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From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.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, 04 May 2017 03:36:47 -0600	[thread overview]
Message-ID: <590B124F0200007800156B02@prv-mh.provo.novell.com> (raw)
In-Reply-To: <0be8b6da-1537-37a8-1cb7-e001f3b3dc44@citrix.com>

>>> On 04.05.17 at 11:27, <andrew.cooper3@citrix.com> wrote:
> On 04/05/17 08:27, Jan Beulich wrote:
>> 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).

So that would then be yet another construct with no raw hardware
equivalent. I'd prefer if we strove for improving our compatibility with
raw hardware (as we do in various other places, you being one of
the primary advocates to do so) instead of inventing new custom
environments. Furthermore, while I can see the benefit of e.g. not
allowing PV guests for security reasons, I'm having a hard time
imagining some security benefit from disallowing a HVM guest to run
in 32-bit mode. But perhaps you've thought of something already...

Jan


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  reply	other threads:[~2017-05-04  9:36 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
2017-05-04  9:36                     ` Jan Beulich [this message]
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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