From: Fenghua Yu <fenghua.yu@intel.com>
To: "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>
Cc: "linux-kernel" <linux-kernel@vger.kernel.org>,
"x86" <x86@kernel.org>,
kvm@vger.kernel.org, Fenghua Yu <fenghua.yu@intel.com>
Subject: [PATCH v4 04/17] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access
Date: Fri, 1 Mar 2019 18:44:58 -0800 [thread overview]
Message-ID: <1551494711-213533-5-git-send-email-fenghua.yu@intel.com> (raw)
In-Reply-To: <1551494711-213533-1-git-send-email-fenghua.yu@intel.com>
set_cpu_cap() calls locked BTS and clear_cpu_cap() calls locked BTR to
operate on bitmap defined in x86_capability.
Locked BTS/BTR accesses a single unsigned long location. In 64-bit mode,
the location is at:
base address of x86_capability + (bit offset in x86_capability % 64) * 8
Since base address of x86_capability may not aligned to unsigned long,
the single unsigned long location may cross two cache lines and
accessing the location by locked BTS/BTR introductions will trigger #AC.
To fix the split lock issue, align x86_capability to unsigned long so that
the location will be always within one cache line.
Changing x86_capability[]'s type to unsigned long may also fix the issue
because x86_capability[] will be naturally aligned to unsigned long. But
this needs additional code changes. So we choose the simpler solution
by enforcing alignment using __aligned(unsigned long).
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
arch/x86/include/asm/processor.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
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));
char x86_vendor_id[16];
char x86_model_id[64];
/* in KB - valid for CPUS which support this call: */
--
2.7.4
next prev parent reply other threads:[~2019-03-02 2:53 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 ` Fenghua Yu [this message]
2019-03-04 18:52 ` [PATCH v4 04/17] x86/split_lock: Align x86_capability to unsigned long to avoid split locked access Dave Hansen
2019-03-04 19:15 ` Fenghua Yu
2019-03-04 19:29 ` Dave Hansen
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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