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From: George Dunlap <george.dunlap@citrix.com>
To: Jan Beulich <JBeulich@suse.com>, Wei Liu <wei.liu2@citrix.com>
Cc: Martin Pohlack <mpohlack@amazon.de>,
	Julien Grall <julien.grall@arm.com>,
	Joao Martins <joao.m.martins@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Mihai Dontu <mdontu@bitdefender.com>,
	Marek Marczykowski <marmarek@invisiblethingslab.com>,
	Anthony Liguori <aliguori@amazon.com>,
	uwed@amazon.de, Lars Kurth <lars.kurth@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Ross Philipson <ross.philipson@oracle.com>,
	Dario Faggioli <dfaggioli@suse.com>, Matt Wilson <msw@amazon.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	Sergey Dyasli <sergey.dyasli@citrix.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel List <xen-devel@lists.xen.org>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: Ongoing/future speculative mitigation work
Date: Thu, 25 Oct 2018 15:56:50 +0100	[thread overview]
Message-ID: <187f3a6a-e83e-3dc2-0cb7-69fecdacacf1@citrix.com> (raw)
In-Reply-To: <5BD1D82402000078001F4B60@prv1-mh.provo.novell.com>

On 10/25/2018 03:50 PM, Jan Beulich wrote:
>>>> On 22.10.18 at 16:55, <wei.liu2@citrix.com> wrote:
>> On Thu, Oct 18, 2018 at 06:46:22PM +0100, Andrew Cooper wrote:
>>> An easy first step here is to remove Xen's directmap, which will mean
>>> that guests general RAM isn't mapped by default into Xen's address
>>> space.  This will come with some performance hit, as the
>>> map_domain_page() infrastructure will now have to actually
>>> create/destroy mappings, but removing the directmap will cause an
>>> improvement for non-speculative security as well (No possibility of
>>> ret2dir as an exploit technique).
>>
>> I have looked into making the "separate xenheap domheap with partial
>> direct map" mode (see common/page_alloc.c) work but found it not as
>> straight forward as it should've been.
>>
>> Before I spend more time on this, I would like some opinions on if there
>> is other approach which might be more useful than that mode.
> 
> How would such a split heap model help with L1TF, where the
> guest specifies host physical addresses in its vulnerable page
> table entries

I don't think it would.

> (and hence could spy at xenheap but - due to not
> being mapped - not domheap)?

Er, didn't follow this bit -- if L1TF is related to host physical
addresses, how does having a virtual mapping in Xen affect things in any
way?

 -George

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  reply	other threads:[~2018-10-25 14:56 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-18 17:46 Ongoing/future speculative mitigation work Andrew Cooper
2018-10-19  8:09 ` Dario Faggioli
2018-10-19 12:17   ` Andrew Cooper
2018-10-22  9:32     ` Mihai Donțu
2018-10-22 14:55 ` Wei Liu
2018-10-22 15:09   ` Woodhouse, David
2018-10-22 15:14     ` Andrew Cooper
2018-10-25 14:50   ` Jan Beulich
2018-10-25 14:56     ` George Dunlap [this message]
2018-10-25 15:02       ` Jan Beulich
2018-10-25 16:29         ` Andrew Cooper
2018-10-25 16:43           ` George Dunlap
2018-10-25 16:50             ` Andrew Cooper
2018-10-25 17:07               ` George Dunlap
2018-10-26  9:16           ` Jan Beulich
2018-10-26  9:28             ` Wei Liu
2018-10-26  9:56               ` Jan Beulich
2018-10-26 10:51                 ` George Dunlap
2018-10-26 11:20                   ` Jan Beulich
2018-10-26 11:24                     ` George Dunlap
2018-10-26 11:33                       ` Jan Beulich
2018-10-26 11:43                         ` George Dunlap
2018-10-26 11:45                           ` Jan Beulich
2018-12-11 18:05                     ` Wei Liu
     [not found]                       ` <FB70ABC00200007CA293CED3@prv1-mh.provo.novell.com>
2018-12-12  8:32                         ` Jan Beulich
2018-10-24 15:24 ` Tamas K Lengyel
2018-10-25 16:01   ` Dario Faggioli
2018-10-25 16:25     ` Tamas K Lengyel
2018-10-25 17:23       ` Dario Faggioli
2018-10-25 17:29         ` Tamas K Lengyel
2018-10-26  7:31           ` Dario Faggioli
2018-10-25 16:55   ` Andrew Cooper
2018-10-25 17:01     ` George Dunlap
2018-10-25 17:35       ` Tamas K Lengyel
2018-10-25 17:43         ` Andrew Cooper
2018-10-25 17:58           ` Tamas K Lengyel
2018-10-25 18:13             ` Andrew Cooper
2018-10-25 18:35               ` Tamas K Lengyel
2018-10-25 18:39                 ` Andrew Cooper
2018-10-26  7:49                 ` Dario Faggioli
2018-10-26 12:01                   ` Tamas K Lengyel
2018-10-26 14:17                     ` Dario Faggioli
2018-10-26 10:11               ` George Dunlap
2018-12-07 18:40 ` Wei Liu
2018-12-10 12:12   ` George Dunlap
2018-12-10 12:19     ` George Dunlap
2019-01-24 11:44 ` Reducing or removing direct map from xen (was Re: Ongoing/future speculative mitigation work) Wei Liu
2019-01-24 16:00   ` George Dunlap
2019-02-07 16:50   ` Wei Liu
2019-02-20 12:29   ` Wei Liu
2019-02-20 13:00     ` Roger Pau Monné
2019-02-20 13:09       ` Wei Liu
2019-02-20 17:08         ` Wei Liu
2019-02-21  9:59           ` Roger Pau Monné
2019-02-21 17:51             ` Wei Liu
2019-02-22 11:48           ` Jan Beulich
2019-02-22 11:50             ` Wei Liu
2019-02-22 12:06               ` Jan Beulich
2019-02-22 12:11                 ` Wei Liu
2019-02-22 12:47                   ` Jan Beulich
2019-02-22 13:19                     ` Wei Liu
     [not found]                       ` <158783E402000088A293CED3@prv1-mh.provo.novell.com>
2019-02-22 13:24                         ` Jan Beulich
2019-02-22 13:27                           ` Jan Beulich

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