From: Dave Hansen <dave.hansen@intel.com>
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>,
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>,
linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
kvm@vger.kernel.org
Subject: Re: [PATCH v4 04/17] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access
Date: Mon, 4 Mar 2019 11:29:41 -0800 [thread overview]
Message-ID: <fe9e2245-0f11-2d2a-296d-c968ab8fcf41@intel.com> (raw)
In-Reply-To: <20190304191512.GB231946@romley-ivt3.sc.intel.com>
On 3/4/19 11:15 AM, Fenghua Yu wrote:
> On Mon, Mar 04, 2019 at 10:52:19AM -0800, Dave Hansen wrote:
>> On 3/1/19 6:44 PM, Fenghua Yu wrote:
>>> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
>>> index 33051436c864..eb8ae701ef65 100644
>>> --- a/arch/x86/include/asm/processor.h
>>> +++ b/arch/x86/include/asm/processor.h
>>> @@ -93,7 +93,9 @@ struct cpuinfo_x86 {
>>> __u32 extended_cpuid_level;
>>> /* Maximum supported CPUID level, -1=no CPUID: */
>>> int cpuid_level;
>>> - __u32 x86_capability[NCAPINTS + NBUGINTS];
>>> + /* Unsigned long alignment to avoid split lock in atomic bitmap ops */
>>> + __u32 x86_capability[NCAPINTS + NBUGINTS]
>>> + __aligned(sizeof(unsigned long));
>> I think this also warrants a comment in the changelog about the
>> alignment of 'struct cpuinfo_x86'.
> How about add "Depending on the starting address where GCC generates
> for data of struct cpuinfo_x86, x86_capability[] may or may not align to
> unsigned long...."?
If that's the case, then what good is this patch? Sounds like some of
the story is missing.
You might want to dig through some of the past discussions about this.
I know this exact topic has been broached with Thomas.
next prev parent reply other threads:[~2019-03-04 19:29 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-02 2:44 [PATCH v4 00/17] x86/split_lock: Enable #AC exception for split locked accesses Fenghua Yu
2019-03-02 2:44 ` [PATCH v4 01/17] x86/common: Align cpu_caps_cleared and cpu_caps_set to unsigned long Fenghua Yu
2019-03-04 8:33 ` Paolo Bonzini
2019-03-04 10:17 ` Peter Zijlstra
2019-03-04 10:48 ` Paolo Bonzini
2019-03-04 12:44 ` Peter Zijlstra
2019-03-04 13:13 ` Paolo Bonzini
2019-03-02 2:44 ` [PATCH v4 02/17] drivers/net/b44: Align pwol_mask to unsigned long for better performance Fenghua Yu
2019-03-04 10:00 ` Peter Zijlstra
2019-03-04 14:45 ` Fenghua Yu
2019-03-04 15:27 ` Peter Zijlstra
2019-03-02 2:44 ` [PATCH v4 03/17] wlcore: Align reg_ch_conf_pending and tmp_ch_bitmap " Fenghua Yu
2019-03-04 10:11 ` Peter Zijlstra
2019-03-04 10:46 ` Paolo Bonzini
2019-03-04 12:41 ` Peter Zijlstra
2019-03-04 13:09 ` Paolo Bonzini
2019-03-04 13:30 ` Peter Zijlstra
2019-03-04 14:40 ` Fenghua Yu
2019-03-04 15:54 ` Paolo Bonzini
2019-03-02 2:44 ` [PATCH v4 04/17] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Fenghua Yu
2019-03-04 18:52 ` Dave Hansen
2019-03-04 19:15 ` Fenghua Yu
2019-03-04 19:29 ` Dave Hansen [this message]
2019-03-04 20:08 ` Peter Zijlstra
2019-03-04 20:12 ` Peter Zijlstra
2019-03-02 2:44 ` [PATCH v4 05/17] x86/cpufeatures: Enumerate IA32_CORE_CAPABILITIES MSR Fenghua Yu
2019-03-04 18:53 ` Dave Hansen
2019-03-04 18:55 ` Yu, Fenghua
2019-03-04 19:01 ` Dave Hansen
2019-03-02 2:45 ` [PATCH v4 06/17] x86/msr-index: Define IA32_CORE_CAPABILITY MSR and #AC exception for split lock bit Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 07/17] x86/split_lock: Enumerate #AC for split lock by MSR IA32_CORE_CAPABILITY Fenghua Yu
2019-03-04 18:58 ` Dave Hansen
2019-03-04 18:59 ` Fenghua Yu
2019-03-04 19:19 ` Dave Hansen
2019-03-02 2:45 ` [PATCH v4 08/17] x86/clearcpuid: Support multiple clearcpuid options Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 09/17] x86/clearcpuid: Support feature flag string in kernel option clearcpuid Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 10/17] x86/clearcpuid: Apply cleared feature bits that are forced set before Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 11/17] x86/clearcpuid: Clear CPUID bit in CPUID faulting Fenghua Yu
2019-03-04 22:04 ` kbuild test robot
2019-03-05 7:27 ` kbuild test robot
2019-03-02 2:45 ` [PATCH v4 12/17] Change document for kernel option clearcpuid Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 13/17] x86/split_lock: Handle #AC exception for split lock Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 14/17] x86/split_lock: Add a sysfs interface to allow user to enable or disable split lock detection on all CPUs during run time Fenghua Yu
2019-03-02 2:45 ` [PATCH v4 15/17] kvm: x86: Report CORE_CAPABILITY on GET_SUPPORTED_CPUID Fenghua Yu
2019-03-04 8:38 ` Paolo Bonzini
2019-03-04 10:47 ` Xiaoyao Li
2019-03-04 10:49 ` Paolo Bonzini
2019-03-04 11:10 ` Xiaoyao Li
2019-03-04 11:14 ` Paolo Bonzini
2019-03-04 11:21 ` Xiaoyao Li
2019-03-05 7:03 ` Xiaoyao Li
2019-03-02 2:45 ` [PATCH v4 16/17] kvm: x86: Add support IA32_CORE_CAPABILITY MSR Fenghua Yu
2019-03-04 8:42 ` Paolo Bonzini
2019-03-04 12:32 ` Xiaoyao Li
2019-03-08 6:10 ` Xiaoyao Li
2019-03-08 7:54 ` Paolo Bonzini
2019-03-08 8:03 ` Xiaoyao Li
2019-03-02 2:45 ` [PATCH v4 17/17] kvm: vmx: Emulate TEST_CTL MSR Fenghua Yu
2019-03-09 2:31 ` Xiaoyao Li
2019-03-11 13:31 ` Paolo Bonzini
2019-03-11 15:10 ` Xiaoyao Li
2019-03-11 15:21 ` Paolo Bonzini
2019-03-11 16:58 ` Xiaoyao Li
2019-03-04 21:55 ` [PATCH v4 00/17] x86/split_lock: Enable #AC exception for split locked accesses Konrad Rzeszutek Wilk
2019-03-05 0:06 ` Fenghua Yu
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