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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>
Cc: qemu-devel <qemu-devel@nongnu.org>,
	qemu-s390x <qemu-s390x@nongnu.org>,
	Alexander Graf <agraf@suse.de>, Thomas Huth <thuth@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Janosch Frank <frankja@linux.vnet.ibm.com>,
	Halil Pasic <pasic@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] [PATCH 2/3] s390x/kvm: Handle bpb feature
Date: Wed, 17 Jan 2018 15:44:39 +0100	[thread overview]
Message-ID: <2017497a-8b3c-2e06-b89b-e2b30c71d0d8@de.ibm.com> (raw)
In-Reply-To: <bd0d62c3-9243-931b-a539-b32b3fc19cf9@redhat.com>



On 01/17/2018 03:30 PM, David Hildenbrand wrote:
> On 17.01.2018 15:18, Christian Borntraeger wrote:
>> We need to handle the bpb control on reset and migration. Normally
>> stfle.82 is transparent (and the normal guest part works without
>> hypervisor activity). To prevent any issues we require full
>> host kernel support for this feature.
> 
> Actually it is not transparent because we need hypervisor support to get
> VSIE running... or what am I missing? (or were you talking about bit 81?)

When you pass along the bit as a transparent bit (just enable it if the host
has it) it will work in nested guests. Its only that after reset or vsie you
have a short period of time where you work in a stale state.
Anyway we are aware that bit82 should have been a non-transparent bit, consider
it a quirk in the architecture. Thats why I handle this feature not in patch 3.

  reply	other threads:[~2018-01-17 14:44 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17 14:18 [Qemu-devel] [PATCH/RFC 0/3] s390x/kvm: implement new hardware/firmware features Christian Borntraeger
2018-01-17 14:18 ` [Qemu-devel] [PATCH 1/3] header sync Christian Borntraeger
2018-01-17 14:18 ` [Qemu-devel] [PATCH 2/3] s390x/kvm: Handle bpb feature Christian Borntraeger
2018-01-17 14:30   ` David Hildenbrand
2018-01-17 14:44     ` Christian Borntraeger [this message]
2018-01-17 14:37   ` Cornelia Huck
2018-01-17 14:50     ` David Hildenbrand
2018-01-17 14:59       ` Christian Borntraeger
2018-01-17 15:10         ` David Hildenbrand
2018-01-17 16:04           ` Christian Borntraeger
2018-01-17 16:06             ` David Hildenbrand
2018-01-17 16:28             ` Cornelia Huck
2018-01-17 16:07           ` Halil Pasic
2018-01-17 16:16             ` David Hildenbrand
2018-01-17 14:51     ` Christian Borntraeger
2018-01-17 14:18 ` [Qemu-devel] [PATCH 3/3] s390x/cpumodel: fix transparency for non-hyp STFL features Christian Borntraeger
2018-01-17 14:50   ` David Hildenbrand
2018-01-17 14:52   ` Cornelia Huck
2018-01-17 14:27 ` [Qemu-devel] [PATCH/RFC 0/3] s390x/kvm: implement new hardware/firmware features no-reply

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