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From: Andrii Anisov <andrii.anisov@gmail.com>
To: "Julien Grall" <julien.grall@arm.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	"LOPEZ, FUENTES NACARINO Jairo Eduardo" <jairo@ruri.waseda.jp>,
	xen-devel@lists.xen.org
Subject: Re: RT Xen on ARM - R-Car series
Date: Mon, 4 Feb 2019 16:46:25 +0200	[thread overview]
Message-ID: <d6a0a44c-4d82-4e3f-b70c-8909e7941f06@gmail.com> (raw)
In-Reply-To: <015ee6f9-3ce0-d579-78e0-7f8502e0f447@arm.com>



On 04.02.19 13:21, Julien Grall wrote:
> What I meant is the virtual address stays the same but the guest physical address may change. I don't see how this could be broken today, can you explain it?

I suppose guest's mapping change is not quite atomic from the hypervisor point of view, so domain could be caught in the middle.

> 
>> Moreover, having that buffer mapped to XEN will reduce context switch time as a side effect.
> 
> I am still unsure whether we really want to keep that always mapped.
> 
> Each guest can support up to 128 vCPUs. So we would have 128 runstates mapped. Each runstate would take up to 2 pages. This means that each guest would require up to 1MB of vmap.

Here buffer allocation on XEN side might benefit, even aligning/fitting the runstate into one page might work. But I understand it is undesirable and requires lot of changes

> I thought more about it during the week-end. I would actually not implement get_gfn but implement a function similar to get_page_from_gva on x86. The reason behind this is the function on Arm is quite complex as it caters many different use case.

I'll look into this. But I have to massage my yocto first.

-- 
Sincerely,
Andrii Anisov.

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  reply	other threads:[~2019-02-04 14:46 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CACrvCsaeHuwzZzUQTzNYF7fqmgQWNJUVOQZv9D0MnYrXjqzZtQ@mail.gmail.com>
2018-12-22 12:21 ` RT Xen on ARM - R-Car series Andrii Anisov
2018-12-25 16:07   ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2018-12-27 11:07     ` Andrii Anisov
2018-12-28 15:22       ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2018-12-28  8:28         ` Andrii Anisov
2018-12-28  8:32           ` Andrii Anisov
2018-12-28  8:39           ` Andrii Anisov
2019-01-04  9:09             ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-08 17:04               ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-11 20:12                 ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-14  8:42                   ` Andrii Anisov
2019-01-16  7:53                   ` Andrii Anisov
2019-01-21 18:04                     ` LOPEZ, FUENTES NACARINO Jairo Eduardo
     [not found]                     ` <CACrvCsZB-tps6=Vr=1Phf5oo5eUReabMLJzkbO3d2hmNLDOxww@mail.gmail.com>
     [not found]                       ` <7e217489-2c1a-c35f-d51f-0969654aa8cc@gmail.com>
     [not found]                         ` <CACrvCsaYJ-zGkZwfdV7BXDABW8u_EDQetU3pq+2otRGXWTXagw@mail.gmail.com>
     [not found]                           ` <4d078801-b804-06e7-ad5c-8032b1dbaa84@gmail.com>
2019-01-28 17:20                             ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-28  8:25                               ` Andrii Anisov
2019-01-29 15:30                                 ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-29 13:29                                   ` Andrii Anisov
2019-01-30 20:23                                     ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2019-01-30 12:12                                       ` Julien Grall
2019-01-31 11:22                                         ` Andrii Anisov
2019-01-31 11:37                                           ` Julien Grall
2019-01-31 12:00                                             ` Andrii Anisov
2019-01-31 12:20                                               ` Julien Grall
2019-01-31 21:56                                                 ` Stefano Stabellini
2019-01-31 23:14                                                   ` Julien Grall
2019-02-01 10:02                                                     ` Andrii Anisov
2019-02-01 10:12                                                       ` Julien Grall
2019-02-01 10:35                                                         ` Andrii Anisov
2019-02-01 11:06                                                           ` Julien Grall
2019-02-01 16:53                                                     ` Roger Pau Monné
2019-02-01 17:40                                                       ` Julien Grall
2019-02-04 10:28                                                         ` Andrii Anisov
2019-02-04 11:21                                                           ` Julien Grall
2019-02-04 14:46                                                             ` Andrii Anisov [this message]
2019-02-04 15:05                                                               ` Julien Grall
2019-02-04 12:53                                                         ` Roger Pau Monné
2019-02-04 21:58                                                           ` Julien Grall
2019-02-05  8:40                                                             ` Andrii Anisov
2019-02-05  9:45                                                               ` Roger Pau Monné
2019-02-05  9:54                                                                 ` Andrii Anisov
2019-02-05 10:10                                                                   ` Roger Pau Monné
2019-02-06 20:20                                                               ` Andrii Anisov
2019-02-06 21:03                                                                 ` Stefano Stabellini
2019-02-07  9:42                                                                   ` Andrii Anisov
2019-02-07 10:35                                                                     ` Roger Pau Monné
2019-02-07 10:59                                                                       ` Julien Grall
2019-02-12 18:21                                                                         ` Andrii Anisov
2019-02-12 19:21                                                                           ` Julien Grall
2019-02-14 14:18                                                                             ` Andrii Anisov
2019-02-14 17:29                                                                               ` Julien Grall
2019-02-15 11:30                                                                                 ` Andrii Anisov
2019-02-15 17:13                                                                                   ` Julien Grall
2019-02-15 17:41                                                                                     ` Andrii Anisov
2019-02-16  8:42                                                                                       ` Julien Grall
2019-02-12 18:21                                                                       ` Andrii Anisov
2019-02-14 16:29                                                                         ` Roger Pau Monné
2019-02-15 15:21                                                                           ` Andrii Anisov
2019-02-15 16:31                                                                             ` Julien Grall
2019-02-15 17:30                                                                               ` Andrii Anisov
2019-02-15 18:36                                                                                 ` Julien Grall
2019-02-14 17:08                                                                         ` Julien Grall
2019-02-05  9:26                                                             ` Roger Pau Monné
2019-02-01 10:07                                                   ` Andrii Anisov
2019-02-01 10:16                                                     ` Julien Grall
2019-02-01 10:35                                                       ` Andrii Anisov
2019-02-01 10:51                                                         ` Julien Grall
2019-02-01 18:00                                                           ` Stefano Stabellini
2019-02-04 10:32                                                           ` Andrii Anisov
2019-02-04 11:36                                                             ` Julien Grall
2019-02-04 15:19                                                               ` Andrii Anisov
2019-02-04 22:06                                                                 ` Julien Grall
2019-02-05  9:01                                                                   ` Andrii Anisov
2019-02-05 19:18                                                                     ` Stefano Stabellini
2019-02-07 10:53                                                                       ` Andrii Anisov
     [not found]                                         ` <CACrvCsbkFG=3To83qi7xxmtmgC_9PKvuLz73edhiaV7TsJAZqQ@mail.gmail.com>
2019-01-31 12:24                                           ` Julien Grall
2019-01-16 20:46                   ` Andrii Anisov
2019-01-16  7:40                 ` Andrii Anisov
2019-01-17  2:08                   ` LOPEZ, FUENTES NACARINO Jairo Eduardo
2018-12-28 17:35         ` LOPEZ, FUENTES NACARINO Jairo Eduardo

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