Re: [Qemu-devel] [PATCH v1 2/2] s390x/tcg: Store only the necessary amount of doublewords for STFLE

From: David Hildenbrand <david@redhat.com>
To: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Cc: Stefan Liebler <stli@linux.ibm.com>,
	Thomas Huth <thuth@redhat.com>,
	Andreas Krebbel <Andreas.Krebbel@de.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	qemu-s390x@nongnu.org, Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH v1 2/2] s390x/tcg: Store only the necessary amount of doublewords for STFLE
Date: Fri, 31 May 2019 17:08:17 +0200	[thread overview]
Message-ID: <21f88571-de38-5ea4-3904-192c3e96738e@redhat.com> (raw)
In-Reply-To: <399b78dc-8a1f-65a2-2e00-15460dbbe4bb@linaro.org>

On 31.05.19 17:05, Richard Henderson wrote:
> On 5/31/19 9:56 AM, David Hildenbrand wrote:
>> @@ -678,7 +678,7 @@ uint32_t HELPER(stfle)(CPUS390XState *env, uint64_t addr)
>>  
>>      prepare_stfl();
>>      max_bytes = ROUND_UP(used_stfl_bytes, 8);
>> -    for (i = 0; i < count_bytes; ++i) {
>> +    for (i = 0; i < MIN(count_bytes, max_bytes); ++i) {
> 
> Before the loop, please put something like
> 
>     /*
>      * The PoP says that doublewords beyond the highest-numbered
>      * facility bit may or may not be stored.  However, existing
>      * hardware appears to not store the words, and existing
>      * software appears to depend on that.
>      */
> 
> with that,
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> 

Makes sense, thanks for the ultra-fast review!

(have a great weekend!)

-- 

Thanks,

David / dhildenb