On Mon, Aug 20, 2012 at 5:26 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
> On 18/08/12 03:58, Christoffer Dall wrote:
>> On Thu, Jul 5, 2012 at 11:28 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>>> When an interrupt occurs for the guest, it is sometimes necessary
>>> to find out which vcpu was running at that point.
>>
>> s/was/is/ ?
>>
>>>
>>> Keep track of which vcpu is being tun in kvm_arch_vcpu_ioctl_run(),
>>
>> s/tun/run/
>>
>>> and allow the data to be retrived using either:
>>> - kvm_arm_get_running_vcpu(): returns the vcpu running at this point
>>> on the current CPU. Can only be used in a non-preemptable context.
>>
>> was last run you mean - if you can call this function it's not run,
>> strictly speaking
>>
>> or just say: the vcpu loaded at this point, eh maybe not.
>>
>>> - kvm_arm_get_running_vcpus(): returns the per-CPU variable holding
>>> the the running vcpus, useable for per-CPU interrupts.
>>>
>>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>>> ---
>>> arch/arm/include/asm/kvm_host.h | 3 +++
>>> arch/arm/kvm/arm.c | 29 +++++++++++++++++++++++++++++
>>> 2 files changed, 32 insertions(+)
>>>
>>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>>> index 9d0cc83..91be029 100644
>>> --- a/arch/arm/include/asm/kvm_host.h
>>> +++ b/arch/arm/include/asm/kvm_host.h
>>> @@ -156,4 +156,7 @@ static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
>>> return 0;
>>> }
>>>
>>> +struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>>> +struct kvm_vcpu __percpu **kvm_get_running_vcpus(void);
>>> +
>>> #endif /* __ARM_KVM_HOST_H__ */
>>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>>> index 44691e1..8bb53cb 100644
>>> --- a/arch/arm/kvm/arm.c
>>> +++ b/arch/arm/kvm/arm.c
>>> @@ -46,11 +46,38 @@
>>>
>>> static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
>>>
>>> +/* Per-CPU variable containing the currently running vcpu. */
>>> +static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_arm_running_vcpu);
>>> +
>>> /* The VMID used in the VTTBR */
>>> static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
>>> static u8 kvm_next_vmid;
>>> DEFINE_SPINLOCK(kvm_vmid_lock);
>>>
>>> +static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
>>> +{
>>> + BUG_ON(preemptible());
>>> + __get_cpu_var(kvm_arm_running_vcpu) = vcpu;
>>> +}
>>> +
>>> +/**
>>> + * kvm_arm_get_running_vcpu - get the vcpu running on the current CPU.
>>> + * Must be called from non-preemptible context
>>> + */
>>> +struct kvm_vcpu *kvm_arm_get_running_vcpu(void)
>>> +{
>>> + BUG_ON(preemptible());
>>> + return __get_cpu_var(kvm_arm_running_vcpu);
>>> +}
>>> +
>>> +/**
>>> + * kvm_arm_get_running_vcpus - get the per-CPU array on currently running vcpus.
>>> + */
>>> +struct kvm_vcpu __percpu **kvm_get_running_vcpus(void)
>>> +{
>>> + return &kvm_arm_running_vcpu;
>>> +}
>>> +
>>> int kvm_arch_hardware_enable(void *garbage)
>>> {
>>> return 0;
>>> @@ -576,9 +603,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>>> trace_kvm_entry(vcpu->arch.regs.pc);
>>> kvm_guest_enter();
>>> vcpu->mode = IN_GUEST_MODE;
>>> + kvm_arm_set_running_vcpu(vcpu);
>>>
>>> ret = __kvm_vcpu_run(vcpu);
>>>
>>> + kvm_arm_set_running_vcpu(NULL);
>>
>> this made your function quite useless, but I guess you know that
>> because of the fixup you posted :)
>
> Useless? If you put that back in the context of how the code was
> structured two months ago (circa v9), it makes a lot more sense.
> Interrupts would have already been dealt with before returning from
> __kvm_vcpu_run().
>
that's true. My bad.
> These days, this code has been moved to kvm_arch_vcpu_load() and
> kvm_arch_vcpu_put().
>
>> with the fixup it all looks ok to me.
>>
>>> vcpu->mode = OUTSIDE_GUEST_MODE;
>>> vcpu->stat.exits++;
>>> kvm_guest_exit();
>>> --
>>> 1.7.10.3
>>>
>>>
>>
>
>
> --
> Jazz is not dead. It just smells funny...
>
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