From: Ingo Molnar <mingo@kernel.org>
To: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
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 09/15] x86/split_lock: Define MSR TEST_CTL register
Date: Thu, 25 Apr 2019 08:21:26 +0200 [thread overview]
Message-ID: <20190425062126.GC40105@gmail.com> (raw)
In-Reply-To: <1556134382-58814-10-git-send-email-fenghua.yu@intel.com>
* Fenghua Yu <fenghua.yu@intel.com> wrote:
> Setting bit 29 in MSR TEST_CTL (0x33) enables split lock detection and
> clearing the bit disables split lock detection.
>
> Define the MSR and the bit. The definitions will be used in enabling or
> disabling split lock detection.
>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> ---
> arch/x86/include/asm/msr-index.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index f65ef6f783d2..296eeb761ab6 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -39,6 +39,10 @@
>
> /* Intel MSRs. Some also available on other CPUs */
>
> +#define MSR_TEST_CTL 0x00000033
> +#define TEST_CTL_SPLIT_LOCK_DETECT_SHIFT 29
> +#define TEST_CTL_SPLIT_LOCK_DETECT BIT(29)
Three problems:
- Is MSR_TEST_CTL is not really a canonical MSR name... A quick look at
msr-index reveals the prevailing nomenclature:
dagon:~/tip> git grep -h 'define MSR' arch/x86/include/asm/msr-index.h | cut -d_ -f1-2 | sort -n | uniq -c | sort -n | tail -10
8 #define MSR_K8
8 #define MSR_MTRRfix4K
12 #define MSR_CORE
13 #define MSR_IDT
14 #define MSR_K7
16 #define MSR_PKG
19 #define MSR_F15H
33 #define MSR_AMD64
83 #define MSR_P4
163 #define MSR_IA32
I.e. this shouldn't this be something like MSR_IA32_TEST_CTL - or this
the name the Intel SDM uses? (I haven't checked.)
- The canonical way to define MSR capabilities is to use the MSR's name
as a prefix. I.e.:
MSR_TEST_CTL
MSR_TEST_CTL_SPLIT_LOCK_DETECT_BIT
MSR_TEST_CTL_SPLIT_LOCK_DETECT
etc.
Instead of the random mixture of MSR_ prefixed and non-prefixed
MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT and
TEST_CTL_SPLIT_LOCK_DETECT names.
- Finally, this is not how we define bits - the _SHIFT postfix is actively
confusing as we usually denote _SHIFT values with something that is
used in a bit-shift operation, which this isn't. Instead the proper
scheme is to postfix the bit number with _BIT and the mask with _MASK,
i.e. something like:
#define MSR_TEST_CTL 0x00000033
#define MSR_TEST_CTL_SPLIT_LOCK_DETECT_BIT 29
#define MSR_TEST_CTL_SPLIT_LOCK_DETECT BIT(MSR_TEST_CTL_SPLIT_LOCK_DETECT_BIT)
Note how this cleans up actual usage:
+ msr_set_bit(MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT);
+ this_cpu_or(msr_test_ctl_cache, TEST_CTL_SPLIT_LOCK_DETECT);
- msr_set_bit(MSR_TEST_CTL, MSR_TEST_CTL_SPLIT_LOCK_DETECT_BIT);
- this_cpu_or(msr_test_ctl_cache, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
Frankly, this kind of disorganized code in a v8 submission is *really*
disappointing, it's not like it's hard to look up these patterns and
practices in existing code...
Sigh.
Thanks,
Ingo
next prev parent reply other threads:[~2019-04-25 6:21 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 [this message]
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
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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