From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 08/27] nVMX: Hold a vmcs02 for each vmcs12
Date: Sun, 17 Oct 2010 15:00:18 +0200
Message-ID: <4CBAF362.5010002@redhat.com>
References: <1287309814-nyh@il.ibm.com> <201010171007.o9HA7e8T029383@rice.haifa.ibm.com>
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Cc: kvm@vger.kernel.org, gleb@redhat.com
To: "Nadav Har'El" <nyh@il.ibm.com>
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  On 10/17/2010 12:07 PM, Nadav Har'El wrote:
> In this patch we add a list of L0 (hardware) VMCSs, which we'll use to hold a
> hardware VMCS for each active vmcs12 (i.e., for each L2 guest).
>
> We call each of these L0 VMCSs a "vmcs02", as it is the VMCS that L0 uses
> to run its nested guest L2.
>
> +
> +/*
> + * Allocate an L0 VMCS (vmcs02) for the current L1 VMCS (vmcs12), if one
> + * does not already exist. The allocation is done in L0 memory, so to avoid
> + * denial-of-service attack by guests, we limit the number of concurrently-
> + * allocated vmcss. A well-behaving L1 will VMCLEAR unused vmcs12s and not
> + * trigger this limit.
> + */
> +static const int NESTED_MAX_VMCS = 256;

#define, top of file

> +static int nested_create_current_vmcs(struct kvm_vcpu *vcpu)
> +{
> +	struct vmcs_list *new_l2_guest;
> +	struct vmcs *vmcs02;
> +
> +	if (nested_get_current_vmcs(vcpu))
> +		return 0; /* nothing to do - we already have a VMCS */
> +
> +	if (to_vmx(vcpu)->nested.vmcs02_num>= NESTED_MAX_VMCS)
> +		return -ENOMEM;

Why not just free_l1_state()?

You can have just nested_get_current_vmcs() which creates the vmcs if 
necessary and returns an old if cached.

> +
> +	new_l2_guest = (struct vmcs_list *)
> +		kmalloc(sizeof(struct vmcs_list), GFP_KERNEL);
> +	if (!new_l2_guest)
> +		return -ENOMEM;
> +
> +	vmcs02 = alloc_vmcs();
> +	if (!vmcs02) {
> +		kfree(new_l2_guest);
> +		return -ENOMEM;
> +	}
> +
> +	new_l2_guest->vmcs12_addr = to_vmx(vcpu)->nested.current_vmptr;
> +	new_l2_guest->vmcs02 = vmcs02;
> +	list_add(&(new_l2_guest->list),&(to_vmx(vcpu)->nested.vmcs02_list));
> +	to_vmx(vcpu)->nested.vmcs02_num++;
> +	return 0;
> +}
> +
>
> @@ -4409,6 +4503,8 @@ static void vmx_free_vcpu(struct kvm_vcp
>   		kunmap(to_vmx(vcpu)->nested.current_vmcs12_page);
>   		nested_release_page(to_vmx(vcpu)->nested.current_vmcs12_page);
>   	}
> +	if (vmx->nested.vmxon)
> +		free_l1_state(vcpu);

Can be called unconditionally.

>   	vmx_free_vmcs(vcpu);
>   	kfree(vmx->guest_msrs);
>   	kvm_vcpu_uninit(vcpu);


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