Re: [PATCH v2] KVM: Factor out kvm_vcpu_kick to arch-generic code

[Marcelo Tosatti <mtosatti@redhat.com>]

On Tue, Jan 24, 2012 at 11:27:39PM -0500, Christoffer Dall wrote:
> The kvm_vcpu_kick function performs roughly the same funcitonality on
> most all architectures, so we shouldn't have separate copies.
> 
> PowerPC keeps a pointer to interchanging waitqueues on the vcpu_arch
> structure and to accomodate this special need a
> __KVM_HAVE_ARCH_VCPU_GET_WQ define and accompanying function
> kvm_arch_vcpu_wq have been defined. For all other architectures this
> is a generic inline that just returns &vcpu->wq;
> 
> This patch applies to Linus' tree on the Linux 3.3-rc1 tag.
> 
> Changes since v1:
>  - Abstact CPU mode check into arch-specific function
>  - Remove redundant vcpu->cpu assignment
> 
> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
> ---
>  arch/ia64/include/asm/kvm_host.h    |    1 +
>  arch/ia64/kvm/kvm-ia64.c            |   16 ----------------
>  arch/powerpc/include/asm/kvm_host.h |    6 ++++++
>  arch/powerpc/kvm/powerpc.c          |   18 +++++++-----------
>  arch/s390/kvm/kvm-s390.c            |    8 ++++++++
>  arch/x86/kvm/x86.c                  |   17 ++---------------
>  include/linux/kvm_host.h            |    9 +++++++++
>  virt/kvm/kvm_main.c                 |   23 +++++++++++++++++++++++
>  8 files changed, 56 insertions(+), 42 deletions(-)
> 
> diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
> index 2689ee5..06a5e91 100644
> --- a/arch/ia64/include/asm/kvm_host.h
> +++ b/arch/ia64/include/asm/kvm_host.h
> @@ -365,6 +365,7 @@ struct thash_cb {
>  };
>  
>  struct kvm_vcpu_stat {
> +	u32 halt_wakeup;
>  };
>  
>  struct kvm_vcpu_arch {
> diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
> index 43f4c92..428eb0b 100644
> --- a/arch/ia64/kvm/kvm-ia64.c
> +++ b/arch/ia64/kvm/kvm-ia64.c
> @@ -1402,7 +1402,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  {
>  	if (cpu != vcpu->cpu) {
> -		vcpu->cpu = cpu;
>  		if (vcpu->arch.ht_active)
>  			kvm_migrate_hlt_timer(vcpu);
>  	}
> @@ -1851,21 +1850,6 @@ void kvm_arch_hardware_unsetup(void)
>  {
>  }
>  
> -void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
> -{
> -	int me;
> -	int cpu = vcpu->cpu;
> -
> -	if (waitqueue_active(&vcpu->wq))
> -		wake_up_interruptible(&vcpu->wq);
> -
> -	me = get_cpu();
> -	if (cpu != me && (unsigned) cpu < nr_cpu_ids && cpu_online(cpu))
> -		if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests))
> -			smp_send_reschedule(cpu);
> -	put_cpu();
> -}
> -
>  int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq)
>  {
>  	return __apic_accept_irq(vcpu, irq->vector);
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index bf8af5d..b687444 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -438,4 +438,10 @@ struct kvm_vcpu_arch {
>  #define KVMPPC_VCPU_BUSY_IN_HOST	1
>  #define KVMPPC_VCPU_RUNNABLE		2
>  
> +#define __KVM_HAVE_ARCH_VCPU_GET_WQ 1
> +static inline wait_queue_head *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
> +{
> +	return vcpu->arch.wqp;
> +}
> +
>  #endif /* __POWERPC_KVM_HOST_H__ */
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 607fbdf..dd0c929 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -42,6 +42,11 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
>  	       !!(v->arch.pending_exceptions);
>  }
>  
> +int kvm_arch_vcpu_in_guest_mode(struct kvm_vcpu *vcpu)
> +{
> +	return kvm_vcpu_exiting_guest_mode(vcpu) = IN_GUEST_MODE;
> +}

As mentioned previously, i fail to see where powerpc kvm sets
vcpu->mode?

> +
>  int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
>  {
>  	int nr = kvmppc_get_gpr(vcpu, 11);
> @@ -311,10 +316,7 @@ static void kvmppc_decrementer_func(unsigned long data)
>  
>  	kvmppc_core_queue_dec(vcpu);
>  
> -	if (waitqueue_active(vcpu->arch.wqp)) {
> -		wake_up_interruptible(vcpu->arch.wqp);
> -		vcpu->stat.halt_wakeup++;
> -	}
> +	kvm_vcpu_kick(vcpu);
>  }
>  
>  /*
> @@ -363,7 +365,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  	mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
>  #endif
>  	kvmppc_core_vcpu_load(vcpu, cpu);
> -	vcpu->cpu = smp_processor_id();
>  }
>  
>  void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> @@ -572,12 +573,7 @@ int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
>  
>  	kvmppc_core_queue_external(vcpu, irq);
>  
> -	if (waitqueue_active(vcpu->arch.wqp)) {
> -		wake_up_interruptible(vcpu->arch.wqp);
> -		vcpu->stat.halt_wakeup++;
> -	} else if (vcpu->cpu != -1) {
> -		smp_send_reschedule(vcpu->cpu);
> -	}
> +	kvm_vcpu_kick(vcpu);
>  
>  	return 0;
>  }
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d1c44573..5e2217f 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -380,6 +380,14 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
>  	return 0;
>  }
>  
> +int kvm_arch_vcpu_in_guest_mode(struct kvm_vcpu *vcpu)
> +{
> +	/* kvm common code refers to this, but never calls it */
> +	BUG();
> +	return 0;
> +}
> +
> +
>  static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>  {
>  	kvm_s390_vcpu_initial_reset(vcpu);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c38efd7..a1761ff 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2252,7 +2252,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
>  		if (vcpu->cpu != cpu)
>  			kvm_migrate_timers(vcpu);
> -		vcpu->cpu = cpu;
>  	}

This is wrong, kvm_sched_in fails to see vcpu->cpu properly. Please
keep vcpu->cpu assignment in arch code.

>  	accumulate_steal_time(vcpu);
> @@ -6688,21 +6687,9 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
>  		 kvm_cpu_has_interrupt(vcpu));
>  }
>  
> -void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
> +int kvm_arch_vcpu_in_guest_mode(struct kvm_vcpu *vcpu)
>  {
> -	int me;
> -	int cpu = vcpu->cpu;
> -
> -	if (waitqueue_active(&vcpu->wq)) {
> -		wake_up_interruptible(&vcpu->wq);
> -		++vcpu->stat.halt_wakeup;
> -	}
> -
> -	me = get_cpu();
> -	if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
> -		if (kvm_vcpu_exiting_guest_mode(vcpu) = IN_GUEST_MODE)
> -			smp_send_reschedule(cpu);
> -	put_cpu();
> +	return kvm_vcpu_exiting_guest_mode(vcpu) = IN_GUEST_MODE;
>  }
>