Re: [Qemu-devel] [PATCH v6 06/16] target-i386: Use Hypervisor level in -machine pc, accel=tcg.

[Don Slutz <Don@CloudSwitch.Com>]

On 10/09/12 15:01, Marcelo Tosatti wrote:
> On Mon, Sep 24, 2012 at 10:32:08AM -0400, Don Slutz wrote:
>> Also known as Paravirtualization level.
>>
>> This change is based on:
>>
>> Microsoft Hypervisor CPUID Leaves:
>>    http://msdn.microsoft.com/en-us/library/windows/hardware/ff542428%28v=vs.85%29.aspx
>>
>> Linux kernel change starts with:
>>    http://fixunix.com/kernel/538707-use-cpuid-communicate-hypervisor.html
>> Also:
>>    http://lkml.indiana.edu/hypermail/linux/kernel/1205.0/00100.html
>>
>> VMware documention on CPUIDs (Mechanisms to determine if software is
>> running in a VMware virtual machine):
>>    http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458
>>
>> QEMU knows this as KVM_CPUID_SIGNATURE (0x40000000) in kvm on linux.
>>
>> This does not provide vendor support in tcg yet.
>>
>> Signed-off-by: Don Slutz <Don@CloudSwitch.com>
>> ---
>>   target-i386/cpu.c |   27 +++++++++++++++++++++++++++
>>   1 files changed, 27 insertions(+), 0 deletions(-)
>>
>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>> index 48bdaf9..920278b 100644
>> --- a/target-i386/cpu.c
>> +++ b/target-i386/cpu.c
>> @@ -1651,6 +1651,21 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>>                   index =  env->cpuid_xlevel;
>>               }
>>           }
>> +    } else if (index & 0x40000000) {
>> +        if (env->cpuid_hv_level_set) {
>> +            uint32_t real_level = env->cpuid_hv_level;
>> +
>> +            /* Handle Hypervisor CPUIDs */
>> +            if (real_level < 0x40000000) {
>> +                real_level = 0x40000000;
>> +            }
>> +            if (index > real_level) {
>> +                index = real_level;
>> +            }
>> +        } else {
>> +            if (index > env->cpuid_level)
>> +                index = env->cpuid_level;
>> +        }
> Whats the purpose of this checks?
They control what happens for CPUID requests outside the defined 
ranges.  Very similar to code just above this.
>
> Please provide changelogs for each patch.
In progress.
>>       } else {
>>           if (index > env->cpuid_level)
>>               index = env->cpuid_level;
>> @@ -1789,6 +1804,18 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>>               *edx = 0;
>>           }
>>           break;
>> +    case 0x40000000:
>> +        *eax = env->cpuid_hv_level;
>> +        *ebx = 0;
>> +        *ecx = 0;
>> +        *edx = 0;
>> +        break;
>> +    case 0x40000001:
>> +        *eax = env->cpuid_kvm_features;
>> +        *ebx = 0;
>> +        *ecx = 0;
>> +        *edx = 0;
>> +        break;
>>       case 0x80000000:
>>           *eax = env->cpuid_xlevel;
>>           *ebx = env->cpuid_vendor1;
>> -- 
>> 1.7.1
>>
>> --
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    -Don Slutz