Messages in this thread Patch in this message | | | Date | Tue, 19 Jul 2022 08:04:22 -0700 | From | Isaku Yamahata <> | Subject | Re: [PATCH v7 043/102] KVM: x86/mmu: Focibly use TDP MMU for TDX |
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On Mon, Jul 11, 2022 at 02:56:29PM +0000, Sean Christopherson <seanjc@google.com> wrote:
> s/Focibly/Forcibly, but that's a moot point because KVM shouldn't override the > the module param. KVM should instead _require_ the TDP MMU to be enabled. E.g. > if userspace disables the TDP MMU to workaround a fatal bug, then forcing the TDP > MMU may silently expose KVM to said bug. > > And overriding tdp_enabled is just mind-boggling broken, all of the SPTE masks > will be wrong. > > On Mon, Jun 27, 2022, isaku.yamahata@intel.com wrote: > > From: Isaku Yamahata <isaku.yamahata@intel.com> > > > > In this patch series, TDX supports only TDP MMU and doesn't support legacy > > MMU. Forcibly use TDP MMU for TDX irrelevant of kernel parameter to > > disable TDP MMU. > > Do not refer to the "patch series", instead phrase the statement with respect to > what KVM support. > > Require the TDP MMU for TDX guests, the so called "shadow" MMU does not > support mapping guest private memory, i.e. does not support Secure-EPT.
Thanks for rewrite of the commit message. Now the TDP MMU is default, I'll change
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> > > --- > > arch/x86/kvm/mmu/tdp_mmu.c | 9 +++++++-- > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > index 82f1bfac7ee6..7eb41b176d1e 100644 > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > @@ -18,8 +18,13 @@ int kvm_mmu_init_tdp_mmu(struct kvm *kvm) > > { > > struct workqueue_struct *wq; > > > > - if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)) > > - return 0; > > + /* > > + * Because TDX supports only TDP MMU, forcibly use TDP MMU in the case > > + * of TDX. > > + */ > > + if (kvm->arch.vm_type != KVM_X86_TDX_VM && > > + (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled))) > > + return false; > > Yeah, no. > > if (!tdp_enabled || !READ_ONCE(tdp_mmu_enabled)) > return kvm->arch.vm_type == KVM_X86_TDX_VM ? -EINVAL : 0;
I'll use -EOPNOTSUPP instead of -EINVAL. -- Isaku Yamahata <isaku.yamahata@gmail.com>
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