Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> writes:
From: Valeriy Vdovin <valeriy.vdo...@virtuozzo.com>
Introducing new QMP command 'query-x86-cpuid'. This command can be used to
get virtualized cpu model info generated by QEMU during VM initialization in
the form of cpuid representation.
Diving into more details about virtual CPU generation: QEMU first parses '-cpu'
command line option. From there it takes the name of the model as the basis for
feature set of the new virtual CPU. After that it uses trailing '-cpu' options,
that state if additional cpu features should be present on the virtual CPU or
excluded from it (tokens '+'/'-' or '=on'/'=off').
After that QEMU checks if the host's cpu can actually support the derived
feature set and applies host limitations to it.
After this initialization procedure, virtual CPU has it's model and
vendor names, and a working feature set and is ready for identification
instructions such as CPUID.
To learn exactly how virtual CPU is presented to the guest machine via CPUID
instruction, new QMP command can be used. By calling 'query-x86-cpuid'
command, one can get a full listing of all CPUID leaves with subleaves which are
supported by the initialized virtual CPU.
Other than debug, the command is useful in cases when we would like to
utilize QEMU's virtual CPU initialization routines and put the retrieved
values into kernel CPUID overriding mechanics for more precise control
over how various processes perceive its underlying hardware with
container processes as a good example.
The command is specific to x86. It is currenly only implemented for KVM
acceleator.
Please wrap your commit messages around column 70.
Output format:
The output is a plain list of leaf/subleaf argument combinations, that
return 4 words in registers EAX, EBX, ECX, EDX.
Use example:
qmp_request: {
"execute": "x-query-x86-cpuid"
}
qmp_response: {
"return": [
{
"eax": 1073741825,
"edx": 77,
"in-eax": 1073741824,
"ecx": 1447775574,
"ebx": 1263359563
},
{
"eax": 16777339,
"edx": 0,
"in-eax": 1073741825,
"ecx": 0,
"ebx": 0
},
{
"eax": 13,
"edx": 1231384169,
"in-eax": 0,
"ecx": 1818588270,
"ebx": 1970169159
},
{
"eax": 198354,
"edx": 126614527,
"in-eax": 1,
"ecx": 2176328193,
"ebx": 2048
},
....
{
"eax": 12328,
"edx": 0,
"in-eax": 2147483656,
"ecx": 0,
"ebx": 0
}
]
}
Signed-off-by: Valeriy Vdovin <valeriy.vdo...@virtuozzo.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
This needs review from x86 CPU maintainers. Eduardo?
[...]
diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index f5ec4bc172..0ac575b1b9 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -341,3 +341,49 @@
'TARGET_I386',
'TARGET_S390X',
'TARGET_MIPS' ] } }
+
+##
+# @CpuidEntry:
+#
+# A single entry of a CPUID response.
+#
+# One entry holds full set of information (leaf) returned to the guest
+# in response to it calling a CPUID instruction with eax, ecx used as
+# the arguments to that instruction. ecx is an optional argument as
+# not all of the leaves support it.
+#
+# @in-eax: CPUID argument in eax
+# @in-ecx: CPUID argument in ecx
+# @eax: CPUID result in eax
+# @ebx: CPUID result in ebx
+# @ecx: CPUID result in ecx
+# @edx: CPUID result in edx
+#
+# Since: 7.0
+##
+{ 'struct': 'CpuidEntry',
+ 'data': { 'in-eax' : 'uint32',
+ '*in-ecx' : 'uint32',
+ 'eax' : 'uint32',
+ 'ebx' : 'uint32',
+ 'ecx' : 'uint32',
+ 'edx' : 'uint32'
+ },
+ 'if': 'TARGET_I386' }
+
+##
+# @x-query-x86-cpuid:
+#
+# Returns raw data from the emulated CPUID table for the first VCPU.
+# The emulated CPUID table defines the response to the CPUID
+# instruction when executed by the guest operating system.
+#
+#
+# Returns: a list of CpuidEntry. Returns error when qemu is configured with
+# --disable-kvm flag or if qemu is run with any other accelerator
than KVM.
Long line, please wrap around column 70.
+#
+# Since: 7.0
+##
+{ 'command': 'x-query-x86-cpuid',
+ 'returns': ['CpuidEntry'],
+ 'if': 'TARGET_I386' }
Needs feature 'unstable' now; see commit a3c45b3e62 'qapi: New special
feature flag "unstable"' and also commit 57df0dff1a "qapi: Extend
-compat to set policy for unstable interfaces". Incremental patch
appended for your convenience.
diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 0ac575b1b9..049fa48a35 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -378,6 +378,8 @@
# The emulated CPUID table defines the response to the CPUID
# instruction when executed by the guest operating system.
#
+# Features:
+# @unstable: This command is experimental.
#
# Returns: a list of CpuidEntry. Returns error when qemu is configured with
# --disable-kvm flag or if qemu is run with any other accelerator
than KVM.
@@ -386,4 +388,5 @@
##
{ 'command': 'x-query-x86-cpuid',
'returns': ['CpuidEntry'],
- 'if': 'TARGET_I386' }
+ 'if': 'TARGET_I386',
+ 'features': [ 'unstable' ] }
