[RFC,v3,3/9] KVM: remember position in kvm->vcpus array

Message ID 20170821203530.9266-4-rkrcmar@redhat.com
State Changes Requested
Headers show

Commit Message

Radim Krčmář Aug. 21, 2017, 8:35 p.m.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 include/linux/kvm_host.h | 11 +++--------
 virt/kvm/kvm_main.c      |  5 ++++-
 2 files changed, 7 insertions(+), 9 deletions(-)

Comments

David Hildenbrand Aug. 22, 2017, 11:44 a.m. | #1
On 21.08.2017 22:35, Radim Krčmář wrote:
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  include/linux/kvm_host.h | 11 +++--------
>  virt/kvm/kvm_main.c      |  5 ++++-
>  2 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 6882538eda32..a8ff956616d2 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -220,7 +220,8 @@ struct kvm_vcpu {
>  	struct preempt_notifier preempt_notifier;
>  #endif
>  	int cpu;
> -	int vcpu_id;
> +	int vcpu_id; /* id given by userspace at creation */
> +	int vcpus_idx; /* index in kvm->vcpus array */
>  	int srcu_idx;
>  	int mode;
>  	unsigned long requests;
> @@ -516,13 +517,7 @@ static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
>  
>  static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu)
>  {
> -	struct kvm_vcpu *tmp;
> -	int idx;
> -
> -	kvm_for_each_vcpu(idx, tmp, vcpu->kvm)
> -		if (tmp == vcpu)
> -			return idx;
> -	BUG();
> +	return vcpu->vcpus_idx;
>  }
>  
>  #define kvm_for_each_memslot(memslot, slots)	\
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e17c40d986f3..caf8323f7df7 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2498,7 +2498,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  		goto unlock_vcpu_destroy;
>  	}
>  
> -	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
> +	vcpu->vcpus_idx = atomic_read(&kvm->online_vcpus);
> +
> +	BUG_ON(kvm->vcpus[vcpu->vcpus_idx]);
> +
>  
>  	/* Now it's all set up, let userspace reach it */
>  	kvm_get_kvm(kvm);
> 

Reviewed-by: David Hildenbrand <david@redhat.com>
Cornelia Huck Aug. 29, 2017, 11:30 a.m. | #2
On Mon, 21 Aug 2017 22:35:24 +0200
Radim Krčmář <rkrcmar@redhat.com> wrote:

> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  include/linux/kvm_host.h | 11 +++--------
>  virt/kvm/kvm_main.c      |  5 ++++-
>  2 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 6882538eda32..a8ff956616d2 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -220,7 +220,8 @@ struct kvm_vcpu {
>  	struct preempt_notifier preempt_notifier;
>  #endif
>  	int cpu;
> -	int vcpu_id;
> +	int vcpu_id; /* id given by userspace at creation */
> +	int vcpus_idx; /* index in kvm->vcpus array */

I predict confusion in the future over which is which... maybe
s/vcpus_idx/vcpus_array_pos/ or something like that?

>  	int srcu_idx;
>  	int mode;
>  	unsigned long requests;
> @@ -516,13 +517,7 @@ static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
>  
>  static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu)
>  {
> -	struct kvm_vcpu *tmp;
> -	int idx;
> -
> -	kvm_for_each_vcpu(idx, tmp, vcpu->kvm)
> -		if (tmp == vcpu)
> -			return idx;
> -	BUG();
> +	return vcpu->vcpus_idx;
>  }
>  
>  #define kvm_for_each_memslot(memslot, slots)	\
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e17c40d986f3..caf8323f7df7 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2498,7 +2498,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  		goto unlock_vcpu_destroy;
>  	}
>  
> -	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
> +	vcpu->vcpus_idx = atomic_read(&kvm->online_vcpus);
> +
> +	BUG_ON(kvm->vcpus[vcpu->vcpus_idx]);
> +
>  
>  	/* Now it's all set up, let userspace reach it */
>  	kvm_get_kvm(kvm);

I like the concept.
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Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6882538eda32..a8ff956616d2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -220,7 +220,8 @@  struct kvm_vcpu {
 	struct preempt_notifier preempt_notifier;
 #endif
 	int cpu;
-	int vcpu_id;
+	int vcpu_id; /* id given by userspace at creation */
+	int vcpus_idx; /* index in kvm->vcpus array */
 	int srcu_idx;
 	int mode;
 	unsigned long requests;
@@ -516,13 +517,7 @@  static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
 
 static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu *tmp;
-	int idx;
-
-	kvm_for_each_vcpu(idx, tmp, vcpu->kvm)
-		if (tmp == vcpu)
-			return idx;
-	BUG();
+	return vcpu->vcpus_idx;
 }
 
 #define kvm_for_each_memslot(memslot, slots)	\
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e17c40d986f3..caf8323f7df7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2498,7 +2498,10 @@  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 		goto unlock_vcpu_destroy;
 	}
 
-	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
+	vcpu->vcpus_idx = atomic_read(&kvm->online_vcpus);
+
+	BUG_ON(kvm->vcpus[vcpu->vcpus_idx]);
+
 
 	/* Now it's all set up, let userspace reach it */
 	kvm_get_kvm(kvm);