From: Mike Gilbert <floppym@gentoo.org>
Date: Sat, 30 Dec 2017 17:48:20 +0000 (-0500)
Subject: basic: detect_vm_cpuid: fix hypervisor detection
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=7b0acd5d3752492b8fb182c59976fd1a0ee61031;p=elogind.git

basic: detect_vm_cpuid: fix hypervisor detection

The __get_cpuid() function only calls __cpuid() if __get_cpuid_max()
returns a value that is less than or equal to the leaf value.

In QEMU/KVM, I found that the special hypervisor leaf value (0x40000000U)
is always larger than the value retured by __get_cpuid_max().

Avoid this problem by calling the __cpuid() macro directly once we have
checked the hypervisor bit from leaf 1.

Fixes: d31b0033b7743393562a2e9d3c1e74afea981c13
---

diff --git a/src/basic/virt.c b/src/basic/virt.c
index 15dc860ad..21e11b698 100644
--- a/src/basic/virt.c
+++ b/src/basic/virt.c
@@ -79,8 +79,7 @@ static int detect_vm_cpuid(void) {
                 unsigned j;
 
                 /* There is a hypervisor, see what it is */
-                if (__get_cpuid(0x40000000U, &eax, &ebx, &ecx, &edx) == 0)
-                        return VIRTUALIZATION_NONE;
+                __cpuid(0x40000000U, eax, ebx, ecx, edx);
 
                 sig.sig32[0] = ebx;
                 sig.sig32[1] = ecx;