* [PATCH] KVM: s390: add explicit padding to struct kvm_s390_keyop
@ 2026-02-06 9:17 Arnd Bergmann
2026-02-06 10:33 ` Claudio Imbrenda
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2026-02-06 9:17 UTC (permalink / raw)
To: Paolo Bonzini, Claudio Imbrenda, Heiko Carstens
Cc: Arnd Bergmann, Oliver Upton, Sean Christopherson, Anup Patel,
Binbin Wu, Marc Zyngier, Jiaqi Yan, kvm, linux-kernel
From: Arnd Bergmann <arnd@arndb.de>
The newly added structure causes a warning about implied padding:
./usr/include/linux/kvm.h:1247:1: error: padding struct size to alignment boundary with 6 bytes [-Werror=padded]
The padding can lead to leaking kernel data and ABI incompatibilies
when used on x86. Neither of these is a problem in this specific
patch, but it's best to avoid it and use explicit padding fields
in general.
Fixes: 0ee4ddc1647b ("KVM: s390: Storage key manipulation IOCTL")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
I have a long series to add annotations to all existing structures,
but that will take a while. For now, I'm sending fixes when new
instances show up in linux-next.
---
include/uapi/linux/kvm.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a68b1741045c..1225fbd017e5 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1255,6 +1255,7 @@ struct kvm_s390_keyop {
__u64 guest_addr;
__u8 key;
__u8 operation;
+ __u8 pad[6];
};
/*
--
2.39.5
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH] KVM: s390: add explicit padding to struct kvm_s390_keyop
2026-02-06 9:17 [PATCH] KVM: s390: add explicit padding to struct kvm_s390_keyop Arnd Bergmann
@ 2026-02-06 10:33 ` Claudio Imbrenda
0 siblings, 0 replies; 2+ messages in thread
From: Claudio Imbrenda @ 2026-02-06 10:33 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Paolo Bonzini, Heiko Carstens, Arnd Bergmann, Oliver Upton,
Sean Christopherson, Anup Patel, Binbin Wu, Marc Zyngier,
Jiaqi Yan, kvm, linux-kernel
On Fri, 6 Feb 2026 10:17:30 +0100
Arnd Bergmann <arnd@kernel.org> wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> The newly added structure causes a warning about implied padding:
>
> ./usr/include/linux/kvm.h:1247:1: error: padding struct size to alignment boundary with 6 bytes [-Werror=padded]
>
> The padding can lead to leaking kernel data and ABI incompatibilies
> when used on x86. Neither of these is a problem in this specific
> patch, but it's best to avoid it and use explicit padding fields
> in general.
>
> Fixes: 0ee4ddc1647b ("KVM: s390: Storage key manipulation IOCTL")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
> I have a long series to add annotations to all existing structures,
> but that will take a while. For now, I'm sending fixes when new
> instances show up in linux-next.
> ---
> include/uapi/linux/kvm.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index a68b1741045c..1225fbd017e5 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1255,6 +1255,7 @@ struct kvm_s390_keyop {
> __u64 guest_addr;
> __u8 key;
> __u8 operation;
> + __u8 pad[6];
> };
>
> /*
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-02-06 9:17 [PATCH] KVM: s390: add explicit padding to struct kvm_s390_keyop Arnd Bergmann
2026-02-06 10:33 ` Claudio Imbrenda
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