linux-kernel - Re: [PATCH v8 04/11] KVM: x86/mmu: Relax locking for kvm_test_age_gfn and kvm_age

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Message-ID: <CADrL8HU3KzDxrLsxD1+578zG6E__AjK3TMCfs-nQAnqFTZM2vQ@mail.gmail.com>
Date: Thu, 7 Nov 2024 22:00:13 -0500
From: James Houghton <jthoughton@...gle.com>
To: kernel test robot <lkp@...el.com>
Cc: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	oe-kbuild-all@...ts.linux.dev, David Matlack <dmatlack@...gle.com>, 
	David Rientjes <rientjes@...gle.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Wei Xu <weixugc@...gle.com>, Yu Zhao <yuzhao@...gle.com>, 
	Axel Rasmussen <axelrasmussen@...gle.com>, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 04/11] KVM: x86/mmu: Relax locking for kvm_test_age_gfn
 and kvm_age_gfn

On Wed, Nov 6, 2024 at 3:22 AM kernel test robot <lkp@...el.com> wrote:
>
> Hi James,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on a27e0515592ec9ca28e0d027f42568c47b314784]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/James-Houghton/KVM-Remove-kvm_handle_hva_range-helper-functions/20241106-025133
> base:   a27e0515592ec9ca28e0d027f42568c47b314784
> patch link:    https://lore.kernel.org/r/20241105184333.2305744-5-jthoughton%40google.com
> patch subject: [PATCH v8 04/11] KVM: x86/mmu: Relax locking for kvm_test_age_gfn and kvm_age_gfn
> config: x86_64-rhel-8.3 (https://download.01.org/0day-ci/archive/20241106/202411061526.RAuCXKJh-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241106/202411061526.RAuCXKJh-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202411061526.RAuCXKJh-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
>    arch/x86/kvm/mmu/tdp_mmu.c: In function 'kvm_tdp_mmu_age_spte':
> >> arch/x86/kvm/mmu/tdp_mmu.c:1189:23: warning: ignoring return value of '__tdp_mmu_set_spte_atomic' declared with attribute 'warn_unused_result' [-Wunused-result]
>     1189 |                 (void)__tdp_mmu_set_spte_atomic(iter, new_spte);
>          |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>

Well, I saw this compiler warning in my latest rebase and thought the
`(void)` would fix it. I guess the next best way to fix it would be to
assign to an `int __maybe_unused`. I'll do for a v9, or Sean if you're
going to take the series (maybe? :)), go ahead and apply whatever fix
you like.