Re: [Qemu-devel] CPU vendor in KVM

[李春奇]

But will the difference between the vendor ID and family number cause
confusion to the OS in VM?

On Sat, May 4, 2013 at 4:05 PM, Jan Kiszka <address@hidden> wrote:
> On 2013-05-04 09:50, 李春奇 <Arthur Chunqi Li> wrote:
>> Hi Jan and All,
>> I find that when enable KVM with qemu, vendor ID of simulated CPU will be
>> set the same as host, but other features such as level, family, model,
>> stepping are not changed. This may bring out a confusing result, the
>> simulated CPU has a vendor name of "GenuineIntel" but with family number
>> "16".
>>
>> I disabled the related code in function cpu_x86_find_by_name:
>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>> index e2302d8..df0e82e 100644
>> --- a/target-i386/cpu.c
>> +++ b/target-i386/cpu.c
>> @@ -1295,7 +1295,8 @@ static int cpu_x86_find_by_name(x86_def_t
>> *x86_cpu_def, const char *name)
>>               * KVM's sysenter/syscall emulation in compatibility mode and
>>               * when doing cross vendor migration
>>               */
>> -            if (kvm_enabled()) {
>> +            //if (kvm_enabled()) {
>> +            if (0) {
>>                  uint32_t  ebx = 0, ecx = 0, edx = 0;
>>                  host_cpuid(0, 0, NULL, &ebx, &ecx, &edx);
>>                  x86_cpu_vendor_words2str(x86_cpu_def->vendor, ebx, edx,
>> ecx);
>>
>> And the information of CPU remains consistent and the VM runs OK, even
>> though with nested environment.
>>
>> Why should qemu set simulated cpu's vendor same as the host in KVM
>> environment?
>
> The reason (and a way out) is given in the comment above the cited code.
>
> Jan
>
>



-- 
Arthur Chunqi Li
Department of Computer Science
School of EECS
Peking University
Beijing, China