Author: kib
Date: Tue Aug 7 08:36:10 2012
New Revision: 239125
URL: http://svn.freebsd.org/changeset/base/239125
Log:
Do not apply errata 721 workaround when under hypervisor, since
typical hypervisor does not implement access to the required MSR,
causing #GP on boot.
Reported and tested by: olgeni
PR: amd64/170388
MFC after: 3 days
Modified:
head/sys/amd64/amd64/initcpu.c
Modified: head/sys/amd64/amd64/initcpu.c
==============================================================================
--- head/sys/amd64/amd64/initcpu.c Tue Aug 7 07:52:25 2012
(r239124)
+++ head/sys/amd64/amd64/initcpu.c Tue Aug 7 08:36:10 2012
(r239125)
@@ -91,11 +91,17 @@ init_amd(void)
*
* http://support.amd.com/us/Processor_TechDocs/41322_10h_Rev_Gd.pdf
* http://support.amd.com/us/Processor_TechDocs/44739_12h_Rev_Gd.pdf
+ *
+ * Hypervisors do not provide access to the errata MSR,
+ * causing #GP exception on attempt to apply the errata. The
+ * MSR write shall be done on host and persist globally
+ * anyway, so do not try to do it when under virtualization.
*/
switch (CPUID_TO_FAMILY(cpu_id)) {
case 0x10:
case 0x12:
- wrmsr(0xc0011029, rdmsr(0xc0011029) | 1);
+ if ((cpu_feature2 & CPUID2_HV) == 0)
+ wrmsr(0xc0011029, rdmsr(0xc0011029) | 1);
break;
}
}
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