From: "Roger Pau Monné" <roger.pau@citrix.com>
To: David Vrabel <david.vrabel@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: A couple of HVMlite loose ends
Date: Wed, 13 Jan 2016 17:07:38 +0100 [thread overview]
Message-ID: <5696764A.1000804@citrix.com> (raw)
In-Reply-To: <5696733D.6080500@citrix.com>
El 13/01/16 a les 16.54, David Vrabel ha escrit:
> On 13/01/16 15:49, Roger Pau Monné wrote:
>> 2. HVM MTRR and Dom0.
>>
>> MTRR ranges are initialised from hvmloader, which means that although we
>> expose the MTRR functionality to HVMlite guests (and AFAICT the
>> functionality is fully complete/usable), the initial state in which a
>> guest finds the MTRR ranges is not expected, leading to errors. Again, I
>> see three ways to solve this:
>>
>> a) Mask the MTRR functionality from CPUID for HVMlite guests. This
>> requires adding a XEN_X86_EMU_MTRR flag to the bitmap introduced in arch
>> domain.
>
> I'd favour this approach I think, depending on if any changes were
> needed in guests to support this (I assume not?).
No, AFAIK PAT works perfectly fine on HVMlite, but IIRC MTRR is
mandatory on amd64 CPUs (although almost nobody uses it).
> Guests should use PAT instead.
This is a far shoot, but HVMlite guests are not required to run with
paging enabled, and as so we should provide ways to set memory
attributes taking that into account IMHO.
Roger.
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next prev parent reply other threads:[~2016-01-13 16:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-13 15:49 A couple of HVMlite loose ends Roger Pau Monné
2016-01-13 15:54 ` David Vrabel
2016-01-13 16:07 ` Roger Pau Monné [this message]
2016-01-13 16:10 ` Jan Beulich
2016-01-13 15:56 ` Juergen Gross
2016-01-13 16:01 ` Roger Pau Monné
2016-01-13 16:05 ` Juergen Gross
2016-01-13 16:13 ` Jan Beulich
2016-01-13 16:17 ` Andrew Cooper
2016-01-13 16:26 ` Jan Beulich
2016-01-13 16:30 ` Andrew Cooper
2016-01-13 17:03 ` Boris Ostrovsky
2016-01-13 17:14 ` Andrew Cooper
2016-01-13 16:14 ` Andrew Cooper
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