From: Fenghua Yu <fenghua.yu@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>,
Dave Hansen <dave.hansen@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ashok Raj <ashok.raj@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Kalle Valo <kvalo@codeaurora.org>,
Xiaoyao Li <xiaoyao.li@intel.com>,
Michael Chan <michael.chan@broadcom.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v6 13/20] x86/split_lock: Enable split lock detection by default
Date: Wed, 10 Apr 2019 05:35:46 -0700 [thread overview]
Message-ID: <20190410123546.GA214455@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1904100827530.2020@nanos.tec.linutronix.de>
On Wed, Apr 10, 2019 at 08:31:31AM +0200, Thomas Gleixner wrote:
> On Tue, 9 Apr 2019, Fenghua Yu wrote:
> > On Thu, Apr 04, 2019 at 08:07:57PM +0200, Thomas Gleixner wrote:
> > > On Wed, 3 Apr 2019, Fenghua Yu wrote:
> > > > static void early_init_intel(struct cpuinfo_x86 *c)
> > > > {
> > > > u64 misc_enable;
> > > >
> > > > + init_split_lock_detect(c);
> > >
> > > so we have in early boot:
> > >
> > > early_cpu_init()
> > > early_identify_cpu()
> > > this_cpu->c_early_init(c)
> > > early_init_intel() {
> > > init_split_lock_detect();
> > > }
> > > ....
> > > cpu_set_core_cap_bits(c)
> > > set(FEATURE_SPLIT_LOCK)
> > >
> > > I don't have to understand how init_split_lock_detect() will magically see
> > > the feature bit which gets set afterwards, right?
> >
> > early_init_intel() is called twice on the boot CPU. Besides it's called
> > in earl_cpu_init(), it's also called in:
> > identify_boot_cpu()
> > identify_cpu()
> > init_intel()
> > early_init_intel()
> > init_split_lock_detect();
> >
> > It's true that init_split_lock_detect() doesn't see the feature bit when
> > it's called for the first time in early_cpu_init(). But it sees the feature
> > bit when it's called for the second time in identify_boot_cpu().
>
> That's hideous, really.
>
> > So is init_split_lock_detect() in the right place?
>
> You're not seriously asking that?
>
> It's obviously not the right place. We are not placing calls at random
> points just because they happen to work by chance.
Is it OK to put init_split_lock_detect(c) after early_init_intel() in
init_intel()? X86_FEATURE_SPLIT_LOCK_DETECT is available now and
init_split_lock_detec() is called only once on each CPU.
@@ -746,6 +749,8 @@ static void init_intel(struct cpuinfo_x86 *c)
{
early_init_intel(c);
+ init_split_lock_detect(c);
+
intel_workarounds(c);
Thanks.
-Fenghua
next prev parent reply other threads:[~2019-04-10 12:43 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 21:21 [PATCH v6 00/20] x86/split_lock: Enable split locked accesses detection Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 01/20] x86/common: Align cpu_caps_cleared and cpu_caps_set to unsigned long Fenghua Yu
2019-04-04 14:39 ` Borislav Petkov
2019-04-04 15:54 ` Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 02/20] drivers/net/b44: Align pwol_mask to unsigned long for better performance Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 03/20] wlcore: simplify/fix/optimize reg_ch_conf_pending operations Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 04/20] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2019-04-04 14:44 ` David Laight
2019-04-04 16:24 ` David Laight
2019-04-04 16:35 ` Sean Christopherson
2019-04-04 16:52 ` Thomas Gleixner
2019-04-04 17:29 ` Paolo Bonzini
2019-04-04 18:11 ` Thomas Gleixner
2019-04-05 9:23 ` David Laight
2019-04-03 21:21 ` [PATCH v6 05/20] x86/msr-index: Define MSR_IA32_CORE_CAPABILITY and split lock detection bit Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 06/20] x86/cpufeatures: Enumerate MSR_IA32_CORE_CAPABILITY Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 07/20] x86/split_lock: Enumerate split lock detection by MSR_IA32_CORE_CAPABILITY Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 08/20] x86/split_lock: Enumerate split lock detection on Icelake mobile processor Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 09/20] x86/split_lock: Define MSR_TEST_CTL register Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 10/20] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2019-04-04 17:31 ` Thomas Gleixner
2019-04-04 22:49 ` Fenghua Yu
2019-04-03 21:21 ` [PATCH v6 11/20] kvm/x86: Emulate MSR IA32_CORE_CAPABILITY Fenghua Yu
2019-04-05 12:00 ` Thomas Gleixner
2019-04-09 6:03 ` Xiaoyao Li
2019-04-03 21:21 ` [PATCH v6 12/20] kvm/vmx: Emulate MSR TEST_CTL Fenghua Yu
2019-04-04 14:44 ` Sean Christopherson
2019-04-08 8:54 ` Xiaoyao Li
2019-04-05 12:30 ` Thomas Gleixner
2019-04-08 9:54 ` Xiaoyao Li
2019-04-08 17:48 ` Sean Christopherson
2019-04-10 5:03 ` Xiaoyao Li
2019-04-03 21:21 ` [PATCH v6 13/20] x86/split_lock: Enable split lock detection by default Fenghua Yu
2019-04-04 18:07 ` Thomas Gleixner
2019-04-04 18:14 ` Thomas Gleixner
2019-04-04 19:23 ` Fenghua Yu
2019-04-04 19:44 ` Thomas Gleixner
2019-04-10 0:02 ` Fenghua Yu
2019-04-10 6:31 ` Thomas Gleixner
2019-04-10 12:35 ` Fenghua Yu [this message]
2019-04-10 8:50 ` David Laight
2019-04-03 21:22 ` [PATCH v6 14/20] x86/split_lock: Add a sysfs interface to enable/disable split lock detection during run time Fenghua Yu
2019-04-04 19:11 ` Thomas Gleixner
2019-04-03 21:22 ` [PATCH v6 15/20] x86/split_lock: Document the new sysfs file for split lock detection Fenghua Yu
2019-04-03 21:22 ` [PATCH v6 16/20] x86/clearcpuid: Support multiple clearcpuid options Fenghua Yu
2019-04-03 21:22 ` [PATCH v6 17/20] x86/clearcpuid: Support feature flag string in kernel option clearcpuid Fenghua Yu
2019-04-03 21:22 ` [PATCH v6 18/20] x86/clearcpuid: Apply cleared feature bits that are forced set before Fenghua Yu
2019-04-03 21:22 ` [PATCH v6 19/20] x86/clearcpuid: Clear CPUID bit in CPUID faulting Fenghua Yu
2019-04-03 21:22 ` [PATCH v6 20/20] x86/clearcpuid: Change document for kernel option clearcpuid Fenghua Yu
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