linux-kernel - Re: [PATCH v11 1/4] arm64: KVM: export the capability to set guest SError syndrome

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Date:   Thu, 12 Apr 2018 20:55:42 +0800
From:   gengdongjiu <gengdj.1984@...il.com>
To:     James Morse <james.morse@....com>
Cc:     Dongjiu Geng <gengdongjiu@...wei.com>, linux-doc@...r.kernel.org,
        kvm@...r.kernel.org, corbet@....net, marc.zyngier@....com,
        catalin.marinas@....com, rjw@...ysocki.net, linux@...linux.org.uk,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        zhengxiang9@...wei.com, bp@...en8.de,
        linux-arm-kernel@...ts.infradead.org, huangshaoyu@...wei.com,
        devel@...ica.org, kvmarm@...ts.cs.columbia.edu,
        christoffer.dall@...aro.org, lenb@...nel.org
Subject: Re: [PATCH v11 1/4] arm64: KVM: export the capability to set guest
 SError syndrome

HI James,
  Thanks for the review.

2018-04-10 22:15 GMT+08:00, James Morse <james.morse@....com>:
> Hi Dongjiu Geng,
>
> On 09/04/18 22:36, Dongjiu Geng wrote:
>> Before user space injects a SError, it needs to know whether it can
>> specify the guest Exception Syndrome, so KVM should tell user space
>> whether it has such capability.
>
> (you could improve the commit message by briefly explaining how/why
> user-space
> would want to do this. As this is patch 1, you don't have the context of
> the
> previous patch to say that some systems can provide an ESR with
> virtual-SError)
Exactly, thanks for the good comments.

>
>
>> diff --git a/Documentation/virtual/kvm/api.txt
>> b/Documentation/virtual/kvm/api.txt
>> index fc3ae95..8a3d708 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -4415,3 +4415,14 @@ Parameters: none
>>  This capability indicates if the flic device will be able to get/set the
>>  AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute and
>> allows
>>  to discover this without having to create a flic device.
>> +
>> +8.14 KVM_CAP_ARM_SET_SERROR_ESR
>> +
>> +Architectures: arm, arm64
>> +
>> +This capability indicates that userspace can specify syndrome value
>> reported to
>
> (Nit: 'the syndrome value')
will fix it.

>
>> +guest OS when guest takes a virtual SError interrupt exception.
>
> (Nit: 'the guest')
will fix it.

>
>> +If KVM has this capability, userspace can only specify the ISS field for
>> the ESR
>> +syndrome, can not specify the EC field which is not under control by
>> KVM.
>
> (Nit: 'it can not specify...')
will fix it.

>
>> +If this virtual SError is taken to EL1 using AArch64, this value will be
>> reported
>> +into ISS filed of ESR_EL1.
>
> (Nit: 'in the ISS field')
will fix it.

>
>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index 3256b92..38c8a64 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -77,6 +77,9 @@ 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_INJECT_SERROR_ESR:
>> +		r = cpus_have_const_cap(ARM64_HAS_RAS_EXTN);
>> +		break;
>>  	case KVM_CAP_SET_GUEST_DEBUG:
>>  	case KVM_CAP_VCPU_ATTRIBUTES:
>>  		r = 1;
>
> 'dev_ioctl' feels a bit weird, but we already have cpu_has_32bit_el1() in
> here.

Yes, although the name is "dev_ioctl", it does not have relationship
with the device.
here it mainly check vcpu capability, such as PMU, 32bit EL1 etc.

>
>
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 8fb90a0..3587b33 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -934,6 +934,7 @@ struct kvm_ppc_resize_hpt {
>>  #define KVM_CAP_S390_AIS_MIGRATION 150
>>  #define KVM_CAP_PPC_GET_CPU_CHAR 151
>>  #define KVM_CAP_S390_BPB 152
>> +#define KVM_CAP_ARM_INJECT_SERROR_ESR 153
>>
>>  #ifdef KVM_CAP_IRQ_ROUTING
>
> (patch 1&2 should probably be swapped around, as on its own this does
> thing).
ok, I will do it.

>
> Reviewed-by: James Morse <james.morse@....com>
thanks this Reviewed-by

>
>
> Thanks,
>
> James
> _______________________________________________
> kvmarm mailing list
> kvmarm@...ts.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
>

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