From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Andres Lagar-Cavilla" <andres@lagarcavilla.org>
Subject: Re: [PATCH 3 of 7] Use a reserved pfn in the guest
 address space to store mem event rings
Date: Wed, 29 Feb 2012 18:29:41 -0800
Message-ID: <887ce3ccdd85d6cf46de1e577b3c18d3.squirrel@webmail.lagarcavilla.org>
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Ian Jackson <ian.jackson@eu.citrix.com>, "andres@gridcentric.ca" <andres@gridcentric.ca>, "Tim (Xen.org)" <tim@xen.org>, "keir.xen@gmail.com" <keir.xen@gmail.com>, "adin@gridcentric.ca" <adin@gridcentric.ca>
List-Id: xen-devel@lists.xenproject.org

> On Thu, 2012-02-23 at 06:05 +0000, Andres Lagar-Cavilla wrote:
>
> Doers this mean that a guest can now potentially observe, or even modify
> it's own mem event ring? Are we sure there's no potential for havoc
> here?
>
> Is there no scope for making these pages owned by the domain but not
> actually part of the P2M? We can cope with that for other types of magic
> page, can't we?
>
> I didn't atually dig into the implementation other than to see if it
> answered  my questions, although I did notice:

Ian, I'll resend now including the recent Acked-by's and your two
tools-side comments. We can work from there, and hopefully remove this
blocker in the 4.2 todo list in short order.

Thanks!
Andres

>
>> diff -r 99e6c9b9e971 -r 0e79f8005b6b tools/libxc/xc_hvm_build.c
>> --- a/tools/libxc/xc_hvm_build.c
>> +++ b/tools/libxc/xc_hvm_build.c
>> @@ -38,12 +38,15 @@
>>  #define SUPERPAGE_1GB_SHIFT   18
>>  #define SUPERPAGE_1GB_NR_PFNS (1UL << SUPERPAGE_1GB_SHIFT)
>>
>> -#define SPECIALPAGE_BUFIOREQ 0
>> -#define SPECIALPAGE_XENSTORE 1
>> -#define SPECIALPAGE_IOREQ    2
>> -#define SPECIALPAGE_IDENT_PT 3
>> -#define SPECIALPAGE_CONSOLE  4
>> -#define NR_SPECIAL_PAGES     5
>> +#define SPECIALPAGE_PAGING   0
>> +#define SPECIALPAGE_ACCESS   1
>> +#define SPECIALPAGE_SHARING  2
>> +#define SPECIALPAGE_BUFIOREQ 3
>> +#define SPECIALPAGE_XENSTORE 4
>> +#define SPECIALPAGE_IOREQ    5
>> +#define SPECIALPAGE_IDENT_PT 6
>> +#define SPECIALPAGE_CONSOLE  7
>> +#define NR_SPECIAL_PAGES     8
>
> Any reason to not simply append them?
>
> Ian.
>
>