From: Dave Hansen <dave.hansen@intel.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Andy Lutomirski <luto@kernel.org>
Cc: "H.J. Lu" <hjl.tools@gmail.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
the arch/x86 maintainers <x86@kernel.org>,
linux-sgx@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Cedric Xing <cedric.xing@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
asapek@google.com, Borislav Petkov <bp@alien8.de>,
chenalexchen@google.com, Conrad Parker <conradparker@google.com>,
cyhanish@google.com, "Huang, Haitao" <haitao.huang@intel.com>,
Josh Triplett <josh@joshtriplett.org>,
"Huang, Kai" <kai.huang@intel.com>,
"Svahn, Kai" <kai.svahn@intel.com>, Keith Moyer <kmoy@google.com>,
Christian Ludloff <ludloff@google.com>,
Neil Horman <nhorman@redhat.com>,
Nathaniel McCallum <npmccallum@redhat.com>,
Patrick Uiterwijk <puiterwijk@redhat.com>,
David Rientjes <rientjes@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
yaozhangx@google.com, Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: Re: [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call
Date: Tue, 29 Sep 2020 07:10:30 -0700 [thread overview]
Message-ID: <f8a3826b-8e19-12a3-3280-21ba59616df8@intel.com> (raw)
In-Reply-To: <761f457d-bbb0-4b8f-e472-6705bc1d3cd1@citrix.com>
On 9/28/20 4:38 PM, Andrew Cooper wrote:
>>> CET=y, BUG_SPECTRE_V2=y: does not exist
>>> CET=n, BUG_SPECTRE_V2=y: vulnerable, use retpoline
>>> CET=y, BUG_SPECTRE_V2=n: no retpoline, not vulnerable
>>> CET=n, BUG_SPECTRE_V2=n: no retpoline, not vulnerable
>> Just to confirm: does this mean that the CPU mitigates against user
>> code mistraining the branch predictors for CPL0?
> If (and only if) you have eIBRS enabled.
>
> eIBRS should be available on all CET-capable hardware, and Linux ought
> to use it by default.
You're totally right, of course. I was (wrongly) thinking about this
VDSO retpoline as kernel code.
There's another wrinkle here. Let's say we're vulnerable to a
Spectre-v2-style attack and we want to mitigate it on CET hardware that
has enhanced IBRS. I'm not sure how reliable of a mitigation retpolines
are on enhanced IBRS hardware. Intel has recommended _against_ using
them in some cases:
> https://software.intel.com/security-software-guidance/api-app/sites/default/files/Retpoline-A-Branch-Target-Injection-Mitigation.pdf
"On processors that support enhanced IBRS, it should be used for
mitigation instead of retpoline."
I actually authored that bit of the whitepaper, and I recall that this
was not simply a recommendation based on performance advantages of using
enhanced IBRS. I can dig through some old email if we decide that we
want to explore using a retpoline on enhanced IBRS hardware.
But, let's take a step back. The changelog for this patch needs to at
least have:
1. What is the attack being mitigated by the retpoline?
2. Do we actually want to mitigate it?
3. What options are there to mitigate it?
4. Which option does this patch use and why?
Right now, there's not even a comment about this.
next prev parent reply other threads:[~2020-09-29 14:10 UTC|newest]
Thread overview: 189+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 11:28 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-09-16 11:44 ` Borislav Petkov
2020-09-16 20:30 ` Jarkko Sakkinen
2020-09-16 20:32 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Jarkko Sakkinen
2020-09-18 12:44 ` Borislav Petkov
2020-09-18 15:09 ` Andy Lutomirski
2020-09-18 15:09 ` Andy Lutomirski
2020-09-18 23:24 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect()' Jarkko Sakkinen
2020-09-18 23:53 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Sean Christopherson
2020-09-19 0:15 ` Andy Lutomirski
2020-09-22 12:58 ` Jarkko Sakkinen
2020-09-22 15:11 ` Dave Hansen
2020-09-23 13:30 ` Jarkko Sakkinen
2020-09-23 13:43 ` Jarkko Sakkinen
2020-09-23 14:33 ` Jarkko Sakkinen
2020-09-24 14:50 ` Dave Hansen
2020-09-24 16:27 ` Sean Christopherson
2020-09-24 19:35 ` Jarkko Sakkinen
2020-09-21 12:49 ` Jarkko Sakkinen
2020-09-21 12:51 ` Jarkko Sakkinen
2020-09-21 13:14 ` Jarkko Sakkinen
2020-09-21 16:57 ` Sean Christopherson
2020-09-21 21:07 ` Jarkko Sakkinen
2020-09-21 21:18 ` Sean Christopherson
2020-09-22 5:29 ` Jarkko Sakkinen
2020-09-22 5:35 ` Jarkko Sakkinen
2020-09-22 16:43 ` Sean Christopherson
2020-09-23 13:50 ` Jarkko Sakkinen
2020-09-24 19:11 ` Haitao Huang
2020-09-24 19:28 ` Sean Christopherson
2020-09-24 19:39 ` Dave Hansen
2020-09-24 20:01 ` Sean Christopherson
2020-09-24 20:10 ` Dave Hansen
2020-09-24 20:25 ` Sean Christopherson
2020-09-24 20:54 ` Dave Hansen
2020-09-24 22:10 ` Jarkko Sakkinen
2020-09-24 23:05 ` Sean Christopherson
2020-09-24 23:09 ` Dave Hansen
2020-09-25 0:00 ` Sean Christopherson
2020-09-25 17:18 ` Dave Hansen
2020-09-25 19:43 ` Sean Christopherson
2020-09-25 19:53 ` Dave Hansen
2020-09-26 4:15 ` Andy Lutomirski
2020-09-28 0:53 ` Jarkko Sakkinen
2020-09-28 14:04 ` Dave Hansen
2020-09-28 16:19 ` Jarkko Sakkinen
2020-09-28 16:48 ` Dave Hansen
2020-09-28 19:32 ` Jarkko Sakkinen
2020-09-28 19:45 ` Dave Hansen
2020-09-28 20:19 ` Jarkko Sakkinen
2020-09-29 1:37 ` Andy Lutomirski
2020-09-29 4:05 ` Jarkko Sakkinen
2020-09-29 14:24 ` Dave Hansen
2020-09-30 0:20 ` Jarkko Sakkinen
2020-09-30 14:35 ` Dave Hansen
2020-09-28 20:18 ` Jarkko Sakkinen
2020-10-18 8:49 ` Dr. Greg
2020-10-19 21:31 ` Sean Christopherson
2020-10-20 10:01 ` Dr. Greg
2020-10-20 16:40 ` Sean Christopherson
2020-10-24 14:37 ` Dr. Greg
2020-10-24 15:33 ` Andy Lutomirski
2020-10-26 10:51 ` Dr. Greg
2020-10-26 22:59 ` Andy Lutomirski
2020-10-27 0:40 ` Sean Christopherson
2020-09-24 22:07 ` Jarkko Sakkinen
2020-09-24 21:58 ` Jarkko Sakkinen
2020-09-24 21:55 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-09-21 9:30 ` Borislav Petkov
2020-09-21 12:09 ` Jarkko Sakkinen
2020-10-01 17:36 ` Sean Christopherson
2020-10-01 18:49 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-09-21 10:03 ` Borislav Petkov
2020-09-21 12:28 ` Jarkko Sakkinen
2020-09-21 13:51 ` Borislav Petkov
2020-09-21 19:29 ` Jarkko Sakkinen
2020-10-03 0:23 ` Haitao Huang
2020-10-03 3:24 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-09-21 17:35 ` Borislav Petkov
2020-09-21 18:10 ` Sean Christopherson
2020-09-21 18:27 ` Borislav Petkov
[not found] ` <20200921191658.GA24823@linux.intel.com>
2020-09-22 8:29 ` Borislav Petkov
2020-09-22 11:50 ` Jarkko Sakkinen
2020-09-22 12:56 ` Jethro Beekman
2020-09-22 14:29 ` Borislav Petkov
2020-09-23 14:47 ` Jarkko Sakkinen
2020-09-23 15:55 ` Borislav Petkov
2020-09-24 12:23 ` Jarkko Sakkinen
2020-09-22 16:29 ` Sean Christopherson
2020-09-21 19:22 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 15/24] x86/sgx: Enable provisioning for remote attestation Jarkko Sakkinen
2020-09-21 18:07 ` Borislav Petkov
2020-09-21 19:27 ` Jarkko Sakkinen
2020-09-21 19:41 ` Borislav Petkov
2020-09-21 21:26 ` Jarkko Sakkinen
2020-09-22 8:30 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-09-22 10:45 ` Borislav Petkov
2020-09-22 14:03 ` Jarkko Sakkinen
2020-09-22 14:24 ` Borislav Petkov
2020-09-23 14:52 ` Jarkko Sakkinen
2020-09-29 1:14 ` Sean Christopherson
2020-09-29 3:50 ` Jarkko Sakkinen
2020-09-29 8:35 ` Sean Christopherson
2020-09-22 16:24 ` Sean Christopherson
2020-09-22 18:02 ` Borislav Petkov
2020-09-23 15:25 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-09-22 15:44 ` Borislav Petkov
2020-09-23 13:20 ` Jarkko Sakkinen
2020-09-23 16:17 ` Borislav Petkov
2020-09-24 11:51 ` Jarkko Sakkinen
2020-09-24 15:57 ` Borislav Petkov
2020-09-24 20:38 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver' Jarkko Sakkinen
2020-09-24 20:40 ` Jarkko Sakkinen
2020-09-25 7:53 ` Borislav Petkov
2020-09-25 11:00 ` Jarkko Sakkinen
2020-09-25 7:51 ` Borislav Petkov
2020-09-25 11:21 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-09-23 22:07 ` Borislav Petkov
2020-09-24 12:09 ` Jarkko Sakkinen
2020-09-24 16:00 ` Borislav Petkov
2020-09-24 21:07 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-09-24 16:31 ` Borislav Petkov
2020-09-24 23:11 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-24 18:04 ` Borislav Petkov
2020-09-25 1:00 ` Jarkko Sakkinen
2020-09-25 8:28 ` Borislav Petkov
2020-09-27 23:37 ` Jarkko Sakkinen
2020-09-28 8:30 ` Borislav Petkov
2020-09-28 15:02 ` Jarkko Sakkinen
2020-09-25 8:39 ` Jethro Beekman
2020-09-25 11:17 ` Jarkko Sakkinen
2020-09-25 11:43 ` Jethro Beekman
[not found] ` <20200925003808.GB20333@linux.intel.com>
2020-09-25 1:04 ` Jarkko Sakkinen
2020-09-25 8:14 ` Borislav Petkov
2020-09-25 10:59 ` Jarkko Sakkinen
2020-09-28 14:36 ` Jarkko Sakkinen
2020-09-25 18:23 ` Andrew Cooper
2020-09-28 0:58 ` Jarkko Sakkinen
2020-09-28 16:44 ` Andrew Cooper
2020-09-28 18:07 ` H.J. Lu
2020-09-28 18:12 ` Andy Lutomirski
2020-09-28 18:17 ` Dave Hansen
2020-09-28 22:07 ` Jarkko Sakkinen
2020-09-28 21:56 ` Jarkko Sakkinen
2020-09-28 22:06 ` H.J. Lu
2020-09-28 22:18 ` Dave Hansen
2020-09-28 22:41 ` Andy Lutomirski
2020-09-28 23:38 ` Andrew Cooper
2020-09-29 14:10 ` Dave Hansen [this message]
2020-09-29 15:01 ` Andrew Cooper
2020-09-28 21:41 ` Jarkko Sakkinen
2020-09-28 20:42 ` Jarkko Sakkinen
2020-09-28 23:52 ` Andrew Cooper
2020-09-30 0:52 ` Jarkko Sakkinen
2020-09-28 15:43 ` Yu, Yu-cheng
2020-09-28 15:54 ` H.J. Lu
2020-09-28 16:40 ` Yu, Yu-cheng
2020-09-28 21:36 ` Jarkko Sakkinen
2020-09-28 20:56 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-09-23 13:50 ` Borislav Petkov
2020-09-24 11:28 ` Jarkko Sakkinen
2020-09-24 15:54 ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-09-25 22:37 ` Sean Christopherson
2020-09-28 0:44 ` Jarkko Sakkinen
-- strict thread matches above, loose matches on Subject: below --
2020-09-15 11:04 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-28 1:32 ` Jarkko Sakkinen
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