Author: avg
Date: Mon Aug 15 09:04:31 2016
New Revision: 304131
URL: https://svnweb.freebsd.org/changeset/base/304131
Log:
MFC r302835: fix-up for configuration of AMD Family 10h processors
borrowed from Linux
Modified:
stable/10/sys/amd64/amd64/initcpu.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/amd64/amd64/initcpu.c
==============================================================================
--- stable/10/sys/amd64/amd64/initcpu.c Mon Aug 15 09:04:13 2016
(r304130)
+++ stable/10/sys/amd64/amd64/initcpu.c Mon Aug 15 09:04:31 2016
(r304131)
@@ -125,6 +125,20 @@ init_amd(void)
wrmsr(MSR_NB_CFG1, msr);
}
}
+
+ /*
+ * BIOS may configure Family 10h processors to convert WC+ cache type
+ * to CD. That can hurt performance of guest VMs using nested paging.
+ * The relevant MSR bit is not documented in the BKDG,
+ * the fix is borrowed from Linux.
+ */
+ if (CPUID_TO_FAMILY(cpu_id) == 0x10) {
+ if ((cpu_feature2 & CPUID2_HV) == 0) {
+ msr = rdmsr(0xc001102a);
+ msr &= ~((uint64_t)1 << 24);
+ wrmsr(0xc001102a, msr);
+ }
+ }
}
/*
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