Re: [Qemu-devel] [PATCH 1/2] target-i386: emulate CPUID level of real hardware

[Bandan Das]

Paolo Bonzini <address@hidden> writes:

> On 18/06/2015 17:24, Radim Krčmář wrote:
>> W10 insider has a bug where it ignores CPUID level and interprets
>> CPUID.(EAX=07H, ECX=0H) incorrectly, because CPUID in fact returned
>> CPUID.(EAX=04H, ECX=0H);  this resulted in execution of unsupported
>> instructions.
>> 
>> While it's a Windows bug, there is no reason to emulate incorrect level;
>> and amend xlevel while at it.
>> 
>> I have used http://instlatx64.atw.hu/ as a source of CPUID and checked
>> that it matches Penryn Xeon X5472, Westmere Xeon W3520, SandyBridge
>> i5-2540M, and Haswell i5-4670T.
>> 
>> kvm64 and qemu64 were bumped to 0xD to avoid similar problems.
>
> This unfortunately has to be done only for new machine types.  Old types
> will remain buggy forever.

When is it recommended to add a new machine type ? And conventionally,
new changes are to be made default and compat code takes care of the older
machine types right ?

Bandan


> Paolo
>
>> Signed-off-by: Radim Krčmář <address@hidden>
>> ---
>>  target-i386/cpu.c | 37 ++++++++++++++++++-------------------
>>  1 file changed, 18 insertions(+), 19 deletions(-)
>> 
>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>> index 4e7cdaaaa57e..d392cf46f517 100644
>> --- a/target-i386/cpu.c
>> +++ b/target-i386/cpu.c
>> @@ -677,7 +677,7 @@ struct X86CPUDefinition {
>>  static X86CPUDefinition builtin_x86_defs[] = {
>>      {
>>          .name = "qemu64",
>> -        .level = 4,
>> +        .level = 0xd,
>>          .vendor = CPUID_VENDOR_AMD,
>>          .family = 6,
>>          .model = 6,
>> @@ -753,7 +753,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>      },
>>      {
>>          .name = "kvm64",
>> -        .level = 5,
>> +        .level = 0xd,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 15,
>>          .model = 6,
>> @@ -864,7 +864,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>      },
>>      {
>>          .name = "pentium3",
>> -        .level = 2,
>> +        .level = 3,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 6,
>>          .model = 7,
>> @@ -889,8 +889,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>      },
>>      {
>>          .name = "n270",
>> -        /* original is on level 10 */
>> -        .level = 5,
>> +        .level = 10,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 6,
>>          .model = 28,
>> @@ -910,12 +909,12 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT2_NX,
>>          .features[FEAT_8000_0001_ECX] =
>>              CPUID_EXT3_LAHF_LM,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel(R) Atom(TM) CPU N270   @ 1.60GHz",
>>      },
>>      {
>>          .name = "Conroe",
>> -        .level = 4,
>> +        .level = 10,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 6,
>>          .model = 15,
>> @@ -932,12 +931,12 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT2_LM | CPUID_EXT2_NX | CPUID_EXT2_SYSCALL,
>>          .features[FEAT_8000_0001_ECX] =
>>              CPUID_EXT3_LAHF_LM,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Celeron_4x0 (Conroe/Merom Class Core 2)",
>>      },
>>      {
>>          .name = "Penryn",
>> -        .level = 4,
>> +        .level = 10,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 6,
>>          .model = 23,
>> @@ -955,12 +954,12 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT2_LM | CPUID_EXT2_NX | CPUID_EXT2_SYSCALL,
>>          .features[FEAT_8000_0001_ECX] =
>>              CPUID_EXT3_LAHF_LM,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core 2 Duo P9xxx (Penryn Class Core 2)",
>>      },
>>      {
>>          .name = "Nehalem",
>> -        .level = 4,
>> +        .level = 11,
>>          .vendor = CPUID_VENDOR_INTEL,
>>          .family = 6,
>>          .model = 26,
>> @@ -978,7 +977,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT2_LM | CPUID_EXT2_SYSCALL | CPUID_EXT2_NX,
>>          .features[FEAT_8000_0001_ECX] =
>>              CPUID_EXT3_LAHF_LM,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core i7 9xx (Nehalem Class Core i7)",
>>      },
>>      {
>> @@ -1002,7 +1001,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT2_LM | CPUID_EXT2_SYSCALL | CPUID_EXT2_NX,
>>          .features[FEAT_8000_0001_ECX] =
>>              CPUID_EXT3_LAHF_LM,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Westmere E56xx/L56xx/X56xx (Nehalem-C)",
>>      },
>>      {
>> @@ -1031,7 +1030,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT3_LAHF_LM,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Xeon E312xx (Sandy Bridge)",
>>      },
>>      {
>> @@ -1063,7 +1062,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_EXT3_LAHF_LM,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Xeon E3-12xx v2 (Ivy Bridge)",
>>      },
>>      {
>> @@ -1097,7 +1096,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ERMS | CPUID_7_0_EBX_INVPCID,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core Processor (Haswell, no TSX)",
>>      },    {
>>          .name = "Haswell",
>> @@ -1131,7 +1130,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_7_0_EBX_RTM,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core Processor (Haswell)",
>>      },
>>      {
>> @@ -1167,7 +1166,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_7_0_EBX_SMAP,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core Processor (Broadwell, no TSX)",
>>      },
>>      {
>> @@ -1203,7 +1202,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>>              CPUID_7_0_EBX_SMAP,
>>          .features[FEAT_XSAVE] =
>>              CPUID_XSAVE_XSAVEOPT,
>> -        .xlevel = 0x8000000A,
>> +        .xlevel = 0x80000008,
>>          .model_id = "Intel Core Processor (Broadwell)",
>>      },
>>      {
>>