Messages in this thread | | | Date | Thu, 7 Mar 2024 11:35:00 +1300 | Subject | Re: [PATCH 11/16] KVM: x86/mmu: Explicitly disallow private accesses to emulated MMIO | From | "Huang, Kai" <> |
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On 28/02/2024 3:41 pm, Sean Christopherson wrote: > Explicitly detect and disallow private accesses to emulated MMIO in > kvm_handle_noslot_fault() instead of relying on kvm_faultin_pfn_private() > to perform the check. This will allow the page fault path to go straight > to kvm_handle_noslot_fault() without bouncing through __kvm_faultin_pfn(). > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/mmu/mmu.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 5c8caab64ba2..ebdb3fcce3dc 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3314,6 +3314,11 @@ static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, > { > gva_t gva = fault->is_tdp ? 0 : fault->addr; > > + if (fault->is_private) { > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > + return -EFAULT; > + } > +
As mentioned in another reply in this series, unless I am mistaken, for TDX guest the _first_ MMIO access would still cause EPT violation with MMIO GFN being private.
Returning to userspace cannot really help here because the MMIO mapping is inside the guest.
I am hoping I am missing something here?
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