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 :)
with the fixup it all looks ok to me.
> vcpu->mode = OUTSIDE_GUEST_MODE;
> vcpu->stat.exits++;
> kvm_guest_exit();
> --
> 1.7.10.3
>
>
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