Messages in this thread | | | Subject | Re: [RFC PATCH v2 32/69] KVM: x86: Allow host-initiated WRMSR to set X2APIC regardless of CPUID | From | Paolo Bonzini <> | Date | Tue, 6 Jul 2021 16:09:32 +0200 |
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On 03/07/21 00:04, isaku.yamahata@intel.com wrote: > Let userspace, or in the case of TDX, KVM itself, enable X2APIC even if > X2APIC is not reported as supported in the guest's CPU model. KVM > generally does not force specific ordering between ioctls(), e.g. this > forces userspace to configure CPUID before MSRs.
You already have to do this, see for example MSR_IA32_PERF_CAPABILITIES:
struct kvm_msr_entry msr_ent = {.index = msr, .data = 0};
if (!msr_info->host_initiated) return 1; if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM) && kvm_get_msr_feature(&msr_ent)) return 1; if (data & ~msr_ent.data) return 1;
Is this patch necessary? If not, I think it can be dropped.
Paolo
> And for TDX, vCPUs > will always run with X2APIC enabled, e.g. KVM will want/need to enable > X2APIC from time zero.
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