Date: Fri, 14 Apr 2017 16:54:52 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 218662] bhyve exposes CPU feature SDBG to guests, causing guest panic on OpenBSD 6.1 Message-ID: <bug-218662-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218662 Bug ID: 218662 Summary: bhyve exposes CPU feature SDBG to guests, causing guest panic on OpenBSD 6.1 Product: Base System Version: 10.3-RELEASE Hardware: amd64 OS: Any Status: New Severity: Affects Some People Priority: --- Component: bin Assignee: freebsd-bugs@FreeBSD.org Reporter: todd.mortimer@gmail.com When attempting to create an OpenBSD 6.1 bhyve guest on 10.3-RELEASE-p18, the guest panics early in the boot process when attempting to disable the Silicon Debug feature identified by CPU feature bit SDBG. This feature bit is passed to guests if present on the host CPU. In my case, my CPU is this: CPU: Intel(R) Core(TM) i7-4790S CPU @ 3.20GHz (3192.68-MHz K8-class CPU) Origin="GenuineIntel" Id=0x306c3 Family=0x6 Model=0x3c Stepping=3 Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE> Features2=0x7ffafbff<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,SMX,EST,TM2,SSSE3,SDBG,FMA,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,TSCDLT,AESNI,XSAVE,OSXSAVE,AVX,F16C,RDRAND> AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM> AMD Features2=0x21<LAHF,ABM> Structured Extended Features=0x27ab<FSGSBASE,TSCADJ,BMI1,AVX2,SMEP,BMI2,ERMS,INVPCID,NFPUSG> XSAVE Features=0x1<XSAVEOPT> VT-x: PAT,HLT,MTF,PAUSE,EPT,UG,VPID TSC: P-state invariant, performance statistics When OpenBSD 6.1 boots under byhve, it detects the SDBG feature and attempts to disable it, resulting in a protection fault / panic. This was discussed on the OpenBSD misc list: http://marc.info/?l=openbsd-misc&m=149136052120277&w=4 And a patch for HardenedBSD is here: https://github.com/HardenedBSD/hardenedBSD/commit/cc91b57f4d1dabddfbf8b1e7655 As a workaround, passing -w to byhve allows the guest to boot, but the CPU feature should be masked out by the host. -- You are receiving this mail because: You are the assignee for the bug.
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