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().
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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