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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Andy Lutomirski <luto@kernel.org>, <x86@kernel.org>
Cc: Juergen Gross <jgross@suse.com>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH entry v2 5/6] x86/ldt: Disable 16-bit segments on Xen PV
Date: Fri, 3 Jul 2020 20:00:34 +0100
Message-ID: <87fc68cf-540a-85e1-4dde-80cb3e82c3a5@citrix.com> (raw)
In-Reply-To: <92b2975459dfe5929ecf34c3896ad920bd9e3f2d.1593795633.git.luto@kernel.org>

On 03/07/2020 18:02, Andy Lutomirski wrote:
> Xen PV doesn't implement ESPFIX64, so they don't work right.  Disable
> them.  Also print a warning the first time anyone tries to use a
> 16-bit segment on a Xen PV guest that would otherwise allow it
> to help people diagnose this change in behavior.
>
> This gets us closer to having all x86 selftests pass on Xen PV.

Do we know exactly how much virtual address space ESPFIX64 takes up?

Are people going to scream in horror if Linux needs to donate some
virtual address space back to Xen to get this working?  Linux's current
hypervisor range (8TB, 16 pagetable slots) really isn't enough for some
systems these days.

~Andrew

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-03 17:02 [PATCH entry v2 0/6] x86/entry: Fixes and cleanups Andy Lutomirski
2020-07-03 17:02 ` [PATCH entry v2 1/6] x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER Andy Lutomirski
2020-07-04 17:49   ` [tip: x86/urgent] " tip-bot2 for Andy Lutomirski
2020-07-03 17:02 ` [PATCH entry v2 2/6] x86/entry, selftests: Further improve user entry sanity checks Andy Lutomirski
2020-07-04 17:49   ` [tip: x86/urgent] " tip-bot2 for Andy Lutomirski
2020-08-20 10:23     ` peterz
2020-08-22 21:59       ` Andy Lutomirski
2020-07-03 17:02 ` [PATCH entry v2 3/6] x86/entry/xen: Route #DB correctly on Xen PV Andy Lutomirski
2020-07-04 17:49   ` [tip: x86/urgent] " tip-bot2 for Andy Lutomirski
2020-07-06  8:41   ` [PATCH entry v2 3/6] " Michal Kubecek
2020-07-06  8:57     ` Jürgen Groß
2020-07-06  9:32       ` Michal Kubecek
2020-07-03 17:02 ` [PATCH entry v2 4/6] x86/entry/32: Fix #MC and #DB wiring on x86_32 Andy Lutomirski
2020-07-04 17:49   ` [tip: x86/urgent] " tip-bot2 for Andy Lutomirski
2020-07-03 17:02 ` [PATCH entry v2 5/6] x86/ldt: Disable 16-bit segments on Xen PV Andy Lutomirski
2020-07-03 19:00   ` Andrew Cooper [this message]
2020-07-04 17:49   ` [tip: x86/urgent] " tip-bot2 for Andy Lutomirski
2020-07-03 17:02 ` [PATCH entry v2 6/6] x86/entry: Rename idtentry_enter/exit_cond_rcu() to idtentry_enter/exit() Andy Lutomirski
2020-07-07  8:23   ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-07-03 17:31 ` [PATCH entry v2 0/6] x86/entry: Fixes and cleanups Peter Zijlstra

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