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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: "Martin Pohlack" <mpohlack@amazon.de>,
	"Julien Grall" <julien.grall@arm.com>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Joao Martins" <joao.m.martins@oracle.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Daniel Kiper" <daniel.kiper@oracle.com>,
	"Marek Marczykowski" <marmarek@invisiblethingslab.com>,
	"Anthony Liguori" <aliguori@amazon.com>,
	Xen-devel <xen-devel@lists.xenproject.org>,
	"Dannowski, Uwe" <uwed@amazon.de>,
	"Lars Kurth" <lars.kurth@citrix.com>,
	"Konrad 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>,
	"Mihai Donțu" <mdontu@bitdefender.com>,
	"Woodhouse, David" <dwmw@ama>
Subject: Re: Reducing or removing direct map from xen (was Re: Ongoing/future speculative mitigation work)
Date: Thu, 21 Feb 2019 10:59:41 +0100	[thread overview]
Message-ID: <20190221095941.6ssrgwiugcr7vtb3@Air-de-Roger> (raw)
In-Reply-To: <20190220170809.jr6neinf5beescf4@zion.uk.xensource.com>

On Wed, Feb 20, 2019 at 05:08:09PM +0000, Wei Liu wrote:
> On Wed, Feb 20, 2019 at 01:09:56PM +0000, Wei Liu wrote:
> [...]
> > I think under-allocate-then-map looks plausible. xmalloc will need
> > to allocate pages, put them into an array and call __vmap on that array
> > directly.
> 
> The biggest issue with this approach is that we now need an array of
> 1UL<<MAX_ORDER to accommodate mfns. Back of envelope calculation: on x86
> this is going to be (1UL<<20)*8 bytes long. This is not feasible.

Right. I guess the only remaining option is to allocate a virtual
address space and populate it using multiple pages?

That would likely require to split some functions into smaller helpers
so you can call them and provide the virtual address where a page
should be mapped?

Roger.

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  reply	other threads:[~2019-02-21 10:00 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
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 [this message]
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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