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From: Jessica Yu <jeyu@kernel.org>
To: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, "Kenneth R. Crudup" <kenny@panix.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Xiaoyao Li <xiaoyao.li@intel.com>, Nadav Amit <namit@vmware.com>,
	Thomas Hellstrom <thellstrom@vmware.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect
Date: Fri, 3 Apr 2020 16:35:00 +0200	[thread overview]
Message-ID: <20200403143459.GA30424@linux-8ccs> (raw)
In-Reply-To: <bc9a0c9a-7bd0-c85d-4795-ae0b4faa5e84@prevas.dk>

+++ Rasmus Villemoes [03/04/20 01:42 +0200]:
>On 02/04/2020 14.32, Thomas Gleixner wrote:
>> From: Peter Zijlstra <peterz@infradead.org>
>>
>> It turns out that with Split-Lock-Detect enabled (default) any VMX
>> hypervisor needs at least a little modification in order to not blindly
>> inject the #AC into the guest without the guest being ready for it.
>>
>> Since there is no telling which module implements a hypervisor, scan the
>> module text and look for the VMLAUNCH instruction. If found, the module is
>> assumed to be a hypervisor of some sort and SLD is disabled.
>
>How long does that scan take/add to module load time? Would it make
>sense to exempt in-tree modules?
>
>Rasmus

I second Rasmus's question. It seems rather unfortunate that we have
to do this text scan for every module load on x86, when it doesn't
apply to the majority of them, and only to a handful of out-of-tree
hypervisor modules (assuming kvm is taken care of already).

I wonder if it would make sense then to limit the text scans to just
out-of-tree modules (i.e., missing the intree modinfo flag)?

Jessica

  reply	other threads:[~2020-04-03 14:35 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-02 12:32 [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Thomas Gleixner
2020-04-02 12:32 ` [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Thomas Gleixner
2020-04-02 15:23   ` [patch v2 " Peter Zijlstra
2020-04-02 16:20     ` Xiaoyao Li
2020-04-02 16:25       ` Peter Zijlstra
2020-04-02 16:39         ` Nadav Amit
2020-04-02 16:41         ` Xiaoyao Li
2020-04-02 17:34           ` Thomas Gleixner
2020-04-02 17:51             ` Sean Christopherson
2020-04-02 18:51               ` Peter Zijlstra
2020-04-02 20:23                 ` Sean Christopherson
2020-04-02 21:04                   ` Thomas Gleixner
2020-04-02 21:16                     ` Sean Christopherson
2020-04-03  8:09     ` David Laight
2020-04-03 14:33       ` Peter Zijlstra
2020-04-02 23:42   ` [patch " Rasmus Villemoes
2020-04-03 14:35     ` Jessica Yu [this message]
2020-04-03 15:21       ` Peter Zijlstra
2020-04-03 16:01         ` Sean Christopherson
2020-04-03 16:12           ` Peter Zijlstra
2020-04-03 16:16             ` David Laight
2020-04-03 16:39               ` Peter Zijlstra
2020-04-03 16:25             ` Sean Christopherson
2020-04-03 16:40               ` Peter Zijlstra
2020-04-03 16:48                 ` Nadav Amit
2020-04-03 17:21                   ` Sean Christopherson
2020-04-03 18:53         ` Thomas Gleixner
2020-04-03 20:58           ` Andy Lutomirski
2020-04-03 21:49             ` Thomas Gleixner
2020-04-03 11:29   ` kbuild test robot
2020-04-03 11:29     ` [patch 1/2] x86, module: " kbuild test robot
2020-04-03 14:43   ` [patch 1/2] x86,module: " kbuild test robot
2020-04-03 14:43     ` [patch 1/2] x86, module: " kbuild test robot
2020-04-03 16:36   ` [patch 1/2] x86,module: " Sean Christopherson
2020-04-03 16:41     ` Peter Zijlstra
2020-04-03 18:35       ` Jessica Yu
2020-04-06 12:23   ` Christoph Hellwig
2020-04-06 14:40     ` Peter Zijlstra
2020-04-06 15:18       ` Christoph Hellwig
2020-04-06 15:22         ` Peter Zijlstra
2020-04-06 18:27           ` Steven Rostedt
2020-04-02 12:33 ` [patch 2/2] x86/kvm/vmx: Prevent split lock detection induced #AC wreckage Thomas Gleixner
2020-04-02 15:30   ` Sean Christopherson
2020-04-02 15:44     ` Nadav Amit
2020-04-02 16:04       ` Sean Christopherson
2020-04-02 16:56     ` Thomas Gleixner
2020-04-02 15:55   ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Sean Christopherson
2020-04-02 15:55     ` [PATCH 1/3] KVM: x86: Emulate split-lock access as a write in emulator Sean Christopherson
2020-04-02 15:55     ` [PATCH 2/3] x86/split_lock: Refactor and export handle_user_split_lock() for KVM Sean Christopherson
2020-04-02 17:01       ` Thomas Gleixner
2020-04-02 17:19         ` Sean Christopherson
2020-04-02 19:06           ` Thomas Gleixner
2020-04-10  4:39             ` Xiaoyao Li
2020-04-10 10:21               ` Paolo Bonzini
2020-04-02 15:55     ` [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest Sean Christopherson
2020-04-02 17:19       ` Thomas Gleixner
2020-04-02 17:40         ` Sean Christopherson
2020-04-02 20:07           ` Thomas Gleixner
2020-04-02 20:36             ` Andy Lutomirski
2020-04-02 20:48             ` Peter Zijlstra
2020-04-02 20:51             ` Sean Christopherson
2020-04-02 22:27               ` Thomas Gleixner
2020-04-02 22:40                 ` Nadav Amit
2020-04-02 23:03                   ` Thomas Gleixner
2020-04-02 23:08                   ` Steven Rostedt
2020-04-02 23:16                     ` Kenneth R. Crudup
2020-04-02 23:18                       ` Jim Mattson
2020-04-03 12:16                         ` Thomas Gleixner
2020-04-10 10:23     ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Paolo Bonzini
2020-04-10 11:14       ` Thomas Gleixner
2020-04-02 13:43 ` [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Kenneth R. Crudup
2020-04-02 14:32   ` Peter Zijlstra
2020-04-02 14:41     ` Kenneth R. Crudup
2020-04-02 14:46       ` Peter Zijlstra
2020-04-02 14:53         ` Kenneth R. Crudup
2020-04-02 14:37   ` Thomas Gleixner
2020-04-02 14:47     ` Nadav Amit
2020-04-02 15:11       ` Peter Zijlstra
2020-04-02 14:53 [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Andy Lutomirski
2020-04-02 15:02 ` Kenneth R. Crudup
2020-04-02 16:46   ` Thomas Gleixner

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