From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Huang, Kai" <kai.huang@intel.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
"platform-driver-x86@vger.kernel.org"
<platform-driver-x86@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"nhorman@redhat.com" <nhorman@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"suresh.b.siddha@intel.com" <suresh.b.siddha@intel.com>,
"Ayoun, Serge" <serge.ayoun@intel.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"npmccallum@redhat.com" <npmccallum@redhat.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
"Hansen, Dave" <dave.hansen@intel.com>
Subject: Re: [PATCH v13 10/13] x86/sgx: Add sgx_einit() for initializing enclaves
Date: Fri, 31 Aug 2018 10:43:30 -0700 [thread overview]
Message-ID: <20180831174330.GA21555@linux.intel.com> (raw)
In-Reply-To: <105F7BF4D0229846AF094488D65A098935412392@PGSMSX112.gar.corp.intel.com>
On Wed, Aug 29, 2018 at 06:45:29PM -0700, Huang, Kai wrote:
> > > > > > Some kind of counter is required to keep track of the power cycle.
> > > > > > When going to sleep the sgx_pm_cnt is increased. sgx_einit()
> > > > > > compares the current value of the global count to the value in
> > > > > > the cache entry to see whether we are in a new power cycle.
> > > > >
> > > > > You mean reset to Intel default? I think we can also just reset
> > > > > the cached MSR values on each power cycle, which would be simpler,
> > IMHO?
> > > >
> > > > Refresh my brain, does hardware reset the MSRs on a transition to S3 or
> > lower?
>
> Sorry I missed this one. To be honest I don't know. I checked the SDM and all I can find is:
>
> "On reset, the default value is the digest of Intel's signing key."
I confirmed the MSRs are reset any time the EPC is lost. Not sure
what happens if the MSRs contained a non-Intel value but feature
control is locked with SGX launch control disabled. I'll post an
update when I have an answer.
> Jarkko may know.
>
> > > >
> > > > > I think we definitely need some code to handle S3-S5, but should
> > > > > be in separate patches, since I think the major impact of S3-S5 is
> > > > > entire EPC being destroyed. I think keeping pm_cnt is not
> > > > > sufficient enough to handle such case?
> > > > > >
> > > > > > This brings up one question though: how do we deal with VM host
> > > > > > going to
> > > > sleep?
> > > > > > VM guest would not be aware of this.
> > > > >
> > > > > IMO VM just gets "sudden loss of EPC" after suspend & resume in host.
> > > > > SGX driver and SDK should be able to handle "sudden loss of EPC",
> > > > > ie, co-working together to re-establish the missing enclaves.
> > > > >
> > > > > Actually supporting "sudden loss of EPC" is a requirement to
> > > > > support live migration of VM w/ SGX. Internally long time ago we
> > > > > had a discussion and the decision was we should support SGX live
> > > > > migration given
> > > > two facts:
> > > > >
> > > > > 1) losing platform-dependent is not important. For example, losing
> > > > > sealing key is not a problem, as we could get secrets provisioned
> > > > > again from remote. 2) Both windows & linux driver commit to
> > > > > support "sudden
> > > > loss of EPC".
> > > > >
> > > > > I don't think we have to support in very first upstream driver,
> > > > > but I think we need to support someday.
> > > >
> > > > Actually, we can easily support this in the driver, at least for SGX1 hardware.
> > >
> > > That's my guess too. Just want to check whether we are still on the
> > > same page :)
> > >
> > > > SGX2 isn't difficult to handle, but we've intentionally postponed
> > > > those patches until SGX1 support is in mainline[1].
> > > > Accesses to the EPC after it is lost will cause faults. Userspace EPC accesses,
> > e.g.
> > > > ERESUME, will get a SIGSEGV that the process should interpret as an
> > > > "I should restart my enclave" event. The SDK already does this. In
> > > > the driver, we just need to be aware of this potential behavior and
> > > > not freak out. Specifically, SGX_INVD needs to not WARN on faults that may
> > have been due to a the EPC being nuked.
> > > > I think we can even remove the sgx_encl_pm_notifier() code altogether.
> > >
> > > Possibly we still need to do some cleanup, ie, all structures of enclaves, upon
> > resume?
> >
> > Not for functional reasons. The driver will automatically do the cleanup via
> > SGX_INVD when it next accesses the enclave's pages and takes a fault, e.g.
> > during reclaim. Proactively reclaiming the EPC pages would probably affect
> > performance, though not necessarily in a good way. And I think it would be a
> > beneficial to get the driver out of the suspend/hibernate/resume paths, e.g.
> > zapping all enclaves could noticeably impact suspend/resume latency.
>
> Sure.
>
> Thanks,
> -Kai
>
next prev parent reply other threads:[~2018-08-31 17:43 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-27 18:53 [PATCH v13 00/13] Intel SGX1 support Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 01/13] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2018-09-03 12:56 ` Andy Shevchenko
2018-09-03 19:10 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 02/13] x86/cpufeature: Add SGX and SGX_LC CPU features Jarkko Sakkinen
2018-08-28 0:07 ` Huang, Kai
2018-08-28 7:17 ` Jarkko Sakkinen
2018-08-29 7:36 ` Huang, Kai
2018-08-31 12:19 ` Jarkko Sakkinen
2018-08-31 16:18 ` Dr. Greg
2018-08-27 18:53 ` [PATCH v13 03/13] x86/cpufeatures: Add Intel-defined SGX leaf CPUID_12_EAX Jarkko Sakkinen
2018-08-27 19:39 ` Dave Hansen
2018-08-28 7:23 ` Jarkko Sakkinen
2018-08-28 10:21 ` Borislav Petkov
2018-08-28 10:38 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 04/13] x86/sgx: Architectural structures Jarkko Sakkinen
2018-08-27 19:41 ` Dave Hansen
2018-08-28 8:08 ` Jarkko Sakkinen
2018-09-03 13:16 ` Andy Shevchenko
2018-09-03 19:17 ` Jarkko Sakkinen
2018-09-04 16:04 ` Dave Hansen
2018-09-04 16:06 ` Andy Shevchenko
2018-09-05 17:32 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 05/13] x86/msr: Add SGX definitions to msr-index.h Jarkko Sakkinen
2018-08-27 19:42 ` Dave Hansen
2018-08-28 8:11 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 06/13] x86/sgx: Detect Intel SGX Jarkko Sakkinen
2018-08-27 19:53 ` Dave Hansen
2018-08-28 8:28 ` Jarkko Sakkinen
2018-09-03 14:26 ` Andy Shevchenko
2018-09-04 9:56 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 07/13] x86/sgx: Add data structures for tracking the EPC pages Jarkko Sakkinen
2018-08-27 21:07 ` Dave Hansen
2018-08-28 10:30 ` Jarkko Sakkinen
2018-08-28 16:53 ` Dave Hansen
2018-08-28 21:34 ` Sean Christopherson
2018-08-31 11:13 ` Jarkko Sakkinen
2018-08-31 11:10 ` Jarkko Sakkinen
2018-09-03 14:41 ` Andy Shevchenko
2018-09-04 9:59 ` Jarkko Sakkinen
2018-09-04 17:49 ` Sean Christopherson
2018-09-04 18:01 ` Andy Shevchenko
2018-09-04 18:17 ` Sean Christopherson
2018-09-05 17:36 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 08/13] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2018-09-03 15:01 ` Andy Shevchenko
2018-09-04 11:09 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 09/13] x86/sgx: Enclave Page Cache (EPC) memory manager Jarkko Sakkinen
2018-08-27 21:14 ` Dave Hansen
2018-08-28 8:36 ` Jarkko Sakkinen
2018-08-27 21:15 ` Dave Hansen
2018-08-28 8:35 ` Jarkko Sakkinen
2018-08-28 14:07 ` Dave Hansen
2018-08-28 21:22 ` Sean Christopherson
2018-08-28 21:26 ` Dave Hansen
2018-08-28 21:52 ` Sean Christopherson
2018-08-31 11:22 ` Jarkko Sakkinen
2018-09-03 19:02 ` Andy Shevchenko
2018-09-04 15:38 ` Jarkko Sakkinen
2018-09-04 15:45 ` Sean Christopherson
2018-09-11 15:04 ` Sean Christopherson
2018-09-16 11:40 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 10/13] x86/sgx: Add sgx_einit() for initializing enclaves Jarkko Sakkinen
2018-08-27 21:41 ` Huang, Kai
2018-08-28 7:01 ` Jarkko Sakkinen
2018-08-29 7:33 ` Huang, Kai
2018-08-29 20:33 ` Sean Christopherson
2018-08-29 20:58 ` Huang, Kai
2018-08-29 21:09 ` Sean Christopherson
2018-08-30 1:45 ` Huang, Kai
2018-08-31 17:43 ` Sean Christopherson [this message]
2018-08-31 21:34 ` Dr. Greg
2018-09-03 19:27 ` Jarkko Sakkinen
2018-09-03 18:15 ` Jarkko Sakkinen
2018-08-31 12:17 ` Jarkko Sakkinen
2018-08-31 18:15 ` Sean Christopherson
2018-09-03 19:19 ` Jarkko Sakkinen
2018-09-03 23:45 ` Huang, Kai
2018-09-04 14:54 ` Sean Christopherson
2018-09-04 15:30 ` Jarkko Sakkinen
2018-09-04 16:35 ` Sean Christopherson
2018-09-04 22:13 ` Huang, Kai
2018-09-05 17:39 ` Jarkko Sakkinen
2018-09-04 15:26 ` Jarkko Sakkinen
2018-09-03 13:53 ` Jann Horn
2018-09-04 9:55 ` Jarkko Sakkinen
2018-09-04 16:05 ` Andy Shevchenko
2018-08-27 18:53 ` [PATCH v13 11/13] platform/x86: Intel SGX driver Jarkko Sakkinen
2018-09-04 17:59 ` Andy Shevchenko
2018-09-05 17:33 ` Jarkko Sakkinen
2018-09-05 17:36 ` Andy Shevchenko
2018-09-06 9:21 ` Jarkko Sakkinen
2018-09-06 17:35 ` Miguel Ojeda
2018-09-07 0:50 ` Joe Perches
2018-09-07 17:02 ` Sean Christopherson
2018-09-10 18:37 ` Jarkko Sakkinen
2018-09-10 21:22 ` Joe Perches
2018-09-10 18:33 ` Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 12/13] platform/x86: ptrace() support for the " Jarkko Sakkinen
2018-08-27 18:53 ` [PATCH v13 13/13] x86/sgx: Driver documentation Jarkko Sakkinen
2018-08-27 19:40 ` Randy Dunlap
2018-08-28 7:58 ` Jarkko Sakkinen
2018-08-28 8:03 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180831174330.GA21555@linux.intel.com \
--to=sean.j.christopherson@intel.com \
--cc=dave.hansen@intel.com \
--cc=hpa@zytor.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=kai.huang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sgx@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=nhorman@redhat.com \
--cc=npmccallum@redhat.com \
--cc=platform-driver-x86@vger.kernel.org \
--cc=serge.ayoun@intel.com \
--cc=suresh.b.siddha@intel.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).