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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Joerg Roedel <joro@8bytes.org>, Juergen Gross <jgross@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
	<x86@kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-mm@kvack.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Brian Gerst <brgerst@gmail.com>,
	David Laight <David.Laight@aculab.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Eduardo Valentin <eduval@amazon.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Will Deacon <will.deacon@arm.com>, <aliguori@amazon.com>,
	<daniel.gruss@iaik.tugraz.at>, <hughd@google.com>,
	<keescook@google.com>, Andrea Arcangeli <aarcange@redhat.com>,
	Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	<jroedel@suse.de>
Subject: Re: [PATCH 00/31 v2] PTI support for x86_32
Date: Fri, 9 Feb 2018 13:54:44 +0000	[thread overview]
Message-ID: <9ca8429b-4ae4-e009-69b0-c4945be41e65@citrix.com> (raw)
In-Reply-To: <20180209133507.GD16484@8bytes.org>

On 09/02/18 13:35, Joerg Roedel wrote:
> Hi Juergen,
>
> On Fri, Feb 09, 2018 at 01:11:42PM +0100, Juergen Gross wrote:
>> On 09/02/18 10:25, Joerg Roedel wrote:
>>> XENPV is also untested from my side, but I added checks to
>>> not do the stack switches in the entry-code when XENPV is
>>> enabled, so hopefully it works. But someone should test it,
>>> of course.
>> That's unfortunate. 32 bit XENPV kernel is vulnerable to Meltdown, too.
>> I'll have a look whether 32 bit XENPV is still working, though.
>>
>> Adding support for KPTI with Xen PV should probably be done later. :-)
> Not sure how much is missing to make it work there, one point is
> certainly to write the right stack into tss.sp0 for xenpv on 32bit. This
> write has a check to only happen for !xenpv.
>
> But let's first test the code as-is on XENPV and see if it still boots
> :)

IMO, the only sensible way to do KPTI + Xen PV is to have Xen to do the
pagetable switch for 32bit like we already do for 64bit guests.  All
context switches already pass through the hypervisor, and it saves the
guest having to make the updates itself (which will trap for auditing)
or having to juggle the set_stack_base() semantics.

~Andrew

  reply	other threads:[~2018-02-09 13:54 UTC|newest]

Thread overview: 93+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-09  9:25 [PATCH 00/31 v2] PTI support for x86_32 Joerg Roedel
2018-02-09  9:25 ` [PATCH 01/31] x86/asm-offsets: Move TSS_sp0 and TSS_sp1 to asm-offsets.c Joerg Roedel
2018-02-09  9:25 ` [PATCH 02/31] x86/entry/32: Rename TSS_sysenter_sp0 to TSS_entry_stack Joerg Roedel
2018-02-09  9:25 ` [PATCH 03/31] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Joerg Roedel
2018-02-09  9:25 ` [PATCH 04/31] x86/entry/32: Put ESPFIX code into a macro Joerg Roedel
2018-02-09  9:25 ` [PATCH 05/31] x86/entry/32: Unshare NMI return path Joerg Roedel
2018-02-09  9:25 ` [PATCH 06/31] x86/entry/32: Split off return-to-kernel path Joerg Roedel
2018-02-09  9:25 ` [PATCH 07/31] x86/entry/32: Restore segments before int registers Joerg Roedel
2018-02-09  9:25 ` [PATCH 08/31] x86/entry/32: Enter the kernel via trampoline stack Joerg Roedel
2018-02-09  9:25 ` [PATCH 09/31] x86/entry/32: Leave " Joerg Roedel
2018-02-09 17:05   ` Linus Torvalds
2018-02-09 17:17     ` Denys Vlasenko
2018-02-10 15:26       ` David Laight
2018-02-10 20:18         ` Linus Torvalds
2018-02-09 17:43     ` Andy Lutomirski
2018-02-09 19:06       ` Joerg Roedel
2018-02-09 19:02     ` Joerg Roedel
2018-02-09 19:17       ` Linus Torvalds
2018-02-09 19:25         ` Joerg Roedel
2018-02-09 19:48           ` Linus Torvalds
2018-02-10 15:41             ` David Laight
2018-02-09 19:30       ` Denys Vlasenko
2018-02-09  9:25 ` [PATCH 10/31] x86/entry/32: Introduce SAVE_ALL_NMI and RESTORE_ALL_NMI Joerg Roedel
2018-02-09  9:25 ` [PATCH 11/31] x86/entry/32: Add PTI cr3 switches to NMI handler code Joerg Roedel
2018-02-09  9:25 ` [PATCH 12/31] x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points Joerg Roedel
2018-02-27 19:18   ` Waiman Long
2018-03-01 12:03     ` Joerg Roedel
2018-03-01 13:34     ` Joerg Roedel
2018-03-01 14:33       ` Waiman Long
2018-03-01 16:50         ` Joerg Roedel
2018-03-01 18:24           ` Brian Gerst
2018-03-01 18:36             ` Dave Hansen
2018-03-01 18:38             ` Linus Torvalds
2018-03-02  9:10               ` Joerg Roedel
2018-03-16 20:55                 ` Andy Lutomirski
2018-03-02  9:07             ` Joerg Roedel
2018-02-09  9:25 ` [PATCH 13/31] x86/entry/32: Handle Entry from Kernel-Mode on Entry-Stack Joerg Roedel
2018-02-09  9:25 ` [PATCH 14/31] x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled Joerg Roedel
2018-02-09  9:25 ` [PATCH 15/31] x86/pgtable/32: Allocate 8k page-tables " Joerg Roedel
2018-02-09  9:25 ` [PATCH 16/31] x86/pgtable: Move pgdp kernel/user conversion functions to pgtable.h Joerg Roedel
2018-02-09  9:25 ` [PATCH 17/31] x86/pgtable: Move pti_set_user_pgd() " Joerg Roedel
2018-02-09  9:25 ` [PATCH 18/31] x86/pgtable: Move two more functions from pgtable_64.h " Joerg Roedel
2018-02-09  9:25 ` [PATCH 19/31] x86/mm/pae: Populate valid user PGD entries Joerg Roedel
2018-02-14  9:45   ` Juergen Gross
2018-02-14 10:00     ` Joerg Roedel
2018-02-09  9:25 ` [PATCH 20/31] x86/mm/pae: Populate the user page-table with user pgd's Joerg Roedel
2018-02-09 17:48   ` Andy Lutomirski
2018-02-09 19:09     ` Joerg Roedel
2018-02-09  9:25 ` [PATCH 21/31] x86/mm/legacy: " Joerg Roedel
2018-02-09  9:25 ` [PATCH 22/31] x86/mm/pti: Add an overflow check to pti_clone_pmds() Joerg Roedel
2018-02-09  9:25 ` [PATCH 23/31] x86/mm/pti: Define X86_CR3_PTI_PCID_USER_BIT on x86_32 Joerg Roedel
2018-02-09 17:42   ` Andy Lutomirski
2018-02-09  9:25 ` [PATCH 24/31] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level " Joerg Roedel
2018-02-09  9:25 ` [PATCH 25/31] x86/mm/dump_pagetables: Define INIT_PGD Joerg Roedel
2018-02-09  9:25 ` [PATCH 26/31] x86/pgtable/pae: Use separate kernel PMDs for user page-table Joerg Roedel
2018-02-09  9:25 ` [PATCH 27/31] x86/ldt: Reserve address-space range on 32 bit for the LDT Joerg Roedel
2018-02-09  9:25 ` [PATCH 28/31] x86/ldt: Define LDT_END_ADDR Joerg Roedel
2018-02-09  9:25 ` [PATCH 29/31] x86/ldt: Split out sanity check in map_ldt_struct() Joerg Roedel
2018-02-09  9:25 ` [PATCH 30/31] x86/ldt: Enable LDT user-mapping for PAE Joerg Roedel
2018-02-09  9:25 ` [PATCH 31/31] x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32 Joerg Roedel
2018-02-09 12:11 ` [PATCH 00/31 v2] PTI support " Juergen Gross
2018-02-09 13:35   ` Joerg Roedel
2018-02-09 13:54     ` Andrew Cooper [this message]
2018-02-09 17:47 ` Andy Lutomirski
2018-02-09 19:11   ` Joerg Roedel
2018-02-10  9:15     ` Adam Borowski
2018-02-10 20:22       ` Linus Torvalds
2018-02-11 10:59         ` Adam Borowski
2018-02-11 17:40           ` Mark D Rustad
2018-02-11 19:42             ` Andy Lutomirski
2018-02-11 20:14               ` Linus Torvalds
2018-02-11 22:12               ` James Bottomley
2018-02-11 22:30                 ` Andy Lutomirski
2018-02-11 23:47                   ` James Bottomley
2018-02-11 22:34               ` Pavel Machek
2018-02-11 23:25               ` Alan Cox
2018-02-12 10:16                 ` Anders Larsen
2018-02-14 10:43               ` Pavel Machek
2018-02-13  8:54             ` Greg KH
2018-02-13 17:25               ` Linus Torvalds
2018-02-14  8:54                 ` Greg KH
2018-02-21 10:26                   ` Lorenzo Colitti
2018-02-21 16:59                     ` Arnd Bergmann
2018-02-22 11:10                       ` Greg KH
2018-02-22 11:18                         ` Arnd Bergmann
2018-03-06 15:39                 ` Jason A. Donenfeld
2018-02-11 19:13     ` Ingo Molnar
2018-02-12 14:51       ` Joerg Roedel
2018-02-09 21:09   ` Pavel Machek
2018-02-09 21:11     ` Linus Torvalds
2018-02-09 21:28     ` Andrew Cooper
2018-02-20  3:45 David H. Gutteridge
2018-02-20  8:40 ` Joerg Roedel

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