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i386: expose "TCGTCGTCGTCG" in the 0x40000000 CPUID leaf

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Currently when running KVM, we expose "KVMKVMKVM\0\0\0" in
the 0x40000000 CPUID leaf. Other hypervisors (VMWare,
HyperV, Xen, BHyve) all do the same thing, which leaves
TCG as the odd one out.

The CPUID signature is used by software to detect which
virtual environment they are running in and (potentially)
change behaviour in certain ways. For example, systemd
supports a ConditionVirtualization= setting in unit files.
The virt-what command can also report the virt type it is
running on

Currently both these apps have to resort to custom hacks
like looking for 'fw-cfg' entry in the /proc/device-tree
file to identify TCG.

This change thus proposes a signature "TCGTCGTCGTCG" to be
reported when running under TCG.

To hide this, the -cpu option tcg-cpuid=off can be used.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20170509132736.10071-3-berrange@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Daniel P. Berrange 2017-05-09 14:27:36 +01:00 • committed by Eduardo Habkost
parent 39736e18cd
commit 1ce36bfe64
3 changed files with 34 additions and 0 deletions
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5
include/hw/i386/pc.h
View file

@ -379,6 +379,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
#define PC_COMPAT_2_8 \
HW_COMPAT_2_8 \
{\
.driver = TYPE_X86_CPU,\
.property = "tcg-cpuid",\
.value = "off",\
},\
{\
.driver = "kvmclock",\
.property = "x-mach-use-reliable-get-clock",\