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basic: detect_vm_cpuid: fix hypervisor detection

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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: d31b0033b7
This commit is contained in:
Mike Gilbert 2017-12-30 12:48:20 -05:00 committed by Lennart Poettering
parent ad552e587f
commit 8481e3e71e
1 changed files with 1 additions and 2 deletions
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3
src/basic/virt.c
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@ -78,8 +78,7 @@ 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;