From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH RFC v2 3/4] Break dependency between vcpu index in vcpus
 array and vcpu_id.
Date: Tue, 26 May 2009 11:34:01 +0300
Message-ID: <4A1BA979.4010808@redhat.com>
References: <1243266636-16914-1-git-send-email-gleb@redhat.com> <1243266636-16914-4-git-send-email-gleb@redhat.com>
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Cc: kvm@vger.kernel.org
To: Gleb Natapov <gleb@redhat.com>
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Gleb Natapov wrote:
> Archs are free to use vcpu_id as they see fit. For x86 it is used as
> vcpu's apic id.
>
>   

You need a KVM_CAP to inform userspace that the vcpu id has changed meaning.

>  inline int kvm_is_mmio_pfn(pfn_t pfn)
>  {
>  	if (pfn_valid(pfn)) {
> @@ -1713,15 +1708,12 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
>  /*
>   * Creates some virtual cpus.  Good luck creating more than one.
>   */
> -static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
> +static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  {
>  	int r;
>  	struct kvm_vcpu *vcpu;
>  
> -	if (!valid_vcpu(n))
> -		return -EINVAL;
> -
> -	vcpu = kvm_arch_vcpu_create(kvm, n);
> +	vcpu = kvm_arch_vcpu_create(kvm, id);
>  	if (IS_ERR(vcpu))
>  		return PTR_ERR(vcpu);
>  
> @@ -1732,25 +1724,36 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
>  		return r;
>  
>  	mutex_lock(&kvm->lock);
> -	if (kvm->vcpus[n]) {
> -		r = -EEXIST;
> +	if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
> +		r = -EINVAL;
>  		goto vcpu_destroy;
>  	}
> -	kvm->vcpus[n] = vcpu;
> -	if (n == 0)
> -		kvm->bsp_vcpu = vcpu;
> -	mutex_unlock(&kvm->lock);
> +
> +	for (r = 0; r < atomic_read(&kvm->online_vcpus); r++)
> +		if (kvm->vcpus[r]->vcpu_id == id) {
> +			r = -EEXIST;
> +			goto vcpu_destroy;
> +		}
> +
> +	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
>  
>  	/* Now it's all set up, let userspace reach it */
>  	kvm_get_kvm(kvm);
>  	r = create_vcpu_fd(vcpu);
> -	if (r < 0)
> -		goto unlink;
> +	if (r < 0) {
> +		kvm_put_kvm(kvm);
> +		goto vcpu_destroy;
> +	}
> +
> +	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
> +	smp_wmb();
> +	atomic_inc(&kvm->online_vcpus);
> +
> +	if (id == 0)
> +		kvm->bsp_vcpu = vcpu;
> +	mutex_unlock(&kvm->lock);
>  	return r;
>  
> -unlink:
> -	mutex_lock(&kvm->lock);
> -	kvm->vcpus[n] = NULL;
>  vcpu_destroy:
>  	mutex_unlock(&kvm->lock);
>  	kvm_arch_vcpu_destroy(vcpu);
>   

Don't the vcpu ioctls need to be updated?  They get the vcpu id as a 
parameter.


-- 
error compiling committee.c: too many arguments to function