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AFNElJ/rmS/GX9SAI8enkrm5lw9Q7KWwzSWNQeccWifhPI4VAIeGMlVm1qv4ViBSigaVdy4CuqQ=@vger.kernel.org X-Gm-Message-State: AOJu0YxwaWgPL7WMro/4FArD7IIq3VxM2qu0LTbEDA8dbI4kV96mJwsW TE1o2yqrRu12GyN99v8a5OvCKVyPfT+UvvFN3L/by6hARIsmr2WSs0beeSJtdOfusIhRyBWa/Cy RcK89SA== X-Received: from pfmy21.prod.google.com ([2002:aa7:8055:0:b0:82f:7ce1:182]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2d9a:b0:82f:aae5:c795 with SMTP id d2e1a72fcca58-834fdc9aa92mr9170785b3a.48.1777646334099; Fri, 01 May 2026 07:38:54 -0700 (PDT) Date: Fri, 1 May 2026 07:38:52 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260430150747.76749-1-pbonzini@redhat.com> <20260430150747.76749-27-pbonzini@redhat.com> Message-ID: Subject: Re: [PATCH 26/28] KVM: SVM: enable GMET and set it in MMU role From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, d.riley@proxmox.com, jon@nutanix.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Fri, May 01, 2026, Paolo Bonzini wrote: > On Thu, Apr 30, 2026 at 9:15=E2=80=AFPM Sean Christopherson wrote: > > > > On Thu, Apr 30, 2026, Paolo Bonzini wrote: > > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > > index e7fdd7a9c280..3895d8794366 100644 > > > --- a/arch/x86/kvm/svm/svm.c > > > +++ b/arch/x86/kvm/svm/svm.c > > > @@ -138,6 +138,9 @@ module_param(pause_filter_count_max, ushort, 0444= ); > > > bool __ro_after_init npt_enabled =3D true; > > > module_param_named(npt, npt_enabled, bool, 0444); > > > > > > +bool gmet_enabled =3D true; > > > > This really should be hardcoded false, with no module param, until "ena= ble GMET > > for guests". Otherwise stopping here means KVM is over-reporting suppo= rt. >=20 > Are module parameters reporting support of nested features? Not strictly speaking, no. But I do think most users, myself included, ass= ume that feature xyz is fully supported if its associated module param exist. = Though I completely agree this is an unusual case since the MBEC/GMET aren't reall= y supported for non-nested, but KVM still consumes the module param. > This is I think the only point where I disagree, I think. No worries, I'm a-ok with this one as-is. And I can see it being useful as= a bisection point.