From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Huang, Kai" <kai.huang@intel.com>
Cc: "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>,
"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
"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: Tue, 28 Aug 2018 10:01:29 +0300 [thread overview]
Message-ID: <20180828070129.GA5301@linux.intel.com> (raw)
In-Reply-To: <1535406078.3416.9.camel@intel.com>
On Mon, Aug 27, 2018 at 09:41:22PM +0000, Huang, Kai wrote:
> On Mon, 2018-08-27 at 21:53 +0300, Jarkko Sakkinen wrote:
> > From: Sean Christopherson <sean.j.christopherson@intel.com>
> >
> > Add a function to perform ENCLS(EINIT), which initializes an enclave,
> > which can be used by a driver for running enclaves and VMMs.
> >
> > Writing the LE hash MSRs is extraordinarily expensive, e.g. 3-4x
> > slower
> > than normal MSRs, so we use a per-cpu cache to track the last known
> > value
> > of the MSRs to avoid unnecessarily writing the MSRs with the current
> > value.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> > arch/x86/include/asm/sgx.h | 2 +
> > arch/x86/kernel/cpu/intel_sgx.c | 86
> > +++++++++++++++++++++++++++++++--
> > 2 files changed, 85 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> > index baf30d49b71f..c15c156436be 100644
> > --- a/arch/x86/include/asm/sgx.h
> > +++ b/arch/x86/include/asm/sgx.h
> > @@ -108,6 +108,8 @@ void sgx_free_page(struct sgx_epc_page *page);
> > void sgx_page_reclaimable(struct sgx_epc_page *page);
> > struct page *sgx_get_backing(struct file *file, pgoff_t index);
> > void sgx_put_backing(struct page *backing_page, bool write);
> > +int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken
> > *token,
> > + struct sgx_epc_page *secs_page, u64 lepubkeyhash[4]);
> >
> > #define ENCLS_FAULT_FLAG 0x40000000UL
> > #define ENCLS_FAULT_FLAG_ASM "$0x40000000"
> > diff --git a/arch/x86/kernel/cpu/intel_sgx.c
> > b/arch/x86/kernel/cpu/intel_sgx.c
> > index 1046478a3ab9..fe25e6805680 100644
> > --- a/arch/x86/kernel/cpu/intel_sgx.c
> > +++ b/arch/x86/kernel/cpu/intel_sgx.c
> > @@ -9,6 +9,7 @@
> > #include <linux/sched/signal.h>
> > #include <linux/shmem_fs.h>
> > #include <linux/slab.h>
> > +#include <linux/suspend.h>
> > #include <asm/sgx.h>
> > #include <asm/sgx_pr.h>
> >
> > @@ -38,6 +39,18 @@ static LIST_HEAD(sgx_active_page_list);
> > static DEFINE_SPINLOCK(sgx_active_page_list_lock);
> > static struct task_struct *ksgxswapd_tsk;
> > static DECLARE_WAIT_QUEUE_HEAD(ksgxswapd_waitq);
> > +static struct notifier_block sgx_pm_notifier;
> > +static u64 sgx_pm_cnt;
> > +
> > +/* The cache for the last known values of IA32_SGXLEPUBKEYHASHx MSRs
> > for each
> > + * CPU. The entries are initialized when they are first used by
> > sgx_einit().
> > + */
> > +struct sgx_lepubkeyhash {
> > + u64 msrs[4];
> > + u64 pm_cnt;
>
> May I ask why do we need pm_cnt here? In fact why do we need suspend
> staff (namely, sgx_pm_cnt above, and related code in this patch) here
> in this patch? From the patch commit message I don't see why we need PM
> staff here. Please give comment why you need PM staff, or you may
> consider to split the PM staff to another patch.
Refining the commit message probably makes more sense because without PM
code sgx_einit() would be broken. The MSRs have been reset after waking
up.
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.
This brings up one question though: how do we deal with VM host going
to sleep? VM guest would not be aware of this.
I think the best measure would be to add a new parameter to sgx_einit()
that enforces update of the MSRs. The driver can then set this parameter
in the case when sgx_einit() returns SGX_INVALID_LICENSE. This is
coherent because the driver requires writable MSRs. It would not be
coherent to do it directly in the core because KVM does not require
writable MSRs.
>
> > +};
> > +
> > +static DEFINE_PER_CPU(struct sgx_lepubkeyhash *,
> > sgx_lepubkeyhash_cache);
> >
> > /**
> > * sgx_reclaim_pages - reclaim EPC pages from the consumers
> > @@ -328,6 +341,54 @@ void sgx_put_backing(struct page *backing_page,
> > bool write)
> > }
> > EXPORT_SYMBOL_GPL(sgx_put_backing);
> >
> > +/**
> > + * sgx_einit - initialize an enclave
> > + * @sigstruct: a pointer to the SIGSTRUCT
> > + * @token: a pointer to the EINITTOKEN
> > + * @secs_page: a pointer to the SECS EPC page
> > + * @lepubkeyhash: the desired value for IA32_SGXLEPUBKEYHASHx
> > MSRs
> > + *
> > + * Try to perform EINIT operation. If the MSRs are writable, they
> > are updated
> > + * according to @lepubkeyhash.
> > + *
> > + * Return:
> > + * 0 on success,
> > + * -errno on failure
> > + * SGX error code if EINIT fails
> > + */
> > +int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken
> > *token,
> > + struct sgx_epc_page *secs_page, u64 lepubkeyhash[4])
> > +{
> > + struct sgx_lepubkeyhash __percpu *cache;
> > + bool cache_valid;
> > + int i, ret;
> > +
> > + if (!sgx_lc_enabled)
> > + return __einit(sigstruct, token,
> > sgx_epc_addr(secs_page));
> > +
> > + cache = per_cpu(sgx_lepubkeyhash_cache, smp_processor_id());
> > + if (!cache) {
> > + cache = kzalloc(sizeof(struct sgx_lepubkeyhash),
> > GFP_KERNEL);
> > + if (!cache)
> > + return -ENOMEM;
> > + }
>
> It seems per-cpu variable is a pointer to struct sgx_lepubkeyhash, and
> the actual structure is allocated at the first time the function is
> called. May I ask when will it be freed? It seems the free is not in
> this patch. Or I am misunderstanding something?
Well, it is part of the core. When the power goes of from the DRAM
banks, everything is wiped out :-)
>
> > +
> > + cache_valid = cache->pm_cnt == sgx_pm_cnt;
> > + cache->pm_cnt = sgx_pm_cnt;
> > + preempt_disable();
> > + for (i = 0; i < 4; i++) {
> > + if (cache_valid && lepubkeyhash[i] == cache-
> > >msrs[i])
> > + continue;
> > +
> > + wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i,
> > lepubkeyhash[i]);
> > + cache->msrs[i] = lepubkeyhash[i];
> > + }
> > + ret = __einit(sigstruct, token, sgx_epc_addr(secs_page));
> > + preempt_enable();
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(sgx_einit);
> > +
> > static __init int sgx_init_epc_bank(u64 addr, u64 size, unsigned
> > long index,
> > struct sgx_epc_bank *bank)
> > {
> > @@ -426,6 +487,15 @@ static __init int sgx_page_cache_init(void)
> > return 0;
> > }
> >
> > +static int sgx_pm_notifier_cb(struct notifier_block *nb, unsigned
> > long action,
> > + void *data)
> > +{
> > + if (action == PM_SUSPEND_PREPARE || action ==
> > PM_HIBERNATION_PREPARE)
> > + sgx_pm_cnt++;
> > +
> > + return NOTIFY_DONE;
> > +}
> > +
> > static __init int sgx_init(void)
> > {
> > struct task_struct *tsk;
> > @@ -452,20 +522,30 @@ static __init int sgx_init(void)
> > if (!(fc & FEATURE_CONTROL_SGX_LE_WR))
> > pr_info("IA32_SGXLEPUBKEYHASHn MSRs are not
> > writable\n");
> >
> > - ret = sgx_page_cache_init();
> > + sgx_pm_notifier.notifier_call = sgx_pm_notifier_cb;
> > + ret = register_pm_notifier(&sgx_pm_notifier);
> > if (ret)
> > return ret;
> >
> > + ret = sgx_page_cache_init();
> > + if (ret)
> > + goto out_pm;
> > +
> > tsk = kthread_run(ksgxswapd, NULL, "ksgxswapd");
> > if (IS_ERR(tsk)) {
> > - sgx_page_cache_teardown();
> > - return PTR_ERR(tsk);
> > + ret = PTR_ERR(tsk);
> > + goto out_pcache;
> > }
> > ksgxswapd_tsk = tsk;
> >
> > sgx_enabled = true;
> > sgx_lc_enabled = !!(fc & FEATURE_CONTROL_SGX_LE_WR);
> > return 0;
> > +out_pcache:
> > + sgx_page_cache_teardown();
>
> I don't think this particular 2 lines of code of 'out_pcache' case
> should be in this patch?
Yea, you are right. It cold be implemented already in the earlier patch
(note taken).
> Thanks,
> -Kai
/Jarkko
next prev parent reply other threads:[~2018-08-28 7:01 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 [this message]
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
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
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