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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: QingFeng Hao <haoqf@linux.vnet.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
	kvm@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jon Masters <jcm@redhat.com>, Marcus Meissner <meissner@suse.de>,
	Jiri Kosina <jkosina@suse.cz>
Subject: Re: [PATCH 6/6] s390: scrub registers on kernel entry and KVM exit
Date: Fri, 19 Jan 2018 08:57:51 +0100	[thread overview]
Message-ID: <d3950440-d76f-dee4-1e30-9f287dc18fd2@de.ibm.com> (raw)
In-Reply-To: <e0d91f92-a9b5-f602-3f81-334b7ff381d9@linux.vnet.ibm.com>



On 01/19/2018 07:29 AM, QingFeng Hao wrote:
> 
> 
> 在 2018/1/17 17:48, Martin Schwidefsky 写道:
>> Clear all user space registers on entry to the kernel and all KVM guest
>> registers on KVM guest exit if the register does not contain either a
>> parameter or a result value.
> I am not sure if I understand this but it will be safer?

It ist similar to commit 0cb5b30698fd ("kvm: vmx: Scrub hardware GPRs at VM-exit").
The idea is to minimize potential payload channels.

> And can we abstract the operations to be a macro like CLEAR_REG_7?

No, please.
xgr %r7,%r7
is absolutely clear what it does, a MACRO often is not.

  reply	other threads:[~2018-01-19  7:57 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17  9:48 [PATCH 0/6] s390: improve speculative execution handling Martin Schwidefsky
2018-01-17  9:48 ` [PATCH 1/6] s390/alternative: use a copy of the facility bit mask Martin Schwidefsky
2018-01-17 13:54   ` David Hildenbrand
2018-01-17 14:24   ` Cornelia Huck
2018-01-17  9:48 ` [PATCH 2/6] s390: implement nospec_[load|ptr] Martin Schwidefsky
2018-01-17 12:41   ` Jiri Kosina
2018-01-17 14:52     ` Jon Masters
2018-01-17 13:58   ` David Hildenbrand
2018-01-17 14:04     ` Christian Borntraeger
2018-01-17  9:48 ` [PATCH 3/6] s390: add options to change branch prediction behaviour for the kernel Martin Schwidefsky
2018-01-18  9:52   ` Cornelia Huck
2018-01-19  4:53   ` QingFeng Hao
2018-01-17  9:48 ` [PATCH 4/6] s390: add system call to run tasks with modified branch prediction Martin Schwidefsky
2018-01-17 10:03   ` Florian Weimer
2018-01-17 10:05     ` Paolo Bonzini
2018-01-17 11:14     ` Christian Borntraeger
2018-01-17 11:50       ` Paolo Bonzini
2018-01-17 11:55       ` Martin Schwidefsky
2018-01-17 13:25         ` Heiko Carstens
2018-01-17  9:48 ` [PATCH 5/6] KVM: s390: wire up seb feature Martin Schwidefsky
2018-01-17 11:18   ` Christian Borntraeger
2018-01-17 11:22     ` Paolo Bonzini
2018-01-17 11:28       ` Christian Borntraeger
2018-01-17 11:29         ` Christian Borntraeger
2018-01-17 11:32           ` Paolo Bonzini
2018-01-17 11:33   ` David Hildenbrand
2018-01-17 11:39     ` Christian Borntraeger
2018-01-17 13:44   ` [PATCH v2] KVM: s390: wire up bpb feature Christian Borntraeger
2018-01-17 13:51     ` David Hildenbrand
2018-01-17 21:43       ` Christian Borntraeger
2018-01-18  6:27         ` Martin Schwidefsky
2018-01-18  9:59     ` Cornelia Huck
2018-01-18 10:09       ` Christian Borntraeger
2018-01-17  9:48 ` [PATCH 6/6] s390: scrub registers on kernel entry and KVM exit Martin Schwidefsky
2018-01-19  6:29   ` QingFeng Hao
2018-01-19  7:57     ` Christian Borntraeger [this message]
2018-01-19  8:27       ` QingFeng Hao
2018-01-17 12:00 ` [PATCH 0/6] s390: improve speculative execution handling Cornelia Huck
2018-01-17 12:05   ` Christian Borntraeger
2018-01-17 13:29 ` Greg Kroah-Hartman

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