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arm/arm64: KVM: Require in-kernel vgic for the arch timers

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It is curently possible to run a VM with architected timers support
without creating an in-kernel VGIC, which will result in interrupts from
the virtual timer going nowhere.

To address this issue, move the architected timers initialization to the
time when we run a VCPU for the first time, and then only initialize
(and enable) the architected timers if we have a properly created and
initialized in-kernel VGIC.

When injecting interrupts from the virtual timer to the vgic, the
current setup should ensure that this never calls an on-demand init of
the VGIC, which is the only call path that could return an error from
kvm_vgic_inject_irq(), so capture the return value and raise a warning
if there's an error there.

We also change the kvm_timer_init() function from returning an int to be
a void function, since the function always succeeds.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Christoffer Dall 2014-12-12 21:19:23 +01:00
parent ca7d9c829d
commit 05971120fc
3 changed files with 38 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
arch/arm/kvm/arm.c
View file

@ -425,6 +425,7 @@ static void update_vttbr(struct kvm *kvm)
static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
int ret;
if (likely(vcpu->arch.has_run_once))
@ -436,12 +437,20 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
* Map the VGIC hardware resources before running a vcpu the first
* time on this VM.
*/
if (unlikely(!vgic_ready(vcpu->kvm))) {
ret = kvm_vgic_map_resources(vcpu->kvm);
if (unlikely(!vgic_ready(kvm))) {
ret = kvm_vgic_map_resources(kvm);
if (ret)
return ret;
}
/*
* Enable the arch timers only if we have an in-kernel VGIC
* and it has been properly initialized, since we cannot handle
* interrupts from the virtual timer with a userspace gic.
*/
if (irqchip_in_kernel(kvm) && vgic_initialized(kvm))
kvm_timer_enable(kvm);
return 0;
}

10
include/kvm/arm_arch_timer.h
View file

@ -60,7 +60,8 @@ struct arch_timer_cpu {
#ifdef CONFIG_KVM_ARM_TIMER
int kvm_timer_hyp_init(void);
int kvm_timer_init(struct kvm *kvm);
void kvm_timer_enable(struct kvm *kvm);
void kvm_timer_init(struct kvm *kvm);
void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
const struct kvm_irq_level *irq);
void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
@ -77,11 +78,8 @@ 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_enable(struct kvm *kvm) {}
static inline void kvm_timer_init(struct kvm *kvm) {}
static inline void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
const struct kvm_irq_level *irq) {}
static inline void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) {}

32
virt/kvm/arm/arch_timer.c
View file

@ -61,12 +61,14 @@ static void timer_disarm(struct arch_timer_cpu *timer)
static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
{
int ret;
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
timer->irq->irq,
timer->irq->level);
ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
timer->irq->irq,
timer->irq->level);
WARN_ON(ret);
}
static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
@ -307,12 +309,24 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
timer_disarm(timer);
}
int kvm_timer_init(struct kvm *kvm)
void kvm_timer_enable(struct kvm *kvm)
{
if (timecounter && wqueue) {
kvm->arch.timer.cntvoff = kvm_phys_timer_read();
kvm->arch.timer.enabled = 1;
}
if (kvm->arch.timer.enabled)
return;
return 0;
/*
* There is a potential race here between VCPUs starting for the first
* time, which may be enabling the timer multiple times. That doesn't
* hurt though, because we're just setting a variable to the same
* variable that it already was. The important thing is that all
* VCPUs have the enabled variable set, before entering the guest, if
* the arch timers are enabled.
*/
if (timecounter && wqueue)
kvm->arch.timer.enabled = 1;
}
void kvm_timer_init(struct kvm *kvm)
{
kvm->arch.timer.cntvoff = kvm_phys_timer_read();
}