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Tue, 29 Jul 2025 15:54:49 -0700 (PDT) Date: Tue, 29 Jul 2025 15:54:48 -0700 In-Reply-To: <1d9d6e35ebf4658bbe48e6273eefff3267759519.camel@intel.com> Mime-Version: 1.0 References: <20250729193341.621487-1-seanjc@google.com> <20250729193341.621487-3-seanjc@google.com> <1d9d6e35ebf4658bbe48e6273eefff3267759519.camel@intel.com> Message-ID: Subject: Re: [PATCH 2/5] KVM: TDX: Exit with MEMORY_FAULT on unexpected pending S-EPT Violation From: Sean Christopherson To: Rick P Edgecombe Cc: "maz@kernel.org" , "pbonzini@redhat.com" , "oliver.upton@linux.dev" , Vishal Annapurve , Xiaoyao Li , "kvmarm@lists.linux.dev" , Adrian Hunter , "linux-arm-kernel@lists.infradead.org" , "kvm@vger.kernel.org" , "nik.borisov@suse.com" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250729_155451_619117_C8D5707A X-CRM114-Status: GOOD ( 16.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 29, 2025, Rick P Edgecombe wrote: > On Tue, 2025-07-29 at 12:33 -0700, Sean Christopherson wrote: > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > > index 3e0d4edee849..c2ef03f39c32 100644 > > --- a/arch/x86/kvm/vmx/tdx.c > > +++ b/arch/x86/kvm/vmx/tdx.c > > @@ -1937,10 +1937,8 @@ static int tdx_handle_ept_violation(struct kvm_v= cpu *vcpu) > > =C2=A0 > > =C2=A0 if (vt_is_tdx_private_gpa(vcpu->kvm, gpa)) { > > =C2=A0 if (tdx_is_sept_violation_unexpected_pending(vcpu)) { > > - pr_warn("Guest access before accepting 0x%llx on vCPU %d\n", > > - gpa, vcpu->vcpu_id); > > - kvm_vm_dead(vcpu->kvm); > > - return -EIO; > > + kvm_prepare_memory_fault_exit(vcpu, gpa, 0, true, false, true); > > + return -EFAULT; > > =C2=A0 } > > =C2=A0 /* > > =C2=A0 * Always treat SEPT violations as write faults.=C2=A0 Ignore t= he >=20 > The vm_dead was added because mirror EPT will KVM_BUG_ON() if there is an > attempt to set the mirror EPT entry when it is already present. And the > unaccepted memory access will trigger an EPT violation for a mirror PTE t= hat is > already set. I think this is a better solution irrespective of the vm_dea= d > changes. In that case, this change will expose KVM to the KVM_BUG_ON(), because noth= ing prevents userspace from re-running the vCPU. Which KVM_BUG_ON() exactly ge= ts hit?