[PATCH] arm64: KVM: Support X-Gene guest VCPU on APM X-Gene host

[Anup Patel]

Hi Marc,

On Mon, Jul 15, 2013 at 6:09 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> Hi Anup,
>
> On 15/07/13 12:46, Anup Patel wrote:
>> This patch allows us to have X-Gene guest VCPU when using
>> KVM arm64 on APM X-Gene host.
>>
>> We add KVM_ARM_TARGET_XGENE_V8 for X-Gene compatible guest VCPU
>> and we return KVM_ARM_TARGET_XGENE_V8 in kvm_target_cpu() when
>> running on X-Gene host.
>>
>> Signed-off-by: Anup Patel <anup.patel at linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar at linaro.org>
>> ---
>>  arch/arm64/include/uapi/asm/kvm.h    |    3 ++-
>>  arch/arm64/kvm/guest.c               |   34 ++++++++++++++++++++++------------
>>  arch/arm64/kvm/sys_regs_generic_v8.c |    3 +++
>>  3 files changed, 27 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index 5031f42..8194707 100644
>> --- a/arch/arm64/include/uapi/asm/kvm.h
>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>> @@ -55,8 +55,9 @@ struct kvm_regs {
>>  #define KVM_ARM_TARGET_AEM_V8                0
>>  #define KVM_ARM_TARGET_FOUNDATION_V8 1
>>  #define KVM_ARM_TARGET_CORTEX_A57    2
>> +#define KVM_ARM_TARGET_XGENE_V8              3
>>
>> -#define KVM_ARM_NUM_TARGETS          3
>> +#define KVM_ARM_NUM_TARGETS          4
>>
>>  /* KVM_ARM_SET_DEVICE_ADDR ioctl id encoding */
>>  #define KVM_ARM_DEVICE_TYPE_SHIFT    0
>> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
>> index 2c3ff67..e99b0a5 100644
>> --- a/arch/arm64/kvm/guest.c
>> +++ b/arch/arm64/kvm/guest.c
>> @@ -207,19 +207,29 @@ int __attribute_const__ kvm_target_cpu(void)
>>       unsigned long implementor = read_cpuid_implementor();
>>       unsigned long part_number = read_cpuid_part_number();
>>
>> -     if (implementor != ARM_CPU_IMP_ARM)
>> -             return -EINVAL;
>> -
>> -     switch (part_number) {
>> -     case ARM_CPU_PART_AEM_V8:
>> -             return KVM_ARM_TARGET_AEM_V8;
>> -     case ARM_CPU_PART_FOUNDATION:
>> -             return KVM_ARM_TARGET_FOUNDATION_V8;
>> -     case ARM_CPU_PART_CORTEX_A57:
>> -             /* Currently handled by the generic backend */
>> -             return KVM_ARM_TARGET_CORTEX_A57;
>> +     switch (implementor) {
>> +     case ARM_CPU_IMP_ARM:
>> +             switch (part_number) {
>> +             case ARM_CPU_PART_AEM_V8:
>> +                     return KVM_ARM_TARGET_AEM_V8;
>> +             case ARM_CPU_PART_FOUNDATION:
>> +                     return KVM_ARM_TARGET_FOUNDATION_V8;
>> +             case ARM_CPU_PART_CORTEX_A57:
>> +                     return KVM_ARM_TARGET_CORTEX_A57;
>> +             default:
>> +                     return -EINVAL;
>> +             }
>> +             break;
>> +     case ARM_CPU_IMP_APM:
>> +             switch (part_number) {
>> +             case APM_CPU_PART_POTENZA:
>> +                     return KVM_ARM_TARGET_XGENE_V8;
>
> Why don't we have KVM_ARM_TARGET_XGENE_POTENZA (or something similar)
> instead? I don't expect all the X-Gene CPUs to be the same forever...

OK, I will rename it to KVM_ARM_TARGET_XGENE_POTENZA.

Does this mean that with every new ARM64 CPU we will have to add a new
target for KVM ARM64 ?

If so then I think the list of targets will grow very fast.

I also realized that if we add a new target type in KVM ARM64 then we have
to also update KVMTOOL to use the new target else KVMTOOL fails to
recognize the target provided by KVM ARM64.

Do you think we can have KVM_ARM_TARGET_xxx to represent a common
target for a family of CPUs from given ARM64 vendor?

>
>         M.
> --
> Jazz is not dead. It just smells funny...
>
>
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Regards,
Anup