linux-kernel - Re: [PATCH 6.1.y] KVM: arm64: silence -Wuninitialized-const-pointer warning

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Message-ID: <xcwmzitmc5igc3eplgr2uwviitdfmtdknth4a5zpaldamw7png@o22wb4ze3czd>
Date: Thu, 24 Jul 2025 18:19:53 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>, 
	Alexandru Elisei <alexandru.elisei@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Oliver Upton <oliver.upton@...ux.dev>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Nathan Chancellor <nathan@...nel.org>, Tom Rix <trix@...hat.com>, 
	Christopher Covington <cov@...eaurora.org>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
	stable@...r.kernel.org
Subject: Re: [PATCH 6.1.y] KVM: arm64: silence -Wuninitialized-const-pointer
 warning

On Thu, Jul 24, 2025 at 06:15:28PM -0700, Justin Stitt wrote:
> A new warning in Clang 22 [1] complains that @clidr passed to
> get_clidr_el1() is an uninitialized const pointer. get_clidr_el1()
> doesn't really care since it casts away the const-ness anyways.
> 
> Silence the warning by initializing the struct.

For posterity's sake, here's the warning message which I meant to
include in the patch:

../arch/arm64/kvm/sys_regs.c:2978:23: warning: variable 'clidr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
 2978 |         get_clidr_el1(NULL, &clidr); /* Ugly... */

> 
> This patch won't apply to anything past v6.1 as this code section was
> reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache configuration").
> 
> Cc: stable@...r.kernel.org
> Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling")
> Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e [1]
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>
> ---
>  arch/arm64/kvm/sys_regs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index f4a7c5abcbca..d7ebd7387221 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -2948,7 +2948,7 @@ int kvm_sys_reg_table_init(void)
>  {
>  	bool valid = true;
>  	unsigned int i;
> -	struct sys_reg_desc clidr;
> +	struct sys_reg_desc clidr = {0};
>  
>  	/* Make sure tables are unique and in order. */
>  	valid &= check_sysreg_table(sys_reg_descs, ARRAY_SIZE(sys_reg_descs), false);
> 
> ---
> base-commit: 830b3c68c1fb1e9176028d02ef86f3cf76aa2476
> change-id: 20250724-b4-clidr-unint-const-ptr-7edb960bc3bd
> 
> Best regards,
> --
> Justin Stitt <justinstitt@...gle.com>
>