crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs

zhaoxin inclusion
category: feature
CVE: NA

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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.

This patch was submitted to mainline kernel but not accepted by upstream
maintainer whose reason is "Then create a BUG flag for it,".

We think this is not a CPU bug for Zhaoxin CPUs. So should patch the
crc32c driver for Zhaoxin CPUs but not report a BUG.

Signed-off-by: leoliu-oc <[email protected]>

arch/x86/crypto/crc32c-intel_glue.c

@@ -222,8 +222,15 @@ MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
 
 static int __init crc32c_intel_mod_init(void)
 {
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
 	if (!x86_match_cpu(crc32c_cpu_id))
 		return -ENODEV;
+
+	if ((c->x86_vendor == X86_VENDOR_ZHAOXIN || c->x86_vendor == X86_VENDOR_CENTAUR) &&
+	    (c->x86 <= 7 && c->x86_model <= 59))
+		return -ENODEV;
+
 #ifdef CONFIG_X86_64
 	if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
 		alg.update = crc32c_pcl_intel_update;