From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: Dave Hansen <dave.hansen@intel.com>,
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,
peterz@infradead.org, kvm@vger.kernel.org, x86@kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
liran.alon@oracle.com, jwadams@google.com, graf@amazon.de,
rppt@linux.vnet.ibm.com
Subject: Re: [RFC v2 00/27] Kernel Address Space Isolation
Date: Fri, 12 Jul 2019 10:09:51 +0200 [thread overview]
Message-ID: <2791712a-9f7b-18bc-e686-653181461428@oracle.com> (raw)
In-Reply-To: <5cab2a0e-1034-8748-fcbe-a17cf4fa2cd4@intel.com>
On 7/12/19 12:38 AM, Dave Hansen wrote:
> On 7/11/19 7:25 AM, Alexandre Chartre wrote:
>> - Kernel code mapped to the ASI page-table has been reduced to:
>> . the entire kernel (I still need to test with only the kernel text)
>> . the cpu entry area (because we need the GDT to be mapped)
>> . the cpu ASI session (for managing ASI)
>> . the current stack
>>
>> - Optionally, an ASI can request the following kernel mapping to be added:
>> . the stack canary
>> . the cpu offsets (this_cpu_off)
>> . the current task
>> . RCU data (rcu_data)
>> . CPU HW events (cpu_hw_events).
>
> I don't see the per-cpu areas in here. But, the ASI macros in
> entry_64.S (and asi_start_abort()) use per-cpu data.
We don't map all per-cpu areas, but only the per-cpu variables we need. ASI
code uses the per-cpu cpu_asi_session variable which is mapped when an ASI
is created (see patch 15/26):
+ /*
+ * Map the percpu ASI sessions. This is used by interrupt handlers
+ * to figure out if we have entered isolation and switch back to
+ * the kernel address space.
+ */
+ err = ASI_MAP_CPUVAR(asi, cpu_asi_session);
+ if (err)
+ return err;
> Also, this stuff seems to do naughty stuff (calling C code, touching
> per-cpu data) before the PTI CR3 writes have been done. But, I don't
> see anything excluding PTI and this code from coexisting.
My understanding is that PTI CR3 writes only happens when switching to/from
userland. While ASI enter/exit/abort happens while we are already in the kernel,
so asi_start_abort() is not called when coming from userland and so not
interacting with PTI.
For example, if ASI in used during a syscall (e.g. with KVM), we have:
-> syscall
- PTI CR3 write (kernel CR3)
- syscall handler:
...
asi_enter()-> write ASI CR3
.. code run with ASI ..
asi_exit() or asi abort -> restore original CR3
...
- PTI CR3 write (userland CR3)
<- syscall
Thanks,
alex.
next prev parent reply other threads:[~2019-07-12 8:11 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 [this message]
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
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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