_from_vcpu = 0
save_timer_state
save_vgic_state
restore_host_regs

View File

@ -453,6 +453,37 @@ vcpu .req r0 @ vcpu pointer always in r0
#endif
.endm
#define CNTHCTL_PL1PCTEN (1 << 0)
#define CNTHCTL_PL1PCEN (1 << 1)
/*
* Save the timer state onto the VCPU and allow physical timer/counter access
* for the host.
*
* Assumes vcpu pointer in vcpu reg
*/
.macro save_timer_state
@ Allow physical timer/counter access for the host
mrc p15, 4, r2, c14, c1, 0 @ CNTHCTL
orr r2, r2, #(CNTHCTL_PL1PCEN | CNTHCTL_PL1PCTEN)
mcr p15, 4, r2, c14, c1, 0 @ CNTHCTL
.endm
/*
* Load the timer state from the VCPU and deny physical timer/counter access
* for the host.
*
* Assumes vcpu pointer in vcpu reg
*/
.macro restore_timer_state
@ Disallow physical timer access for the guest
@ Physical counter access is allowed
mrc p15, 4, r2, c14, c1, 0 @ CNTHCTL
orr r2, r2, #CNTHCTL_PL1PCTEN
bic r2, r2, #CNTHCTL_PL1PCEN
mcr p15, 4, r2, c14, c1, 0 @ CNTHCTL
.endm
.equ vmentry, 0
.equ vmexit, 1