linux-kernel - Re: [PATCH v1 1/1] KVM: s390: Increase permitted SE header size to 1 MiB

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Message-ID: <20260209181610.550b8ff0@p-imbrenda>
Date: Mon, 9 Feb 2026 18:16:10 +0100
From: Claudio Imbrenda <imbrenda@...ux.ibm.com>
To: Steffen Eiden <seiden@...ux.ibm.com>
Cc: linux-s390@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Christian Borntraeger
 <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Andreas
 Grapentin <gra@...ux.ibm.com>,
        Hendrik Brueckner <brueckner@...ux.ibm.com>
Subject: Re: [PATCH v1 1/1] KVM: s390: Increase permitted SE header size to
 1 MiB

On Mon,  9 Feb 2026 16:29:25 +0100
Steffen Eiden <seiden@...ux.ibm.com> wrote:

> Relax the maximum allowed Secure Execution (SE) header size from
> 8 KiB to 1 MiB. This allows individual secure guest images to run on a
> wider range of physical machines.
> 
> Signed-off-by: Steffen Eiden <seiden@...ux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>

> ---
>  arch/s390/kvm/kvm-s390.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 56a50524b3ee..3428a8d427b2 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2744,9 +2744,9 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  		if (copy_from_user(&parms, argp, sizeof(parms)))
>  			break;
>  
> -		/* Currently restricted to 8KB */
> +		/* Currently restricted to 1MiB */
>  		r = -EINVAL;
> -		if (parms.length > PAGE_SIZE * 2)
> +		if (parms.length > SZ_1M)
>  			break;
>  
>  		r = -ENOMEM;