From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Barret Rhoden <brho@google.com>
Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: squelch uninitialized variable warning
Date: Thu, 9 Jan 2020 14:04:01 -0800 [thread overview]
Message-ID: <20200109220401.GA2682@linux.intel.com> (raw)
In-Reply-To: <20200109195855.17353-1-brho@google.com>
On Thu, Jan 09, 2020 at 02:58:55PM -0500, Barret Rhoden wrote:
> If gfn_to_hva_many() fails, __kvm_gfn_to_hva_cache_init() will return an
> error. Before it does, it might use nr_pages_avail, which my compiler
> complained about:
>
> virt/kvm/kvm_main.c:2193:13: warning: 'nr_pages_avail' may be
> used uninitialized in this function [-Wmaybe-uninitialized]
>
> start_gfn += nr_pages_avail;
Ugh, this whole flow is funky. The change is correct, and is certainly the
minimal change if we want to backport this to stable, but IMO it's putting
lipstick on a pig. I'd rather fix the underlying issues and make the code
more readable in the process. I'll send a patch.
If we want to take this as a minimal fix,
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Barret Rhoden <brho@google.com>
> ---
> virt/kvm/kvm_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index d9aced677ddd..f8249b153d33 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2172,7 +2172,7 @@ 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;
> int r = start_gfn <= end_gfn ? 0 : -EINVAL;
>
> ghc->gpa = gpa;
> --
> 2.25.0.rc1.283.g88dfdc4193-goog
>
next prev parent reply other threads:[~2020-01-09 22:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 19:58 [PATCH] KVM: squelch uninitialized variable warning Barret Rhoden
2020-01-09 22:04 ` Sean Christopherson [this message]
2020-01-18 20:19 ` Paolo Bonzini
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