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From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.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: Wed, 3 May 2017 12:43:02 +0100	[thread overview]
Message-ID: <20170503114302.faygqpmv4buppwsd@citrix.com> (raw)
In-Reply-To: <da2d5f1a-f134-bc17-dda2-84c4472af7cf@citrix.com>

On Wed, May 03, 2017 at 12:38:15PM +0100, Andrew Cooper wrote:
> On 03/05/17 12:26, Wei Liu wrote:
> > On Wed, May 03, 2017 at 03:02:25AM -0600, Jan Beulich wrote:
> >>>>> On 02.05.17 at 20:05, <andrew.cooper3@citrix.com> wrote:
> >>> --- /dev/null
> >>> +++ b/xen/arch/x86/pv/traps.c
> >>> @@ -0,0 +1,44 @@
> >>> +/******************************************************************************
> >>> + * arch/x86/pv/traps.c
> >>> + *
> >>> + * PV low level entry points.
> >>> + *
> >>> + * This program is free software; you can redistribute it and/or modify
> >>> + * it under the terms of the GNU General Public License as published by
> >>> + * the Free Software Foundation; either version 2 of the License, or
> >>> + * (at your option) any later version.
> >>> + *
> >>> + * This program is distributed in the hope that it will be useful,
> >>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> >>> + * GNU General Public License for more details.
> >>> + *
> >>> + * You should have received a copy of the GNU General Public License
> >>> + * along with this program; If not, see <http://www.gnu.org/licenses/>.
> >>> + *
> >>> + * Copyright (c) 2017 Citrix Systems Ltd.
> >>> + */
> >>> +
> >>> +#include <xen/hypercall.h>
> >>> +
> >>> +#include <asm/apic.h>
> >>> +
> >>> +#ifdef CONFIG_COMPAT
> >> As expressed before, I disagree to the re-introduction of such
> >> conditionals in x86 code.
> >>
> > I'm curious to know how the COMPAT interface is treated long term.
> >
> > I guess you're of the opinion that we should always have them enabled?
> 
> There is a valid usecase to disable CONFIG_COMPAT, seeing as sufficient
> PVH interfaces exist to start APs straight in 64bit mode, as it provides
> a meaningful reduction in hypervisor attack surface.
> 

I agree.

> As it is a configurable option, I intend to work in a direction which
> eventually makes it usable under x86.
> 
> If there is a wish to move in an opposite direction, that should be a
> separate discussion made over a patch removing its entry from
> common/Kconfig.
> 

Yes, I think a proper discussion is needed to clarify the future
direction.

Wei.

> ~Andrew

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  reply	other threads:[~2017-05-03 11:43 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 [this message]
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
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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