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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 5/7] x86/traps: Lift all non-entrypoint logic in entry_int82() up into C
Date: Thu, 4 May 2017 10:27:16 +0100	[thread overview]
Message-ID: <0be8b6da-1537-37a8-1cb7-e001f3b3dc44@citrix.com> (raw)
In-Reply-To: <590AF406020000780015698B@prv-mh.provo.novell.com>

On 04/05/17 08:27, Jan Beulich wrote:
>>>> On 03.05.17 at 20:29, <andrew.cooper3@citrix.com> wrote:
>> Irrespective of the history which lead to this point, the important
>> question is whether we want to allow compiling x86 without CONFIG_COMPAT.
>>
>> If the eventual decision is yes, then new code should specifically be
>> introduced as being CONFIG_COMPAT-clean, because decisions like that
>> affect how to structure the code in the first place, and therefore be
>> far cleaner changes than trying to retrofit CONFIG_COMPAT in the future.
> Well, okay, I can agree with this. So what would an x86-Xen with
> COMPAT off support? 64-bit guests only, regardless of type?

Yes.  I intend this to mean 64bit guests of any type.

> As said before, I don't view it as a reasonable setup to allow only
> 64-bit HVM guests, so unless there is an intention to have a
> configuration where only PVH guests are supported (i.e. neither
> PV nor traditional HVM), I don't think allowing the option to be
> turned off makes sense on x86.

HVM and PVH aren't very different, but there will be a small amount of
work required to get plain HVM booting like this, because of hvmloader
currently being 32bit only.  I do see (potentially) value in allowing
64bit-only traditional HVM guests, e.g. with a 64bit OVMF firmware
(although this is already turning fairly PVH in nature).

PVH on the other hand is already capable of booting and running properly
were CONFIG_COMPAT to be disabled today.

The selection of CONFIG_PV, CONFIG_HVM and CONFIG_COMPAT will eventually
define the matrix of which guests are supported in this build of the
hypervisor, based on which chunks of functionality they compile out.

~Andrew

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  reply	other threads:[~2017-05-04  9:27 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-02 18:05 [PATCH 0/7] XSAs 213-315 followups Andrew Cooper
2017-05-02 18:05 ` [PATCH 1/7] x86/traps: Drop 32bit fields out of tss_struct Andrew Cooper
2017-05-03  8:10   ` Jan Beulich
2017-05-03 12:33     ` Andrew Cooper
2017-05-03  9:48   ` Wei Liu
2017-05-02 18:05 ` [PATCH 2/7] x86/traps: Poison unused stack pointers in the TSS Andrew Cooper
2017-05-03  8:14   ` Jan Beulich
2017-05-03 12:47     ` Andrew Cooper
2017-05-03 13:29   ` [PATCH v2 " Andrew Cooper
2017-05-03 13:45     ` Jan Beulich
2017-05-02 18:05 ` [PATCH 3/7] x86/mm: Further restrict permissions on some virtual mappings Andrew Cooper
2017-05-03  8:49   ` Jan Beulich
2017-05-03 13:38     ` Andrew Cooper
2017-05-03 13:48       ` Jan Beulich
2017-05-03  9:48   ` Wei Liu
2017-05-03 10:11   ` Tim Deegan
2017-05-03 11:13   ` George Dunlap
2017-05-02 18:05 ` [PATCH 4/7] x86/traps: Rename compat_hypercall() to entry_int82() Andrew Cooper
2017-05-03  8:55   ` Jan Beulich
2017-05-03 13:41     ` Andrew Cooper
2017-05-02 18:05 ` [PATCH 5/7] x86/traps: Lift all non-entrypoint logic in entry_int82() up into C Andrew Cooper
2017-05-03  9:02   ` Jan Beulich
2017-05-03 11:26     ` Wei Liu
2017-05-03 11:38       ` Andrew Cooper
2017-05-03 11:43         ` Wei Liu
2017-05-03 12:02         ` Jan Beulich
2017-05-03 12:18           ` Andrew Cooper
2017-05-03 12:37             ` Jan Beulich
2017-05-03 18:29               ` Andrew Cooper
2017-05-04  7:27                 ` Jan Beulich
2017-05-04  9:27                   ` Andrew Cooper [this message]
2017-05-04  9:36                     ` Jan Beulich
2017-05-04  9:57                       ` Andrew Cooper
2017-05-03 12:00       ` Jan Beulich
2017-05-04 10:01     ` [PATCH v2 " Andrew Cooper
2017-05-04 10:16       ` Andrew Cooper
2017-05-04 10:28         ` Jan Beulich
2017-05-04 11:09           ` Andrew Cooper
2017-05-04 10:22       ` Jan Beulich
2017-05-02 18:05 ` [PATCH 6/7] x86/asm: Fold LOAD_C_CLOBBERED into RESTORE_ALL Andrew Cooper
2017-05-03  9:08   ` Jan Beulich
2017-05-03  9:48   ` Wei Liu
2017-05-02 18:05 ` [PATCH 7/7] x86/asm: Clobber %r{8..15} on exit to 32bit PV guests Andrew Cooper
2017-05-03  9:13   ` Jan Beulich
2017-05-03 17:51     ` [PATCH v2 " Andrew Cooper
2017-05-04  8:50       ` Jan Beulich
2017-05-04 11:11 ` [RFC for 4.9] [PATCH 0/7] XSAs 213-315 followups Andrew Cooper
2017-05-04 12:52   ` Julien Grall

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