linux-kernel - Re: [PATCH] KVM: Fix a warning in __kvm_gfn_to_hva_cache

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Message-ID: <871e801d-10dc-f1d5-a4a5-efc6824ebd21@redhat.com>
Date:   Tue, 5 May 2020 09:20:27 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     Peter Xu <peterx@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH] KVM: Fix a warning in __kvm_gfn_to_hva_cache_init()

On 5/5/20 5:05 AM, Peter Xu wrote:
> GCC 10.0.1 gives me this warning when building KVM:
> 
>    warning: ‘nr_pages_avail’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    2442 |  for ( ; start_gfn <= end_gfn; start_gfn += nr_pages_avail) {
> 
> It should not happen, but silent it.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>   virt/kvm/kvm_main.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Gavin Shan <gshan@...hat.com>

> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 74bdb7bf3295..2da293885a67 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2425,7 +2425,7 @@ static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
>   	gfn_t start_gfn = gpa >> PAGE_SHIFT;
>   	gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
>   	gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
> -	gfn_t nr_pages_avail;
> +	gfn_t nr_pages_avail = 0;
>   
>   	/* Update ghc->generation before performing any error checks. */
>   	ghc->generation = slots->generation;
>