Re: [kvmarm:fixes 18/18] arch/arm64/kvm/hyp/nvhe/mem_protect.c:1086:9: warning: variable 'ret' is uninitialized when used here

[Marc Zyngier <maz@kernel.org>]

On Mon, 10 Feb 2025 01:39:04 +0000,
kernel test robot <lkp@intel.com> wrote:
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git fixes
> head:   eabc7aaef7a553b64bf6e631ce04526af6c8d104
> commit: eabc7aaef7a553b64bf6e631ce04526af6c8d104 [18/18] KVM: arm64: Simplify np-guest hypercalls
> config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20250210/202502100911.8c9DbtKD-lkp@intel.com/config)
> compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250210/202502100911.8c9DbtKD-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@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202502100911.8c9DbtKD-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> arch/arm64/kvm/hyp/nvhe/mem_protect.c:1086:9: warning: variable 'ret' is uninitialized when used here [-Wuninitialized]
>     1086 |         return ret;
>          |                ^~~
>    arch/arm64/kvm/hyp/nvhe/mem_protect.c:1076:9: note: initialize the variable 'ret' to silence this warning
>     1076 |         int ret;
>          |                ^
>          |                 = 0
>    1 warning generated.

Nice catch. I wish the compiler would warn for these by default...

Quentin, are you happy with the following patch that I can stash on
top of the current set of fixes?

	M.

From 5da62486aeda7d7d11107db8ed4e6421e3a2a364 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@kernel.org>
Date: Mon, 10 Feb 2025 09:17:58 +0000
Subject: [PATCH] KVM: arm64: Fix __pkvm_host_mkyoung_guest() return value

Don't use an uninitialised stack variable, and just return 0
on the non-error path.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202502100911.8c9DbtKD-lkp@intel.com/
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 4c2f6a6a2efe1..19c3c631708ce 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1073,7 +1073,6 @@ int __pkvm_host_mkyoung_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu)
 {
 	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
 	u64 ipa = hyp_pfn_to_phys(gfn);
-	int ret;
 
 	if (pkvm_hyp_vm_is_protected(vm))
 		return -EPERM;
@@ -1083,5 +1082,5 @@ int __pkvm_host_mkyoung_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu)
 	kvm_pgtable_stage2_mkyoung(&vm->pgt, ipa, 0);
 	guest_unlock_component(vm);
 
-	return ret;
+	return 0;
 }
-- 
2.39.2


-- 
Without deviation from the norm, progress is not possible.