Date: Sat, 22 Feb 2014 18:53:43 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r262338 - in head/sys: amd64/amd64 i386/i386 Message-ID: <201402221853.s1MIrh5S096875@svn.freebsd.org>
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Author: alc Date: Sat Feb 22 18:53:42 2014 New Revision: 262338 URL: http://svnweb.freebsd.org/changeset/base/262338 Log: When the kernel is running in a virtual machine, it cannot rely upon the 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 Modified: head/sys/amd64/amd64/pmap.c head/sys/i386/i386/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Sat Feb 22 17:51:10 2014 (r262337) +++ head/sys/amd64/amd64/pmap.c Sat Feb 22 18:53:42 2014 (r262338) @@ -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 (vm_guest == VM_GUEST_VM && cpu_vendor_id == CPU_VENDOR_AMD && - CPUID_TO_FAMILY(cpu_id) == 0x10) + * 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_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; /* Modified: head/sys/i386/i386/pmap.c ============================================================================== --- head/sys/i386/i386/pmap.c Sat Feb 22 17:51:10 2014 (r262337) +++ head/sys/i386/i386/pmap.c Sat Feb 22 18:53:42 2014 (r262338) @@ -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 (vm_guest == VM_GUEST_VM && cpu_vendor_id == CPU_VENDOR_AMD && - CPUID_TO_FAMILY(cpu_id) == 0x10) + * 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_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; /*
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