Re: KVM build warnings

Takuya Yoshikawa
2011-05-30T10:14:26Z

On Mon, 30 May 2011 11:46:04 +0200
Borislav Petkov <bp@alien8.de> wrote:

> I get the following
>
> In file included from arch/x86/kvm/mmu.c:2856:
> arch/x86/kvm/paging_tmpl.h: In function ‘paging32_walk_addr_generic’:
> arch/x86/kvm/paging_tmpl.h:124: warning: ‘ptep_user’ may be used uninitialized in this function
> In file included from arch/x86/kvm/mmu.c:2852:
> arch/x86/kvm/paging_tmpl.h: In function ‘paging64_walk_addr_generic’:
> arch/x86/kvm/paging_tmpl.h:124: warning: ‘ptep_user’ may be used uninitialized in this function
>
> when building -rc1. It looks like it is caused by
> 6e2ca7d1802bf8ed9908435e34daa116662e7790 and sticking uninitialized_var() around
> the ptep_user declaration looks like the easiest solution. But the code should
> still be audited by someone who's familiar with it whether shutting up the
> compiler doesn't cause an actual bug.

Sorry, it is my commit.

I think the logic guarantees that ptep_user won't be used until it is
assigned some value.

It seems to be safe, IIUC.

Takuya