Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE

JIRA: https://issues.redhat.com/browse/RHEL-82917

commit f3e555b
Author: Paolo Bonzini <pbonzini@redhat.com>
Date:   Mon Mar 31 17:05:50 2025 +0200

    Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE

    TSC_DEADLINE is now advertised unconditionally by KVM_GET_SUPPORTED_CPUID,
    since commit 9be4ec3 ("KVM: x86: Advertise TSC_DEADLINE_TIMER in
    KVM_GET_SUPPORTED_CPUID", 2024-12-18).  Adjust the documentation to
    reflect the new behavior.

    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    Reviewed-by: Sean Christopherson <seanjc@google.com>
    Message-ID: <20250331150550.510320-1-pbonzini@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>

Author: Maxim Levitsky

Documentation/virt/kvm/api.rst

@@ -9055,9 +9055,10 @@ the local APIC.
 
 The same is true for the ``KVM_FEATURE_PV_UNHALT`` paravirtualized feature.
 
-CPU[EAX=1]:ECX[24] (TSC_DEADLINE) is not reported by ``KVM_GET_SUPPORTED_CPUID``.
-It can be enabled if ``KVM_CAP_TSC_DEADLINE_TIMER`` is present and the kernel
-has enabled in-kernel emulation of the local APIC.
+On older versions of Linux, CPU[EAX=1]:ECX[24] (TSC_DEADLINE) is not reported by
+``KVM_GET_SUPPORTED_CPUID``, but it can be enabled if ``KVM_CAP_TSC_DEADLINE_TIMER``
+is present and the kernel has enabled in-kernel emulation of the local APIC.
+On newer versions, ``KVM_GET_SUPPORTED_CPUID`` does report the bit as available.
 
 CPU topology
 ~~~~~~~~~~~~