[PATCH 5.15.y RESEND] KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

[PATCH 5.15.y RESEND] KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

[Justin Stitt]

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 -- it is
a false positive.

|  ../arch/arm64/kvm/sys_regs.c:2838:23: warning: variable 'clidr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
|   2838 |         get_clidr_el1(NULL, &clidr); /* Ugly... */
|        |                              ^~~~~

This patch isn't needed for anything past 6.1 as this code section was
reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache
configuration"). Since there is no upstream equivalent, this patch just
needs to be applied to 5.15.

Disable this warning for sys_regs.o with an iron fist as it doesn't make
sense to waste maintainer's time or potentially break builds by
backporting large changelists from 6.2+.

Cc: stable@vger.kernel.org
Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling")
Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e [1]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Resending this with Nathan's RB tag, an updated commit log and better
recipients from checkpatch.pl.

I'm also sending a similar patch resend for 6.1.
---
 arch/arm64/kvm/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 989bb5dad2c8..109cca425d3e 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -25,3 +25,6 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 vgic/vgic-its.o vgic/vgic-debug.o
 
 kvm-$(CONFIG_HW_PERF_EVENTS)  += pmu-emul.o
+
+# Work around a false positive Clang 22 -Wuninitialized-const-pointer warning
+CFLAGS_sys_regs.o := $(call cc-disable-warning, uninitialized-const-pointer)

---
base-commit: 8bb7eca972ad531c9b149c0a51ab43a417385813
change-id: 20250728-b4-stable-disable-uninit-ptr-warn-5-15-c0c9db3df206

Best regards,
--
Justin Stitt <justinstitt@google.com>

Re: [PATCH 5.15.y RESEND] KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

[Tiffany Yang]

Justin Stitt <justinstitt@google.com> writes:

> 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 -- it is
> a false positive.

> |  ../arch/arm64/kvm/sys_regs.c:2838:23: warning: variable 'clidr' is  
> uninitialized when passed as a const pointer argument here  
> [-Wuninitialized-const-pointer]
> |   2838 |         get_clidr_el1(NULL, &clidr); /* Ugly... */
> |        |                              ^~~~~

> This patch isn't needed for anything past 6.1 as this code section was
> reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache
> configuration"). Since there is no upstream equivalent, this patch just
> needs to be applied to 5.15.


This error has also been showing up in 5.10 since KernelCI started using
clang-21.

> Disable this warning for sys_regs.o with an iron fist as it doesn't make
> sense to waste maintainer's time or potentially break builds by
> backporting large changelists from 6.2+.

> Cc: stable@vger.kernel.org
> Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling")
> Link:  
> https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e  
> [1]
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Justin Stitt <justinstitt@google.com>
<snip>

Reviewed-by: Tiffany Yang <ynaffit@google.com>

-- 
Tiffany Y. Yang

Patch "KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning" has been added to the 5.10-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-arm64-sys_regs-disable-wuninitialized-const-pointer-warning.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From justinstitt@google.com  Thu Jan  8 16:52:32 2026
From: Justin Stitt <justinstitt@google.com>
Date: Thu, 04 Dec 2025 12:44:48 -0800
Subject: KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oliver.upton@linux.dev>,  Alexandru Elisei <alexandru.elisei@arm.com>, Joey Gouly <joey.gouly@arm.com>,  Suzuki K Poulose <suzuki.poulose@arm.com>, Catalin Marinas <catalin.marinas@arm.com>,  Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,  Nathan Chancellor <nathan@kernel.org>, Christopher Covington <cov@codeaurora.org>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,  linux-kernel@vger.kernel.org, llvm@lists.linux.dev, stable@vger.kernel.org,  Justin Stitt <justinstitt@google.com>
Message-ID: <20251204-b4-stable-disable-uninit-ptr-warn-5-15-v1-1-41212e2c6409@google.com>

From: Justin Stitt <justinstitt@google.com>

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 -- it is
a false positive.

|  ../arch/arm64/kvm/sys_regs.c:2838:23: warning: variable 'clidr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
|   2838 |         get_clidr_el1(NULL, &clidr); /* Ugly... */
|        |                              ^~~~~

This patch isn't needed for anything past 6.1 as this code section was
reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache
configuration"). Since there is no upstream equivalent, this patch just
needs to be applied to 5.15.

Disable this warning for sys_regs.o with an iron fist as it doesn't make
sense to waste maintainer's time or potentially break builds by
backporting large changelists from 6.2+.

Cc: stable@vger.kernel.org
Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling")
Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e [1]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm64/kvm/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 989bb5dad2c8..109cca425d3e 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -25,3 +25,6 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 vgic/vgic-its.o vgic/vgic-debug.o
 
 kvm-$(CONFIG_HW_PERF_EVENTS)  += pmu-emul.o
+
+# Work around a false positive Clang 22 -Wuninitialized-const-pointer warning
+CFLAGS_sys_regs.o := $(call cc-disable-warning, uninitialized-const-pointer)

---
base-commit: 8bb7eca972ad531c9b149c0a51ab43a417385813
change-id: 20250728-b4-stable-disable-uninit-ptr-warn-5-15-c0c9db3df206

Best regards,
--
Justin Stitt <justinstitt@google.com>



Patches currently in stable-queue which might be from justinstitt@google.com are

queue-5.10/kvm-arm64-sys_regs-disable-wuninitialized-const-pointer-warning.patch

Patch "KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning" has been added to the 5.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-arm64-sys_regs-disable-wuninitialized-const-pointer-warning.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From justinstitt@google.com  Thu Jan  8 16:52:32 2026
From: Justin Stitt <justinstitt@google.com>
Date: Thu, 04 Dec 2025 12:44:48 -0800
Subject: KVM: arm64: sys_regs: disable -Wuninitialized-const-pointer warning
To: Marc Zyngier <maz@kernel.org>, Oliver Upton <oliver.upton@linux.dev>,  Alexandru Elisei <alexandru.elisei@arm.com>, Joey Gouly <joey.gouly@arm.com>,  Suzuki K Poulose <suzuki.poulose@arm.com>, Catalin Marinas <catalin.marinas@arm.com>,  Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>,  Nathan Chancellor <nathan@kernel.org>, Christopher Covington <cov@codeaurora.org>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,  linux-kernel@vger.kernel.org, llvm@lists.linux.dev, stable@vger.kernel.org,  Justin Stitt <justinstitt@google.com>
Message-ID: <20251204-b4-stable-disable-uninit-ptr-warn-5-15-v1-1-41212e2c6409@google.com>

From: Justin Stitt <justinstitt@google.com>

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 -- it is
a false positive.

|  ../arch/arm64/kvm/sys_regs.c:2838:23: warning: variable 'clidr' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
|   2838 |         get_clidr_el1(NULL, &clidr); /* Ugly... */
|        |                              ^~~~~

This patch isn't needed for anything past 6.1 as this code section was
reworked in Commit 7af0c2534f4c ("KVM: arm64: Normalize cache
configuration"). Since there is no upstream equivalent, this patch just
needs to be applied to 5.15.

Disable this warning for sys_regs.o with an iron fist as it doesn't make
sense to waste maintainer's time or potentially break builds by
backporting large changelists from 6.2+.

Cc: stable@vger.kernel.org
Fixes: 7c8c5e6a9101e ("arm64: KVM: system register handling")
Link: https://github.com/llvm/llvm-project/commit/00dacf8c22f065cb52efb14cd091d441f19b319e [1]
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm64/kvm/Makefile |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -25,3 +25,6 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coales
 	 vgic/vgic-its.o vgic/vgic-debug.o
 
 kvm-$(CONFIG_HW_PERF_EVENTS)  += pmu-emul.o
+
+# Work around a false positive Clang 22 -Wuninitialized-const-pointer warning
+CFLAGS_sys_regs.o := $(call cc-disable-warning, uninitialized-const-pointer)


Patches currently in stable-queue which might be from justinstitt@google.com are

queue-5.15/kvm-arm64-sys_regs-disable-wuninitialized-const-pointer-warning.patch