[PATCH v3 1/3] arm64: kvm: support kvmtool to detect RAS extension feature

[Paolo Bonzini]

On 02/05/2017 09:56, Christoffer Dall wrote:
> Hi Dongjiu,
> 
> Please send a cover letter for patch series with more than a single
> patch.
> 
> The subject and description of these patches are also misleading.
> Hopefully this is in no way tied to kvmtool, but to userspace
> generically, for example also to be used by QEMU?

Yes, QEMU already has a similar capability on x86.

Does ARM support background scrubbing of memory to detect errors?  If
so, are there any plans to support action-optional SIGBUS on ARM?

Paolo

> On Sun, Apr 30, 2017 at 01:37:55PM +0800, Dongjiu Geng wrote:
>> Handle kvmtool's detection for RAS extension, because sometimes
>> the APP needs to know the CPU's capacity
> 
> the APP ?
> 
> the CPU's capacity?
> 
>>
>> Signed-off-by: Dongjiu Geng <gengdongjiu at huawei.com>
>> ---
>>  arch/arm64/kvm/reset.c   | 11 +++++++++++
>>  include/uapi/linux/kvm.h |  1 +
>>  2 files changed, 12 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index d9e9697..1004039 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -64,6 +64,14 @@ static bool cpu_has_32bit_el1(void)
>>  	return !!(pfr0 & 0x20);
>>  }
>>  
>> +static bool kvm_arm_support_ras_extension(void)
>> +{
>> +	u64 pfr0;
>> +
>> +	pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1);
>> +	return !!(pfr0 & 0x10000000);
>> +}
>> +
>>  /**
>>   * kvm_arch_dev_ioctl_check_extension
>>   *
>> @@ -87,6 +95,9 @@ int kvm_arch_dev_ioctl_check_extension(struct kvm *kvm, long ext)
>>  	case KVM_CAP_ARM_PMU_V3:
>>  		r = kvm_arm_support_pmu_v3();
>>  		break;
>> +	case KVM_CAP_ARM_RAS_EXTENSION:
>> +		r = kvm_arm_support_ras_extension();
>> +		break;
> 
> You need to document this capability and API in
> Documentation/virtual/kvm/api.txt and explain how this works.
> 
> 
> 
>>  	case KVM_CAP_SET_GUEST_DEBUG:
>>  	case KVM_CAP_VCPU_ATTRIBUTES:
>>  		r = 1;
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index f51d508..27fe556 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -883,6 +883,7 @@ struct kvm_ppc_resize_hpt {
>>  #define KVM_CAP_PPC_MMU_RADIX 134
>>  #define KVM_CAP_PPC_MMU_HASH_V3 135
>>  #define KVM_CAP_IMMEDIATE_EXIT 136
>> +#define KVM_CAP_ARM_RAS_EXTENSION 137
>>  
>>  #ifdef KVM_CAP_IRQ_ROUTING
>>  
>> -- 
>> 2.10.1
>>
> 
> Thanks,
> -Christoffer
>