Date: Thu, 16 Mar 2017 03:21:42 +0000 (UTC) From: Peter Grehan <grehan@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r315364 - head/sys/amd64/vmm Message-ID: <201703160321.v2G3Lgkb003067@repo.freebsd.org>
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Author: grehan Date: Thu Mar 16 03:21:42 2017 New Revision: 315364 URL: https://svnweb.freebsd.org/changeset/base/315364 Log: Hide the AMD MONITORX/MWAITX capability. Otherwise, recent Linux guests will use these instructions, resulting in #UD exceptions since bhyve doesn't implement MONITOR/MWAIT exits. This fixes boot-time hangs in recent Linux guests on Ryzen CPUs (and probably Bulldozer aka AMD FX as well). Reviewed by: kib MFC after: 1 week Modified: head/sys/amd64/vmm/x86.c Modified: head/sys/amd64/vmm/x86.c ============================================================================== --- head/sys/amd64/vmm/x86.c Thu Mar 16 03:20:59 2017 (r315363) +++ head/sys/amd64/vmm/x86.c Thu Mar 16 03:21:42 2017 (r315364) @@ -176,6 +176,9 @@ x86_emulate_cpuid(struct vm *vm, int vcp /* Don't advertise the OS visible workaround feature */ regs[2] &= ~AMDID2_OSVW; + /* Hide mwaitx/monitorx capability from the guest */ + regs[2] &= ~AMDID2_MWAITX; + /* * Hide rdtscp/ia32_tsc_aux until we know how * to deal with them.
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