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KVM: nVMX: Explicitly update vPPR on successful nested VM-Enter
Always request pending event evaluation after successful nested VM-Enter if L1 has a pending IRQ, as KVM will effectively do so anyways when APICv is enabled, by way of vmx_has_apicv_interrupt(). This will allow dropping the aforementioned APICv check, and will also allow handling nested Posted Interrupt processing entirely within vmx_check_nested_events(), which is necessary to honor priority between concurrent events. Note, checking for pending IRQs has a subtle side effect, as it results in a PPR update for L1's vAPIC (PPR virtualization does happen at VM-Enter, but for nested VM-Enter that affects L2's vAPIC, not L1's vAPIC). However, KVM updates PPR _constantly_, even when PPR technically shouldn't be refreshed, e.g. kvm_vcpu_has_events() re-evaluates PPR if IRQs are unblocked, by way of the same kvm_apic_has_interrupt() check. Ditto for nested VM-Enter itself, when nested posted interrupts are enabled. Thus, trying to avoid a PPR update on VM-Enter just to be pedantically accurate is ridiculous, given the behavior elsewhere in KVM. Link: https://lore.kernel.org/kvm/20230312180048.1778187-1-jason.cj.chen@intel.com Closes: https://lore.kernel.org/all/20240920080012.74405-1-mankku@gmail.com Signed-off-by: Chao Gao <chao.gao@intel.com> Link: https://lore.kernel.org/r/20241101191447.1807602-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
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arch/x86/kvm/vmx/nested.c

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@@ -3618,7 +3618,8 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
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* effectively unblock various events, e.g. INIT/SIPI cause VM-Exit
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* unconditionally.
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*/
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if (unlikely(evaluate_pending_interrupts))
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if (unlikely(evaluate_pending_interrupts) ||
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kvm_apic_has_interrupt(vcpu))
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kvm_make_request(KVM_REQ_EVENT, vcpu);
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/*

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