Messages in this thread | | | From | Paolo Bonzini <> | Subject | Re: [PATCH v13 10/12] KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & Custom MSR. | Date | Tue, 20 Apr 2021 12:49:41 +0200 |
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On 20/04/21 01:06, Sean Christopherson wrote: >> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h >> index 950afebfba88..f6bfa138874f 100644 >> --- a/arch/x86/include/uapi/asm/kvm_para.h >> +++ b/arch/x86/include/uapi/asm/kvm_para.h >> @@ -33,6 +33,7 @@ >> #define KVM_FEATURE_PV_SCHED_YIELD 13 >> #define KVM_FEATURE_ASYNC_PF_INT 14 >> #define KVM_FEATURE_MSI_EXT_DEST_ID 15 >> +#define KVM_FEATURE_SEV_LIVE_MIGRATION 16 >> >> #define KVM_HINTS_REALTIME 0 >> >> @@ -54,6 +55,7 @@ >> #define MSR_KVM_POLL_CONTROL 0x4b564d05 >> #define MSR_KVM_ASYNC_PF_INT 0x4b564d06 >> #define MSR_KVM_ASYNC_PF_ACK 0x4b564d07 >> +#define MSR_KVM_SEV_LIVE_MIGRATION 0x4b564d08 >> >> struct kvm_steal_time { >> __u64 steal; >> @@ -136,4 +138,6 @@ struct kvm_vcpu_pv_apf_data { >> #define KVM_PV_EOI_ENABLED KVM_PV_EOI_MASK >> #define KVM_PV_EOI_DISABLED 0x0 >> >> +#define KVM_SEV_LIVE_MIGRATION_ENABLED BIT_ULL(0) > > Even though the intent is to "force" userspace to intercept the MSR, I think KVM > should at least emulate the legal bits as a nop. Deferring completely to > userspace is rather bizarre as there's not really anything to justify KVM > getting involved. It would also force userspace to filter the MSR just to > support the hypercall.
I think this is the intention, the hypercall by itself cannot do much if you cannot tell userspace that it's up-to-date.
On the other hand it is kind of wrong that KVM_GET_SUPPORTED_CPUID returns the feature, but the MSR is not supported.
> Somewhat of a nit, but I think we should do something like s/ENABLED/READY,
Agreed. I'll send a patch that puts everything together.
Paolo
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