Date: Thu, 19 Apr 2018 00:11:02 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r332743 - in stable: 10/sys/x86/x86 11/sys/x86/x86 Message-ID: <201804190011.w3J0B22C097077@repo.freebsd.org>
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Author: jhb Date: Thu Apr 19 00:11:02 2018 New Revision: 332743 URL: https://svnweb.freebsd.org/changeset/base/332743 Log: MFC 331466: Add a workaround to the hypervisor detection for older versions of KVM. Originally KVM set %eax to 0 in the cpuid leaf 0x4000000 rather than to the highest supported leaf in the hypervisor "branch". Detect this case and fixup the %eax value so that the hypervisor is still detected. Modified: stable/10/sys/x86/x86/identcpu.c Directory Properties: stable/10/ (props changed) Changes in other areas also in this revision: Modified: stable/11/sys/x86/x86/identcpu.c Directory Properties: stable/11/ (props changed) Modified: stable/10/sys/x86/x86/identcpu.c ============================================================================== --- stable/10/sys/x86/x86/identcpu.c Wed Apr 18 23:08:10 2018 (r332742) +++ stable/10/sys/x86/x86/identcpu.c Thu Apr 19 00:11:02 2018 (r332743) @@ -1247,6 +1247,18 @@ identify_hypervisor(void) if (cpu_feature2 & CPUID2_HV) { vm_guest = VM_GUEST_VM; do_cpuid(0x40000000, regs); + + /* + * KVM from Linux kernels prior to commit + * 57c22e5f35aa4b9b2fe11f73f3e62bbf9ef36190 set %eax + * to 0 rather than a valid hv_high value. Check for + * the KVM signature bytes and fixup %eax to the + * highest supported leaf in that case. + */ + if (regs[0] == 0 && regs[1] == 0x4b4d564b && + regs[2] == 0x564b4d56 && regs[3] == 0x0000004d) + regs[0] = 0x40000001; + if (regs[0] >= 0x40000000) { hv_high = regs[0]; ((u_int *)&hv_vendor)[0] = regs[1];
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