Date: Fri, 18 Jan 2019 23:54:51 +0000 (UTC) From: Conrad Meyer <cem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r343166 - head/sys/amd64/vmm Message-ID: <201901182354.x0INspeZ015766@repo.freebsd.org>
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Author: cem Date: Fri Jan 18 23:54:51 2019 New Revision: 343166 URL: https://svnweb.freebsd.org/changeset/base/343166 Log: vmm(4): Mask Spectre feature bits on AMD hosts For parity with Intel hosts, which already mask out the CPUID feature bits that indicate the presence of the SPEC_CTRL MSR, do the same on AMD. Eventually we may want to have a better support story for guests, but for now, limit the damage of incorrectly indicating an MSR we do not yet support. Eventually, we may want a generic CPUID override system for administrators, or for minimum supported feature set in heterogenous environments with failover. That is a much larger scope effort than this bug fix. PR: 235010 Reported by: Rys Sommefeldt <rys AT sommefeldt.com> Sponsored by: Dell EMC Isilon Modified: head/sys/amd64/vmm/x86.c Modified: head/sys/amd64/vmm/x86.c ============================================================================== --- head/sys/amd64/vmm/x86.c Fri Jan 18 23:26:31 2019 (r343165) +++ head/sys/amd64/vmm/x86.c Fri Jan 18 23:54:51 2019 (r343166) @@ -136,6 +136,14 @@ x86_emulate_cpuid(struct vm *vm, int vcpu_id, case CPUID_8000_0008: cpuid_count(*eax, *ecx, regs); if (vmm_is_amd()) { + /* + * As on Intel (0000_0007:0, EDX), mask out + * unsupported or unsafe AMD extended features + * (8000_0008 EBX). + */ + regs[1] &= (AMDFEID_CLZERO | AMDFEID_IRPERF | + AMDFEID_XSAVEERPTR); + vm_get_topology(vm, &sockets, &cores, &threads, &maxcpus); /*
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