Hi peter,
Thanks for the review.
On 2018/7/18 0:36, Peter Maydell wrote:
> On 13 July 2018 at 16:47, James Morse <james.morse@xxxxxxx> wrote:
>> From: Dongjiu Geng <gengdongjiu@xxxxxxxxxx>
>>
>> For the arm64 RAS Extension, user space can inject a virtual-SError
>> with specified ESR. So user space needs to know whether KVM support
>> to inject such SError, this interface adds this query for this capability.
>>
>> KVM will check whether system support RAS Extension, if supported, KVM
>> returns true to user space, otherwise returns false.
>>
>> Signed-off-by: Dongjiu Geng <gengdongjiu@xxxxxxxxxx>
>> Reviewed-by: James Morse <james.morse@xxxxxxx>
>> Signed-off-by: James Morse <james.morse@xxxxxxx>
>> ---
>> Documentation/virtual/kvm/api.txt | 11 +++++++++++
>> arch/arm64/kvm/reset.c | 3 +++
>> include/uapi/linux/kvm.h | 1 +
>> 3 files changed, 15 insertions(+)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index e3940f8715a5..480fa64eb52a 100644
>> --- a/Documentation/virtual/kvm/api.txt
>> +++ b/Documentation/virtual/kvm/api.txt
>> @@ -4643,3 +4643,14 @@ This capability indicates that KVM supports paravirtualized Hyper-V TLB Flush
>> hypercalls:
>> HvFlushVirtualAddressSpace, HvFlushVirtualAddressSpaceEx,
>> HvFlushVirtualAddressList, HvFlushVirtualAddressListEx.
>> +
>> +8.19 KVM_CAP_ARM_SET_SERROR_ESR
>> +
>> +Architectures: arm, arm64
>> +
>> +This capability indicates that userspace can specify the syndrome value reported
>> +to the guest OS when guest takes a virtual SError interrupt exception.
>
> "the guest"
got it, thanks
>
>> +If KVM has this capability, userspace can only specify the ISS field for the ESR
>> +syndrome, it can not specify the EC field which is not under control by KVM.
>
> Full stop or semicolon, not comma.
> Not sure what the "which is not under control by KVM" part means.
>
>> +If this virtual SError is taken to EL1 using AArch64, this value will be reported
>> +in ISS filed of ESR_EL1.
>
> "the ISS field".
got it, thanks
>
> How does this capability interact with the KVM_CAP_VCPU_EVENTS
> API in patch 1? Is it saying "you can specify the ESR via
> that API", or talking about something else?
The user space will firstly check the KVM_CAP_VCPU_EVENTS through kvm_has_vcpu_events() to know whether KVM can support get/set vcpu events,
If KVM supports get/set vcpu events, it will check KVM_CAP_ARM_SET_SERROR_ESR to know whether can set guest SError ESR, as shown the user space code in [1].
[1]:
+static int kvm_put_vcpu_events(ARMCPU *cpu)
+{
+ CPUARMState *env = &cpu->env;
+ struct kvm_vcpu_events events = {};
+
+ if (!kvm_has_vcpu_events()) {
+ return 0;
+ }
+
+ memset(&events, 0, sizeof(events));
+ events.exception.serror_pending = env->serror.pending;
+
+ if (arm_feature(env, ARM_FEATURE_RAS)) {
+ events.exception.serror_has_esr = env->serror.has_esr;
+ events.exception.serror_esr = env->serror.esr;
+ }
+
+ return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_VCPU_EVENTS, &events);
+}
>
> What happens if userspace does try to specify the EC field value ?
> Is this an error, or is it ignored ?
if userspace try to specify the EC field value, KVM will return error to userspace, do not be ignored,
>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index a3db01a28062..067c6ba969bd 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:
>> case KVM_CAP_VCPU_EVENTS:
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index b6270a3b38e9..a7d9bc4e4068 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -949,6 +949,7 @@ struct kvm_ppc_resize_hpt {
>> #define KVM_CAP_GET_MSR_FEATURES 153
>> #define KVM_CAP_HYPERV_EVENTFD 154
>> #define KVM_CAP_HYPERV_TLBFLUSH 155
>> +#define KVM_CAP_ARM_INJECT_SERROR_ESR 156
>>
>> #ifdef KVM_CAP_IRQ_ROUTING
>>
>> --
>> 2.18.0
>>
>> _______________________________________________
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>> kvmarm@xxxxxxxxxxxxxxxxxxxxx
>> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
>
> thanks
> -- PMM
>
> .
>
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