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>,
Paolo Bonzini <pbonzini@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
Xiaoyao Li <xiaoyao.li@intel.com>,
Christopherson Sean J <sean.j.christopherson@intel.com>,
Kalle Valo <kvalo@codeaurora.org>,
Michael Chan <michael.chan@broadcom.com>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
kvm@vger.kernel.org, netdev@vger.kernel.org,
linux-wireless@vger.kernel.org
Subject: Re: [PATCH v8 13/15] x86/split_lock: Enable split lock detection by default
Date: Mon, 6 May 2019 14:39:49 -0700 [thread overview]
Message-ID: <20190506213948.GA124959@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1904250943160.1762@nanos.tec.linutronix.de>
On Thu, Apr 25, 2019 at 09:50:20AM +0200, Thomas Gleixner wrote:
> On Wed, 24 Apr 2019, Fenghua Yu wrote:
> >
> > +static void split_lock_update_msr(void)
> > +{
> > + /* Enable split lock detection */
> > + msr_set_bit(MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT);
> > + this_cpu_or(msr_test_ctl_cache, TEST_CTL_SPLIT_LOCK_DETECT);
>
> I'm pretty sure, that I told you to utilize the cache proper. Again:
>
> > > Nothing in this file initializes msr_test_ctl_cache explicitely. Register
> > > caching always requires to read the register and store it in the cache
> > > before doing anything with it. Nothing guarantees that all bits in that MSR
> > > are 0 by default forever.
> > >
> > > And once you do that _before_ calling split_lock_update_msr() then you can
> > > spare the RMW in that function.
>
> So you managed to fix the initializaiton part, but then you still do a
> pointless RMW.
Ok. I see. msr_set_bit() is a RMW operation.
So is the following the right code to update msr and cache variable?
+static void split_lock_update_msr(void)
+{
+ /* Enable split lock detection */
+ this_cpu_or(msr_test_ctl_cache, TEST_CTL_SPLIT_LOCK_DETECT);
+ wrmsrl(MSR_TEST_CTL, msr_test_ctl_cache);
Thanks.
-Fenghua
next prev parent reply other threads:[~2019-05-06 21:48 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 19:32 [PATCH v8 00/15] x86/split_lock: Enable split lock detection Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 01/15] x86/common: Align cpu_caps_cleared and cpu_caps_set to unsigned long Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 02/15] drivers/net/b44: Align pwol_mask to unsigned long for better performance Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 03/15] wlcore: simplify/fix/optimize reg_ch_conf_pending operations Fenghua Yu
2019-04-25 17:12 ` Kalle Valo
2019-04-24 19:32 ` [PATCH v8 04/15] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 05/15] x86/msr-index: Define MSR_IA32_CORE_CAPABILITY and split lock detection bit Fenghua Yu
2019-04-25 5:45 ` Ingo Molnar
2019-04-25 19:01 ` Fenghua Yu
2019-04-25 19:47 ` Ingo Molnar
2019-04-25 19:51 ` Fenghua Yu
2019-04-25 20:08 ` Ingo Molnar
2019-04-25 20:22 ` Fenghua Yu
2019-04-26 6:00 ` Ingo Molnar
2019-05-06 0:12 ` Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 06/15] x86/cpufeatures: Enumerate MSR_IA32_CORE_CAPABILITY Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 07/15] x86/split_lock: Enumerate split lock detection by MSR_IA32_CORE_CAPABILITY Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 08/15] x86/split_lock: Enumerate split lock detection on Icelake mobile processor Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 09/15] x86/split_lock: Define MSR TEST_CTL register Fenghua Yu
2019-04-25 6:21 ` Ingo Molnar
2019-04-25 19:48 ` Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 10/15] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2019-04-25 6:07 ` Ingo Molnar
2019-04-25 7:29 ` Thomas Gleixner
2019-04-24 19:32 ` [PATCH v8 11/15] kvm/x86: Emulate MSR IA32_CORE_CAPABILITY Fenghua Yu
2019-04-24 19:32 ` [PATCH v8 12/15] kvm/vmx: Emulate MSR TEST_CTL Fenghua Yu
2019-04-25 7:42 ` Thomas Gleixner
2019-04-27 12:20 ` Xiaoyao Li
2019-04-28 7:09 ` Thomas Gleixner
2019-04-28 7:34 ` Xiaoyao Li
2019-04-29 7:31 ` Thomas Gleixner
2019-04-29 5:21 ` Xiaoyao Li
2019-04-24 19:33 ` [PATCH v8 13/15] x86/split_lock: Enable split lock detection by default Fenghua Yu
2019-04-25 7:50 ` Thomas Gleixner
2019-05-06 21:39 ` Fenghua Yu [this message]
2019-04-25 10:52 ` David Laight
2019-04-25 10:58 ` Thomas Gleixner
2019-04-25 11:13 ` David Laight
2019-04-25 11:41 ` Peter Zijlstra
2019-04-25 13:04 ` Thomas Gleixner
2019-05-07 20:48 ` Fenghua Yu
2019-04-24 19:33 ` [PATCH v8 14/15] x86/split_lock: Disable split lock detection by kernel parameter "nosplit_lock_detect" Fenghua Yu
2019-04-24 19:33 ` [PATCH v8 15/15] x86/split_lock: Add a sysfs interface to enable/disable split lock detection during run time Fenghua Yu
2019-04-25 6:31 ` Ingo Molnar
2019-05-06 0:21 ` Fenghua Yu
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