From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH 1/2] KVM: s390: sthyi: fix sthyi inline assembly
Date: Mon, 21 Aug 2017 15:07:59 +0200
Message-ID: <20170821150759.6e243678.cohuck@redhat.com>
References: <1503318465-19013-1-git-send-email-borntraeger@de.ibm.com>
        <1503318465-19013-2-git-send-email-borntraeger@de.ibm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Return-path: <kvm-owner@vger.kernel.org>
In-Reply-To: <1503318465-19013-2-git-send-email-borntraeger@de.ibm.com>
Sender: kvm-owner@vger.kernel.org
List-Archive: <https://lore.kernel.org/kvm/>
List-Post: <mailto:kvm@vger.kernel.org>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: KVM <kvm@vger.kernel.org>, Cornelia Huck <cohuck@redhat.com>, linux-s390 <linux-s390@vger.kernel.org>, Heiko Carstens <heiko.carstens@de.ibm.com>
List-ID: <linux-s390.vger.kernel.org>

On Mon, 21 Aug 2017 14:27:44 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: Heiko Carstens <heiko.carstens@de.ibm.com>
> 
> The sthyi inline assembly misses register r3 within the clobber
> list. The sthyi instruction will always write a return code to
> register "R2+1", which in this case would be r3. Due to that we may
> have register corruption and see host crashes or data corruption
> depending on how gcc decided to allocate and use registers during
> compile time.
> 
> Fixes: 95ca2cb57985 ("KVM: s390: Add sthyi emulation")
> Cc: <stable@vger.kernel.org> # 4.8+
> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/sthyi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/sthyi.c b/arch/s390/kvm/sthyi.c
> index 926b524..2773a2f 100644
> --- a/arch/s390/kvm/sthyi.c
> +++ b/arch/s390/kvm/sthyi.c
> @@ -394,7 +394,7 @@ static int sthyi(u64 vaddr)
>  		"srl     %[cc],28\n"
>  		: [cc] "=d" (cc)
>  		: [code] "d" (code), [addr] "a" (addr)
> -		: "memory", "cc");
> +		: "3", "memory", "cc");
>  	return cc;
>  }
>  

Reviewed-by: Cornelia Huck <cohuck@redhat.com>