diff options
| author | kib <kib@FreeBSD.org> | 2012-11-09 16:00:30 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2012-11-09 16:00:30 +0000 |
| commit | 3c8fa044cf34a658663e823843f0141de113049b (patch) | |
| tree | 5331ab0a9a757655614bd39f1a1638b7431acce3 | |
| parent | 0221456a727a8389e531b9e19c3c6c15884953f8 (diff) | |
| download | FreeBSD-src-3c8fa044cf34a658663e823843f0141de113049b.zip FreeBSD-src-3c8fa044cf34a658663e823843f0141de113049b.tar.gz | |
Do not try to enable new features in the %cr4 if running under
hypervisor. Apparently, hypervisors failed to filter out 'Standard
Extended Features' report from CPUID, but deliver #gp when
corresponding bit in %cr4 is toggled.
This shall be reconsidered later, after hypervisors correct the bug.
Reported and tested by: joel
Reviewed by: avg
MFC after: 2 weeks
| -rw-r--r-- | sys/amd64/amd64/identcpu.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/sys/amd64/amd64/identcpu.c b/sys/amd64/amd64/identcpu.c index 465316a..2517498 100644 --- a/sys/amd64/amd64/identcpu.c +++ b/sys/amd64/amd64/identcpu.c @@ -481,7 +481,7 @@ SYSINIT(hook_tsc_freq, SI_SUB_CONFIGURE, SI_ORDER_ANY, hook_tsc_freq, NULL); void identify_cpu(void) { - u_int regs[4]; + u_int regs[4], cpu_stdext_disable; do_cpuid(0, regs); cpu_high = regs[0]; @@ -516,6 +516,20 @@ identify_cpu(void) if (cpu_high >= 7) { cpuid_count(7, 0, regs); cpu_stdext_feature = regs[1]; + + /* + * Some hypervisors fail to filter out unsupported + * extended features. For now, disable the + * extensions, activation of which requires setting a + * bit in CR4, and which VM monitors do not support. + */ + if (cpu_feature2 & CPUID2_HV) { + cpu_stdext_disable = CPUID_STDEXT_FSGSBASE | + CPUID_STDEXT_SMEP; + } else + cpu_stdext_disable = 0; + TUNABLE_INT_FETCH("hw.cpu_stdext_disable", &cpu_stdext_disable); + cpu_stdext_feature &= ~cpu_stdext_disable; } if (cpu_vendor_id == CPU_VENDOR_INTEL || |
