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When the kernel is running in a virtual machine, it cannot rely upon the

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processor family to determine if the workaround for AMD Family 10h Erratum
383 should be enabled.  To enable virtual machine migration among a
heterogeneous collection of physical machines, the hypervisor may have
been configured to report an older processor family with a reduced feature
set.  Effectively, the reported processor family and its features are like
a "least common denominator" for the collection of machines.

Therefore, when the kernel is running in a virtual machine, instead of
relying upon the processor family, we now test for features that prove
that the underlying processor is not affected by the erratum.  (The
features that we test for are unlikely to ever be emulated in software
on an affected physical processor.)

PR:		186061
Tested by:	Simon Matter
Discussed with:	jhb, neel
MFC after:	2 weeks
This commit is contained in:
Alan Cox 2014-02-22 18:53:42 +00:00
parent 324b64f7ac
commit f438547338
2 changed files with 22 additions and 10 deletions
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16
sys/amd64/amd64/pmap.c
View File

@ -1005,12 +1005,18 @@ pmap_init(void)
}
/*
* If the kernel is running in a virtual machine on an AMD Family 10h
* processor, then it must assume that MCA is enabled by the virtual
* machine monitor.
* If the kernel is running on a virtual machine, then it must assume
* that MCA is enabled by the hypervisor. Moreover, the kernel must
* be prepared for the hypervisor changing the vendor and family that
* are reported by CPUID. Consequently, the workaround for AMD Family
* 10h Erratum 383 is enabled if the processor's feature set does not
* include at least one feature that is only supported by older Intel
* or newer AMD processors.
*/
if (vm_guest == VM_GUEST_VM && cpu_vendor_id == CPU_VENDOR_AMD &&
CPUID_TO_FAMILY(cpu_id) == 0x10)
if (vm_guest == VM_GUEST_VM && (cpu_feature & CPUID_SS) == 0 &&
(cpu_feature2 & (CPUID2_SSSE3 | CPUID2_SSE41 | CPUID2_AESNI |
CPUID2_AVX | CPUID2_XSAVE)) == 0 && (amd_feature2 & (AMDID2_XOP |
AMDID2_FMA4)) == 0)
workaround_erratum383 = 1;
/*

16
sys/i386/i386/pmap.c
View File

@ -750,12 +750,18 @@ pmap_init(void)
pv_entry_high_water = 9 * (pv_entry_max / 10);
/*
* If the kernel is running in a virtual machine on an AMD Family 10h
* processor, then it must assume that MCA is enabled by the virtual
* machine monitor.
* If the kernel is running on a virtual machine, then it must assume
* that MCA is enabled by the hypervisor. Moreover, the kernel must
* be prepared for the hypervisor changing the vendor and family that
* are reported by CPUID. Consequently, the workaround for AMD Family
* 10h Erratum 383 is enabled if the processor's feature set does not
* include at least one feature that is only supported by older Intel
* or newer AMD processors.
*/
if (vm_guest == VM_GUEST_VM && cpu_vendor_id == CPU_VENDOR_AMD &&
CPUID_TO_FAMILY(cpu_id) == 0x10)
if (vm_guest == VM_GUEST_VM && (cpu_feature & CPUID_SS) == 0 &&
(cpu_feature2 & (CPUID2_SSSE3 | CPUID2_SSE41 | CPUID2_AESNI |
CPUID2_AVX | CPUID2_XSAVE)) == 0 && (amd_feature2 & (AMDID2_XOP |
AMDID2_FMA4)) == 0)
workaround_erratum383 = 1;
/*