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From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	kvm@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, konrad.wilk@oracle.com,
	jan.setjeeilers@oracle.com, liran.alon@oracle.com,
	jwadams@google.com, graf@amazon.de, rppt@linux.vnet.ibm.com,
	Paul Turner <pjt@google.com>
Subject: Re: [RFC v2 00/27] Kernel Address Space Isolation
Date: Fri, 12 Jul 2019 14:17:20 +0200	[thread overview]
Message-ID: <1f97f1d9-d209-f2ab-406d-fac765006f91@oracle.com> (raw)
In-Reply-To: <20190712114458.GU3402@hirez.programming.kicks-ass.net>


On 7/12/19 1:44 PM, Peter Zijlstra wrote:
> On Thu, Jul 11, 2019 at 04:25:12PM +0200, Alexandre Chartre wrote:
>> Kernel Address Space Isolation aims to use address spaces to isolate some
>> parts of the kernel (for example KVM) to prevent leaking sensitive data
>> between hyper-threads under speculative execution attacks. You can refer
>> to the first version of this RFC for more context:
>>
>>     https://lkml.org/lkml/2019/5/13/515
> 
> No, no, no!
> 
> That is the crux of this entire series; you're not punting on explaining
> exactly why we want to go dig through 26 patches of gunk.
> 
> You get to exactly explain what (your definition of) sensitive data is,
> and which speculative scenarios and how this approach mitigates them.
> 
> And included in that is a high level overview of the whole thing.
> 

Ok, I will rework the explanation. Sorry about that.

> On the one hand you've made this implementation for KVM, while on the
> other hand you're saying it is generic but then fail to describe any
> !KVM user.
> 
> AFAIK all speculative fails this is relevant to are now public, so
> excruciating horrible details are fine and required.

Ok.

> AFAIK2 this is all because of MDS but it also helps with v1.

Yes, mostly MDS and also L1TF.

> AFAIK3 this wants/needs to be combined with core-scheduling to be
> useful, but not a single mention of that is anywhere.

No. This is actually an alternative to core-scheduling. Eventually, ASI
will kick all sibling hyperthreads when exiting isolation and it needs to
run with the full kernel page-table (note that's currently not in these
patches).

So ASI can be seen as an optimization to disabling hyperthreading: instead
of just disabling hyperthreading you run with ASI, and when ASI can't preserve
isolation you will basically run with a single thread.

I will add all that to the explanation.

Thanks,

alex.

  reply	other threads:[~2019-07-12 12:22 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 14:25 [RFC v2 00/27] Kernel Address Space Isolation Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 01/26] mm/x86: Introduce kernel address space isolation Alexandre Chartre
2019-07-11 21:33   ` Thomas Gleixner
2019-07-12  7:43     ` Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 02/26] mm/asi: Abort isolation on interrupt, exception and context switch Alexandre Chartre
2019-07-11 20:11   ` Andi Kleen
2019-07-11 20:17     ` Mike Rapoport
2019-07-11 20:41       ` Alexandre Chartre
2019-07-12  0:05   ` Andy Lutomirski
2019-07-12  7:50     ` Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 03/26] mm/asi: Handle page fault due to address space isolation Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 04/26] mm/asi: Functions to track buffers allocated for an ASI page-table Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 05/26] mm/asi: Add ASI page-table entry offset functions Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 06/26] mm/asi: Add ASI page-table entry allocation functions Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 07/26] mm/asi: Add ASI page-table entry set functions Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 08/26] mm/asi: Functions to populate an ASI page-table from a VA range Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 09/26] mm/asi: Helper functions to map module into ASI Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 10/26] mm/asi: Keep track of VA ranges mapped in ASI page-table Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 11/26] mm/asi: Functions to clear ASI page-table entries for a VA range Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 12/26] mm/asi: Function to copy page-table entries for percpu buffer Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 13/26] mm/asi: Add asi_remap() function Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 14/26] mm/asi: Handle ASI mapped range leaks and overlaps Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 15/26] mm/asi: Initialize the ASI page-table with core mappings Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 16/26] mm/asi: Option to map current task into ASI Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 17/26] rcu: Move tree.h static forward declarations to tree.c Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 18/26] rcu: Make percpu rcu_data non-static Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 19/26] mm/asi: Add option to map RCU data Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 20/26] mm/asi: Add option to map cpu_hw_events Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 21/26] mm/asi: Make functions to read cr3/cr4 ASI aware Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 22/26] KVM: x86/asi: Introduce address_space_isolation module parameter Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 23/26] KVM: x86/asi: Introduce KVM address space isolation Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 24/26] KVM: x86/asi: Populate the KVM ASI page-table Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 25/26] KVM: x86/asi: Switch to KVM address space on entry to guest Alexandre Chartre
2019-07-11 14:25 ` [RFC v2 26/26] KVM: x86/asi: Map KVM memslots and IO buses into KVM ASI Alexandre Chartre
2019-07-11 14:40 ` [RFC v2 00/27] Kernel Address Space Isolation Alexandre Chartre
2019-07-11 22:38 ` Dave Hansen
2019-07-12  8:09   ` Alexandre Chartre
2019-07-12 13:51     ` Dave Hansen
2019-07-12 14:06       ` Alexandre Chartre
2019-07-12 15:23         ` Thomas Gleixner
2019-07-12 10:44   ` Thomas Gleixner
2019-07-12 11:56     ` Alexandre Chartre
2019-07-12 12:50       ` Peter Zijlstra
2019-07-12 13:43         ` Alexandre Chartre
2019-07-12 13:58           ` Dave Hansen
2019-07-12 14:36           ` Andy Lutomirski
2019-07-14 18:17             ` Alexander Graf
2019-07-12 13:54         ` Dave Hansen
2019-07-12 15:20           ` Peter Zijlstra
2019-07-12 15:16         ` Thomas Gleixner
2019-07-12 16:37           ` Alexandre Chartre
2019-07-12 16:45             ` Andy Lutomirski
2019-07-14 17:11               ` Mike Rapoport
2019-07-12 19:06             ` Peter Zijlstra
2019-07-14 15:06               ` Andy Lutomirski
2019-07-15 10:33                 ` Peter Zijlstra
2019-07-12 19:48             ` Thomas Gleixner
2019-07-15  8:23               ` Alexandre Chartre
2019-07-15  8:28                 ` Thomas Gleixner
2019-07-12 16:00       ` Thomas Gleixner
2019-07-12 11:44 ` Peter Zijlstra
2019-07-12 12:17   ` Alexandre Chartre [this message]
2019-07-12 12:36     ` Peter Zijlstra
2019-07-12 12:47       ` Alexandre Chartre
2019-07-12 13:07         ` Peter Zijlstra
2019-07-12 13:46           ` Alexandre Chartre
2019-07-31 16:31             ` Dario Faggioli
2019-08-22 12:31               ` Alexandre Chartre
2020-07-01 13:55 hackapple
2020-07-01 14:00 黄金海
2020-07-01 14:02 黄金海

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