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From: David Hildenbrand <david@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: KVM <kvm@vger.kernel.org>, Cornelia Huck <cohuck@redhat.com>,
	Thomas Huth <thuth@redhat.com>,
	Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Michael Mueller <mimu@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm@kvack.org, Will Deacon <will@kernel.org>
Subject: Re: [PATCH v3 01/37] mm:gup/writeback: add callbacks for inaccessible pages
Date: Thu, 20 Feb 2020 13:15:05 +0100	[thread overview]
Message-ID: <c47b3511-2447-e463-abb8-9bd3f35932c8@redhat.com> (raw)
In-Reply-To: <20200220104020.5343-2-borntraeger@de.ibm.com>

On 20.02.20 11:39, Christian Borntraeger wrote:
> From: Claudio Imbrenda <imbrenda@linux.ibm.com>
> 
> With the introduction of protected KVM guests on s390 there is now a
> concept of inaccessible pages. These pages need to be made accessible
> before the host can access them.
> 
> While cpu accesses will trigger a fault that can be resolved, I/O
> accesses will just fail.  We need to add a callback into architecture
> code for places that will do I/O, namely when writeback is started or
> when a page reference is taken.
> 
> This is not only to enable paging, file backing etc, it is also
> necessary to protect the host against a malicious user space. For
> example a bad QEMU could simply start direct I/O on such protected
> memory.  We do not want userspace to be able to trigger I/O errors and
> thus we the logic is "whenever somebody accesses that page (gup) or
> doing I/O, make sure that this page can be accessed. When the guest
> tries to access that page we will wait in the page fault handler for
> writeback to have finished and for the page_ref to be the expected
> value.


Subject: "mm: gup..."

And I'd probably add that on s390x, it's unlikely to ever return !0.
(why the WARN_ON is okay and has to be tackled once relevant)

> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Acked-by: Will Deacon <will@kernel.org>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

  reply	other threads:[~2020-02-20 12:15 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20 10:39 [PATCH v3 00/37] KVM: s390: Add support for protected VMs Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 01/37] mm:gup/writeback: add callbacks for inaccessible pages Christian Borntraeger
2020-02-20 12:15   ` David Hildenbrand [this message]
2020-02-20 10:39 ` [PATCH v3 02/37] KVM: s390/interrupt: do not pin adapter interrupt pages Christian Borntraeger
2020-02-21  8:09   ` [PATCH v3.1 " Christian Borntraeger
2020-02-21  9:50     ` David Hildenbrand
2020-02-21 10:41     ` Cornelia Huck
2020-02-21 11:05       ` Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 03/37] s390/protvirt: introduce host side setup Christian Borntraeger
2020-02-21 12:39   ` Cornelia Huck
2020-02-20 10:39 ` [PATCH v3 04/37] s390/protvirt: add ultravisor initialization Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 05/37] s390/mm: provide memory management functions for protected KVM guests Christian Borntraeger
2020-02-20 12:25   ` David Hildenbrand
2020-02-20 10:39 ` [PATCH v3 06/37] s390/mm: add (non)secure page access exceptions handlers Christian Borntraeger
2020-02-21 10:38   ` David Hildenbrand
2020-02-20 10:39 ` [PATCH v3 07/37] KVM: s390: protvirt: Add UV debug trace Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 08/37] KVM: s390: add new variants of UV CALL Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 09/37] KVM: s390: protvirt: Add initial vm and cpu lifecycle handling Christian Borntraeger
2020-02-20 13:02   ` David Hildenbrand
2020-02-20 19:44     ` Christian Borntraeger
2020-02-21  8:07       ` [PATCH v3.1 " Christian Borntraeger
2020-02-21 11:45         ` David Hildenbrand
2020-02-21 13:03           ` Christian Borntraeger
2020-02-21 13:08             ` David Hildenbrand
2020-02-21  8:22       ` [PATCH v3 " David Hildenbrand
2020-02-21  8:40         ` Christian Borntraeger
2020-02-21 11:47           ` David Hildenbrand
2020-02-20 10:39 ` [PATCH v3 10/37] KVM: s390: protvirt: Add KVM api documentation Christian Borntraeger
2020-02-20 13:05   ` David Hildenbrand
2020-02-20 13:55     ` Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 11/37] KVM: s390: protvirt: Secure memory is not mergeable Christian Borntraeger
2020-02-21 12:49   ` Cornelia Huck
2020-02-20 10:39 ` [PATCH v3 12/37] KVM: s390/mm: Make pages accessible before destroying the guest Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 13/37] KVM: s390: protvirt: Handle SE notification interceptions Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 14/37] KVM: s390: protvirt: Instruction emulation Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 15/37] KVM: s390: protvirt: Implement interrupt injection Christian Borntraeger
2020-02-20 10:39 ` [PATCH v3 16/37] KVM: s390: protvirt: Add SCLP interrupt handling Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 17/37] KVM: s390: protvirt: Handle spec exception loops Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 18/37] KVM: s390: protvirt: Add new gprs location handling Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 19/37] KVM: S390: protvirt: Introduce instruction data area bounce buffer Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 20/37] KVM: s390: protvirt: handle secure guest prefix pages Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 21/37] KVM: s390/mm: handle guest unpin events Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 22/37] KVM: s390: protvirt: Write sthyi data to instruction data area Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 23/37] KVM: s390: protvirt: STSI handling Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 24/37] KVM: s390: protvirt: disallow one_reg Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 25/37] KVM: s390: protvirt: Do only reset registers that are accessible Christian Borntraeger
2020-02-21 10:39   ` David Hildenbrand
2020-02-20 10:40 ` [PATCH v3 26/37] KVM: s390: protvirt: Only sync fmt4 registers Christian Borntraeger
2020-02-21 10:43   ` David Hildenbrand
2020-02-20 10:40 ` [PATCH v3 27/37] KVM: s390: protvirt: Add program exception injection Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 28/37] KVM: s390: protvirt: UV calls in support of diag308 0, 1 Christian Borntraeger
2020-02-21 10:44   ` David Hildenbrand
2020-02-20 10:40 ` [PATCH v3 29/37] KVM: s390: protvirt: Report CPU state to Ultravisor Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 30/37] KVM: s390: protvirt: Support cmd 5 operation state Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 31/37] KVM: s390: protvirt: Mask PSW interrupt bits for interception 104 and 112 Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 32/37] KVM: s390: protvirt: do not inject interrupts after start Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 33/37] KVM: s390: protvirt: Add UV cpu reset calls Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 34/37] DOCUMENTATION: Protected virtual machine introduction and IPL Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 35/37] s390: protvirt: Add sysfs firmware interface for Ultravisor information Christian Borntraeger
2020-02-21 10:46   ` David Hildenbrand
2020-02-20 10:40 ` [PATCH v3 36/37] KVM: s390: rstify new ioctls in api.rst Christian Borntraeger
2020-02-21 10:47   ` David Hildenbrand
2020-02-21 10:51   ` Cornelia Huck
2020-02-21 11:13     ` Christian Borntraeger
2020-02-20 10:40 ` [PATCH v3 37/37] KVM: s390: protvirt: introduce and enable KVM_CAP_S390_PROTECTED Christian Borntraeger
2020-02-21 10:47   ` David Hildenbrand
2020-02-21 10:54 ` [PATCH v3 00/37] KVM: s390: Add support for protected VMs David Hildenbrand
2020-02-21 11:26   ` Christian Borntraeger
2020-02-21 11:28     ` David Hildenbrand
2020-02-21 13:45       ` Cornelia Huck

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