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From: David Hildenbrand <david@redhat.com>
To: Richard Henderson <rth@twiddle.net>,
	Thomas Huth <thuth@redhat.com>, Michal Marek <mmarek@suse.com>,
	Alexander Graf <agraf@suse.de>
Cc: Eric Bischoff <ebischoff@suse.com>,
	Miroslav Benes <mbenes@suse.cz>,
	qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v4] target-s390x: Implement stfl and stfle
Date: Thu, 2 Mar 2017 14:09:48 +0100	[thread overview]
Message-ID: <fea39dac-e9da-c466-a7a2-d55a726272b0@redhat.com> (raw)
In-Reply-To: <ea3392d8-cd07-64e0-134a-4f111fe853db@twiddle.net>

>>> Of course, in practice we could reduce this to just one cpu_stl_data for
>>> STFL and one or two cpu_stq_data for STFLE.
>>
>> I think STFLE can store more than two 64-bit words, can't it?
> 
> Technically, yes.  But there are less than 128 bits defined.  Certainly much 
> less than the 4k bits that Michal prepares for.
> 

The architectural limit is 2k bytes (yes I said bytes).

Check out "struct kvm_s390_vm_cpu_machine - fac_list" /
KVM_S390_VM_CPU_MACHINE in
arch/s390/include/uapi/asm/kvm.h. Here we prepared for that.

Also note preparations for new stfl bits for future HW:

cd1836f583d7 (KVM: s390: instruction-execution-protection support)
-> bit 130
a679c547d19d (KVM: s390: gaccess: add ESOP2 handling)
-> bit 131

However, for now 128 bit should be more then enough, as TCG still misses
loads of features. CPU model still isn't properly wired up for TCG yet.

-- 
Thanks,

David

  parent reply	other threads:[~2017-03-02 13:09 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-24 13:44 [Qemu-devel] [PATCH] target-s390x: Implement stfl and stfle Michal Marek
2017-02-24 14:51 ` no-reply
2017-02-24 15:22   ` Michal Marek
2017-02-24 16:28     ` David Hildenbrand
2017-02-25  0:05 ` Richard Henderson
2017-02-25 20:39   ` Michal Marek
2017-02-25 23:30     ` Michal Marek
2017-02-25 23:16   ` [Qemu-devel] [PATCH v2] " Michal Marek
2017-02-25 23:38     ` [Qemu-devel] [PATCH v3] " Michal Marek
2017-02-26 11:22       ` Thomas Huth
2017-02-26 18:57         ` Michal Marek
2017-02-27  7:30           ` Thomas Huth
2017-02-27 10:18         ` [Qemu-devel] [PATCH v4] " Michal Marek
2017-02-28 22:11           ` Richard Henderson
2017-03-01  8:00             ` Thomas Huth
2017-03-01 19:30               ` Richard Henderson
2017-03-01 20:20                 ` Thomas Huth
2017-03-02 13:09                 ` David Hildenbrand [this message]
2017-03-02 10:53             ` Michal Marek
2017-03-02 13:12               ` David Hildenbrand

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