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Re: [Xen-devel] [PATCH] mm: option to _always_ scrub freed domheap pages
- To: Jan Beulich <JBeulich@xxxxxxxx>, Eslam Elnikety <elnikety@xxxxxxxxxx>
- From: George Dunlap <george.dunlap@xxxxxxxxxx>
- Date: Tue, 7 May 2019 12:21:38 +0100
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wei.liu2@xxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, Julien Grall <julien.grall@xxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Tue, 07 May 2019 11:22:26 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Openpgp: preference=signencrypt
On 5/7/19 11:03 AM, Jan Beulich wrote:
>>>> On 07.05.19 at 11:55, <george.dunlap@xxxxxxxxxx> wrote:
>> On 5/6/19 1:46 PM, Eslam Elnikety wrote:
>> [...]
>> I'm wondering if this should default to 'true', and people who really
>> want the extra performance should turn it off.
>
> Why would we want to cater for buggy guests by default?
Because one of the big selling points for Xen is that it is more secure;
and one of the points of virtualization is to run guests for which you
have no option of changing or upgrading. Having an extra safety catch
to prevent loss of data *even in the case of buggy guests* on by default
is on-brand for us.
That said, the suggestion was predicated on my rather vague impression
that XenServer has been doing this by default for years now, and thus
has been proven to not be terribly problematic performance-wise. If
that's not the case, then off-by-default might be a better option.
-George
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