Re: [PATCH 1/1] css: SCHIB measurement block origin must be aligned

From: Thomas Huth <thuth@redhat.com>
To: Pierre Morel <pmorel@linux.ibm.com>, cohuck@redhat.com
Cc: david@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com,
	borntraeger@de.ibm.com, qemu-s390x@nongnu.org,
	imbrenda@linux.ibm.com, rth@twiddle.net
Subject: Re: [PATCH 1/1] css: SCHIB measurement block origin must be aligned
Date: Fri, 19 Feb 2021 07:23:20 +0100	[thread overview]
Message-ID: <23380d4e-39d0-0c49-e734-c0611ecc9a6e@redhat.com> (raw)
In-Reply-To: <1613670059-8406-2-git-send-email-pmorel@linux.ibm.com>

On 18/02/2021 18.40, Pierre Morel wrote:
> The Measurement Block Origin inside the SCHIB is used when
> Mesurement Block format 1 is in used and must be aligned
> on 128bits.

128 bits = 16 bytes ...

> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>   target/s390x/ioinst.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
> index a412926d27..1ee11522e1 100644
> --- a/target/s390x/ioinst.c
> +++ b/target/s390x/ioinst.c
> @@ -121,6 +121,12 @@ static int ioinst_schib_valid(SCHIB *schib)
>       if (be32_to_cpu(schib->pmcw.chars) & PMCW_CHARS_MASK_XMWME) {
>           return 0;
>       }
> +    /* for MB format 1 bits 26-31 of word 11 must be 0 */
> +    /* MBA uses words 10 and 11, it means align on 2**6 */
> +    if ((be16_to_cpu(schib->pmcw.chars) & PMCW_CHARS_MASK_MBFC) &&
> +        (be64_to_cpu(schib->mba) & 0x03fUL)) {

... but that checks for a 64 byte alignment...

And looking at the PoP, I also see some talk about 64 byte alignment there, 
so I guess you meant 64 byte insteas of 128 bit in the patch description?

  Thomas

> +        return 0;
> +    }
>       return 1;
>   }
>   
> 