[PATCH] Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE

[PATCH] Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE

[Paolo Bonzini]

TSC_DEADLINE is now advertised unconditionally by KVM_GET_SUPPORTED_CPUID,
since commit 9be4ec35d668 ("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>
---
 Documentation/virt/kvm/api.rst | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index d90ae23c0a40..732e07b44d48 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -9265,9 +9265,10 @@ 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
 ~~~~~~~~~~~~
-- 
2.49.0

Re: [PATCH] Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE

[Sean Christopherson]

On Mon, Mar 31, 2025, Paolo Bonzini wrote:
> TSC_DEADLINE is now advertised unconditionally by KVM_GET_SUPPORTED_CPUID,
> since commit 9be4ec35d668 ("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>
> ---

Sorry, at one point I even had this on my todo list for that series.

Reviewed-by: Sean Christopherson <seanjc@google.com>