From: Cornelia Huck <cohuck@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: david@redhat.com, Ulrich.Weigand@de.ibm.com, aarcange@redhat.com,
akpm@linux-foundation.org, frankja@linux.vnet.ibm.com,
gor@linux.ibm.com, imbrenda@linux.ibm.com, kvm@vger.kernel.org,
linux-mm@kvack.org, linux-s390@vger.kernel.org,
mimu@linux.ibm.com, thuth@redhat.com
Subject: Re: [PATCH v2 RFC] KVM: s390/interrupt: do not pin adapter interrupt pages
Date: Wed, 12 Feb 2020 14:07:29 +0100 [thread overview]
Message-ID: <20200212140729.21209127.cohuck@redhat.com> (raw)
In-Reply-To: <ba5862cd-c0ff-c0f1-bf00-8220fa407d52@de.ibm.com>
On Wed, 12 Feb 2020 13:44:53 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> On 12.02.20 13:39, Cornelia Huck wrote:
> [...]
>
> >> + */
> >> + return 0;
> >
> > Given that this function now always returns 0, we basically get a
> > completely useless roundtrip into the kernel when userspace is trying
> > to setup the mappings.
> >
> > Can we define a new IO_ADAPTER_MAPPING_NOT_NEEDED or so capability that
> > userspace can check?
>
> Nack. This is one system call per initial indicator ccw. This is so seldom
> and cheap that I do not see a point in optimizing this.
NB that zpci also calls this. Probably a rare event there as well.
>
>
> > This change in behaviour probably wants a change in the documentation
> > as well.
>
> Yep.
next prev parent reply other threads:[~2020-02-12 13:07 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 11:39 [PATCH 00/35] KVM: s390: Add support for protected VMs Christian Borntraeger
2020-02-07 11:39 ` [PATCH 01/35] mm:gup/writeback: add callbacks for inaccessible pages Christian Borntraeger
2020-02-10 17:27 ` Christian Borntraeger
2020-02-11 11:26 ` Will Deacon
2020-02-11 11:43 ` Christian Borntraeger
2020-02-13 14:48 ` Christian Borntraeger
2020-02-18 16:02 ` Will Deacon
2020-02-13 19:56 ` Sean Christopherson
2020-02-13 20:13 ` Christian Borntraeger
2020-02-13 20:46 ` Sean Christopherson
2020-02-17 20:55 ` Tom Lendacky
2020-02-17 21:14 ` Christian Borntraeger
2020-02-10 18:17 ` David Hildenbrand
2020-02-10 18:28 ` Christian Borntraeger
2020-02-10 18:43 ` David Hildenbrand
2020-02-10 18:51 ` Christian Borntraeger
2020-02-18 3:36 ` Tian, Kevin
2020-02-18 6:44 ` Christian Borntraeger
2020-02-07 11:39 ` [PATCH 02/35] KVM: s390/interrupt: do not pin adapter interrupt pages Christian Borntraeger
2020-02-10 12:26 ` David Hildenbrand
2020-02-10 18:38 ` Christian Borntraeger
2020-02-10 19:33 ` David Hildenbrand
2020-02-11 9:23 ` [PATCH v2 RFC] " Christian Borntraeger
2020-02-12 11:52 ` Christian Borntraeger
2020-02-12 12:16 ` David Hildenbrand
2020-02-12 12:22 ` Christian Borntraeger
2020-02-12 12:47 ` David Hildenbrand
2020-02-12 12:39 ` Cornelia Huck
2020-02-12 12:44 ` Christian Borntraeger
2020-02-12 13:07 ` Cornelia Huck [this message]
2020-02-10 18:56 ` [PATCH 02/35] KVM: s390/interrupt: do not pin adapter interrupt Ulrich Weigand
2020-02-10 12:40 ` [PATCH 02/35] KVM: s390/interrupt: do not pin adapter interrupt pages David Hildenbrand
2020-02-07 11:39 ` [PATCH 05/35] s390/mm: provide memory management functions for protected KVM guests Christian Borntraeger
2020-02-12 13:42 ` Cornelia Huck
2020-02-13 7:43 ` Christian Borntraeger
2020-02-13 8:44 ` Cornelia Huck
2020-02-14 17:59 ` David Hildenbrand
2020-02-14 21:17 ` Christian Borntraeger
2020-02-07 11:39 ` [PATCH 06/35] s390/mm: add (non)secure page access exceptions handlers Christian Borntraeger
2020-02-14 18:05 ` David Hildenbrand
2020-02-14 19:59 ` Christian Borntraeger
2020-02-07 11:39 ` [PATCH 10/35] KVM: s390: protvirt: Secure memory is not mergeable Christian Borntraeger
2020-02-07 11:39 ` [PATCH 11/35] KVM: s390/mm: Make pages accessible before destroying the guest Christian Borntraeger
2020-02-14 18:40 ` David Hildenbrand
2020-02-07 11:39 ` [PATCH 21/35] KVM: s390/mm: handle guest unpin events Christian Borntraeger
2020-02-10 14:58 ` Thomas Huth
2020-02-11 13:21 ` Cornelia Huck
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