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pc: Use "min-[x]level" on compat_props
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Since the automatic cpuid-level code was introduced in commit
c39c0ed ("target-i386: Automatically
set level/xlevel/xlevel2 when needed"), the CPU model tables just define
the default CPUID level code (set using "min-level").  Setting
"[x]level" forces CPUID level to a specific value and disable the
automatic-level logic.

But the PC compat code was not updated and the existing "[x]level"
compat properties broke compatibility for people using features that
triggered the auto-level code.  To keep previous behavior, we should set
"min-[x]level" instead of "[x]level" on compat_props.

This was not a problem for most cases, because old machine-types don't
have full-cpuid-auto-level enabled.  The only common use case it broke
was the CPUID[7] auto-level code, that was already enabled since the
first CPUID[7] feature was introduced (in QEMU 1.4.0).

This causes the regression reported at:
https://bugzilla.redhat.com/show_bug.cgi?id=1454641

Change the PC compat code to use "min-[x]level" instead of "[x]level" on
compat_props, and add new test cases to ensure we don't break this
again.

Reported-by: "Guo, Zhiyi" <zhguo@redhat.com>
Fixes: c39c0ed ("target-i386: Automatically set level/xlevel/xlevel2 when needed")
Cc: qemu-stable@nongnu.org
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
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ehabkost committed Jun 5, 2017
1 parent cb8b8ef commit 1f43571
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Showing 2 changed files with 59 additions and 21 deletions.
42 changes: 21 additions & 21 deletions include/hw/i386/pc.h
View file
Expand Up @@ -566,75 +566,75 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
.value = "off",\
},{\
.driver = "qemu64" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(4),\
},{\
.driver = "kvm64" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(5),\
},{\
.driver = "pentium3" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(2),\
},{\
.driver = "n270" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(5),\
},{\
.driver = "Conroe" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(4),\
},{\
.driver = "Penryn" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(4),\
},{\
.driver = "Nehalem" "-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(4),\
},{\
.driver = "n270" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Penryn" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Conroe" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Nehalem" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Westmere" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "SandyBridge" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "IvyBridge" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Haswell" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Haswell-noTSX" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Broadwell" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = "Broadwell-noTSX" "-" TYPE_X86_CPU,\
.property = "xlevel",\
.property = "min-xlevel",\
.value = stringify(0x8000000a),\
},{\
.driver = TYPE_X86_CPU,\
Expand Down Expand Up @@ -860,23 +860,23 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
.value = stringify(2),\
},{\
.driver = "Conroe-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(2),\
},{\
.driver = "Penryn-" TYPE_X86_CPU,\
.property = "model",\
.value = stringify(2),\
},{\
.driver = "Penryn-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(2),\
},{\
.driver = "Nehalem-" TYPE_X86_CPU,\
.property = "model",\
.value = stringify(2),\
},{\
.driver = "Nehalem-" TYPE_X86_CPU,\
.property = "level",\
.property = "min-level",\
.value = stringify(2),\
},{\
.driver = "virtio-net-pci",\
Expand Down
38 changes: 38 additions & 0 deletions tests/test-x86-cpuid-compat.c
View file
Expand Up @@ -313,6 +313,44 @@ int main(int argc, char **argv)
add_cpuid_test("x86/cpuid/auto-xlevel2/pc-2.7",
"-machine pc-i440fx-2.7 -cpu 486,+xstore",
"xlevel2", 0);
/*
* QEMU 1.4.0 had auto-level enabled for CPUID[7], already,
* and the compat code that sets default level shouldn't
* disable the auto-level=7 code:
*/
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-1.4/off",
"-machine pc-i440fx-1.4 -cpu Nehalem",
"level", 2);
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-1.5/on",
"-machine pc-i440fx-1.4 -cpu Nehalem,+smap",
"level", 7);
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-2.3/off",
"-machine pc-i440fx-2.3 -cpu Penryn",
"level", 4);
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-2.3/on",
"-machine pc-i440fx-2.3 -cpu Penryn,+erms",
"level", 7);
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-2.9/off",
"-machine pc-i440fx-2.9 -cpu Conroe",
"level", 10);
add_cpuid_test("x86/cpuid/auto-level7/pc-i440fx-2.9/on",
"-machine pc-i440fx-2.9 -cpu Conroe,+erms",
"level", 10);

/*
* xlevel doesn't have any feature that triggers auto-level
* code on old machine-types. Just check that the compat code
* is working correctly:
*/
add_cpuid_test("x86/cpuid/xlevel-compat/pc-i440fx-2.3",
"-machine pc-i440fx-2.3 -cpu SandyBridge",
"xlevel", 0x8000000a);
add_cpuid_test("x86/cpuid/xlevel-compat/pc-i440fx-2.4/npt-off",
"-machine pc-i440fx-2.4 -cpu SandyBridge,",
"xlevel", 0x80000008);
add_cpuid_test("x86/cpuid/xlevel-compat/pc-i440fx-2.4/npt-on",
"-machine pc-i440fx-2.4 -cpu SandyBridge,+npt",
"xlevel", 0x80000008);

/* Test feature parsing */
add_feature_test("x86/cpuid/features/plus",
Expand Down

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