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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