KVM: TDX: Handle TDX PV HLT hypercall

Handle TDX PV HLT hypercall and the interrupt status due to it.

TDX guest status is protected, KVM can't get the interrupt status
of TDX guest and it assumes interrupt is always allowed unless TDX
guest calls TDVMCALL with HLT, which passes the interrupt blocked flag.

If the guest halted with interrupt enabled, also query pending RVI by
checking bit 0 of TD_VCPU_STATE_DETAILS_NON_ARCH field via a seamcall.

Update vt_interrupt_allowed() for TDX based on interrupt blocked flag
passed by HLT TDVMCALL.  Do not wakeup TD vCPU if interrupt is blocked
for VT-d PI.

For NMIs, KVM cannot determine the NMI blocking status for TDX guests,
so KVM always assumes NMIs are not blocked.  In the unlikely scenario
where a guest invokes the PV HLT hypercall within an NMI handler, this
could result in a spurious wakeup.  The guest should implement the PV
HLT hypercall within a loop if it truly requires no interruptions, since
NMI could be unblocked by an IRET due to an exception occurring before
the PV HLT is executed in the NMI handler.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Message-ID: <20250227012021.1778144-7-binbin.wu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

0 files changed, 0 insertions, 0 deletions