linux-kernel - [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs

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Date:   Mon, 14 Dec 2020 11:59:52 +0800
From:   Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To:     <herbert@...dor.apana.org.au>, <davem@...emloft.net>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <x86@...nel.org>, <hpa@...or.com>, <linux-crypto@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <TimGuo-oc@...oxin.com>, <CooperYan@...oxin.com>,
        <QiyuanWang@...oxin.com>, <HerryYang@...oxin.com>,
        <CobeChen@...oxin.com>, <SilviaZhao@...oxin.com>
Subject: [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs

The driver crc32c-intel match CPUs supporting X86_FEATURE_XMM4_2.
On platforms with Zhaoxin CPUs supporting this X86 feature, when
crc32c-intel and crc32c-generic are both registered, system will
use crc32c-intel because its .cra_priority is greater than
crc32c-generic.

When doing lmbench3 Create and Delete file test on partitions with
ext4 enabling metadata checksum, found using crc32c-generic driver
could get about 20% performance gain than using the driver crc32c-intel
on some Zhaoxin CPUs.

This case expect to use crc32c-generic driver for these Zhaoxin CPUs
to get performance gain, so remove these Zhaoxin CPUs support from
crc32c-intel.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@...oxin.com>
---
 arch/x86/crypto/crc32c-intel_glue.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/crypto/crc32c-intel_glue.c b/arch/x86/crypto/crc32c-intel_glue.c
index feccb52..2cbbdde 100644
--- a/arch/x86/crypto/crc32c-intel_glue.c
+++ b/arch/x86/crypto/crc32c-intel_glue.c
@@ -215,6 +215,12 @@ static struct shash_alg alg = {
 };
 
 static const struct x86_cpu_id crc32c_cpu_id[] = {
+	X86_MATCH_VENDOR_FAM_FEATURE(ZHAOXIN, 0x6, X86_FEATURE_XMM4_2, 1),
+	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(ZHAOXIN, 0x7, 0x1b, X86_FEATURE_XMM4_2, 1),
+	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(ZHAOXIN, 0x7, 0x3b, X86_FEATURE_XMM4_2, 1),
+	X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 0x6, X86_FEATURE_XMM4_2, 1),
+	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(CENTAUR, 0x7, 0x1b, X86_FEATURE_XMM4_2, 1),
+	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(CENTAUR, 0x7, 0x3b, X86_FEATURE_XMM4_2, 1),
 	X86_MATCH_FEATURE(X86_FEATURE_XMM4_2, NULL),
 	{}
 };
@@ -222,7 +228,9 @@ MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
 
 static int __init crc32c_intel_mod_init(void)
 {
-	if (!x86_match_cpu(crc32c_cpu_id))
+	const struct x86_cpu_id *m = x86_match_cpu(crc32c_cpu_id);
+
+	if (!m || m->driver_data)
 		return -ENODEV;
 #ifdef CONFIG_X86_64
 	if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
-- 
2.7.4