linux-kernel - Re: [PATCH 04/61] KVM: x86: Clean up error handling in kvm_dev_ioctl_get

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Message-ID: <87mu9vg3b2.fsf@vitty.brq.redhat.com>
Date:   Thu, 06 Feb 2020 16:09:53 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 04/61] KVM: x86: Clean up error handling in kvm_dev_ioctl_get_cpuid()

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Clean up the error handling in kvm_dev_ioctl_get_cpuid(), which has
> gotten a bit crusty as the function has evolved over the years.
>
> Opportunistically hoist the static @funcs declaration to the top of the
> function to make it more obvious that it's a "static const".
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/cpuid.c | 19 +++++++------------
>  1 file changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index de52cbb46171..11d5f311ef10 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -889,45 +889,40 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
>  			    struct kvm_cpuid_entry2 __user *entries,
>  			    unsigned int type)
>  {
> -	struct kvm_cpuid_entry2 *cpuid_entries;
> -	int nent = 0, r = -E2BIG, i;
> -
>  	static const u32 funcs[] = {
>  		0, 0x80000000, CENTAUR_CPUID_SIGNATURE, KVM_CPUID_SIGNATURE,
>  	};
>  
> +	struct kvm_cpuid_entry2 *cpuid_entries;
> +	int nent = 0, r, i;
> +
>  	if (cpuid->nent < 1)
> -		goto out;
> +		return -E2BIG;
>  	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
>  		cpuid->nent = KVM_MAX_CPUID_ENTRIES;
>  
>  	if (sanity_check_entries(entries, cpuid->nent, type))
>  		return -EINVAL;
>  
> -	r = -ENOMEM;
>  	cpuid_entries = vzalloc(array_size(sizeof(struct kvm_cpuid_entry2),
>  					   cpuid->nent));
>  	if (!cpuid_entries)
> -		goto out;
> +		return -ENOMEM;
>  
> -	r = 0;
>  	for (i = 0; i < ARRAY_SIZE(funcs); i++) {
>  		r = get_cpuid_func(cpuid_entries, funcs[i], &nent, cpuid->nent,
>  				   type);
>  		if (r)
>  			goto out_free;
>  	}
> +	cpuid->nent = nent;
>  
> -	r = -EFAULT;
>  	if (copy_to_user(entries, cpuid_entries,
>  			 nent * sizeof(struct kvm_cpuid_entry2)))
> -		goto out_free;
> -	cpuid->nent = nent;
> -	r = 0;
> +		r = -EFAULT;
>  
>  out_free:
>  	vfree(cpuid_entries);
> -out:
>  	return r;
>  }

Please [partially] disregard my comment on PATCH 02

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly