On Thu, Feb 13, 2025, Binbin Wu wrote: > On 2/13/2025 11:23 AM, Binbin Wu wrote: > > On 2/13/2025 2:56 AM, Sean Christopherson wrote: > > > On Wed, Feb 12, 2025, Binbin Wu wrote: > > > > On 2/12/2025 8:46 AM, Sean Christopherson wrote: > > > > > I am completely comfortable saying that KVM doesn't care about STI/SS shadows > > > > > outside of the HALTED case, and so unless I'm missing something, I think it makes > > > > > sense for tdx_protected_apic_has_interrupt() to not check RVI outside of the HALTED > > > > > case, because it's impossible to know if the interrupt is actually unmasked, and > > > > > statistically it's far, far more likely that it _is_ masked. > > > > OK. Will update tdx_protected_apic_has_interrupt() in "TDX interrupts" part. > > > > And use kvm_vcpu_has_events() to replace the open code in this patch. > > > Something to keep an eye on: kvm_vcpu_has_events() returns true if pv_unhalted > > > is set, and pv_unhalted is only cleared on transitions KVM_MP_STATE_RUNNABLE. > > > If the guest initiates a spurious wakeup, pv_unhalted could be left set in > > > perpetuity. > > > > Oh, yes. > > KVM_HC_KICK_CPU is allowed in TDX guests. And a clever guest can send a REMRD IPI. > > The change below looks good to me. > > > > One minor issue is when guest initiates a spurious wakeup, pv_unhalted is > > left set, then later when the guest want to halt the vcpu, in > > __kvm_emulate_halt(), since pv_unhalted is still set and the state will not > > transit to KVM_MP_STATE_HALTED. > > But I guess it's guests' responsibility to not initiate spurious wakeup, > > guests need to bear the fact that HLT could fail due to a previous > > spurious wakeup? > > Just found a patch set for fixing the issue. FWIW, Jim's series doesn't address spurious wakeups per se, it just ensures pv_unhalted is cleared when transitioning to RUNNING. If the vCPU is already RUNNING, __apic_accept_irq() will set pv_unhalted and nothing will clear it until the next transition to RUNNING (which implies at least an attempted transition away from RUNNING).
