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    SubjectRe: [PATCH v19 101/130] KVM: TDX: handle ept violation/misconfig exit
    >+static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu)
    >+{
    >+ unsigned long exit_qual;
    >+
    >+ if (kvm_is_private_gpa(vcpu->kvm, tdexit_gpa(vcpu))) {
    >+ /*
    >+ * Always treat SEPT violations as write faults. Ignore the
    >+ * EXIT_QUALIFICATION reported by TDX-SEAM for SEPT violations.
    >+ * TD private pages are always RWX in the SEPT tables,
    >+ * i.e. they're always mapped writable. Just as importantly,
    >+ * treating SEPT violations as write faults is necessary to
    >+ * avoid COW allocations, which will cause TDAUGPAGE failures
    >+ * due to aliasing a single HPA to multiple GPAs.
    >+ */
    >+#define TDX_SEPT_VIOLATION_EXIT_QUAL EPT_VIOLATION_ACC_WRITE
    >+ exit_qual = TDX_SEPT_VIOLATION_EXIT_QUAL;
    >+ } else {
    >+ exit_qual = tdexit_exit_qual(vcpu);
    >+ if (exit_qual & EPT_VIOLATION_ACC_INSTR) {

    Unless the CPU has a bug, instruction fetch in TD from shared memory causes a
    #PF. I think you can add a comment for this.

    Maybe KVM_BUG_ON() is more appropriate as it signifies a potential bug.

    >+ pr_warn("kvm: TDX instr fetch to shared GPA = 0x%lx @ RIP = 0x%lx\n",
    >+ tdexit_gpa(vcpu), kvm_rip_read(vcpu));
    >+ vcpu->run->exit_reason = KVM_EXIT_EXCEPTION;
    >+ vcpu->run->ex.exception = PF_VECTOR;
    >+ vcpu->run->ex.error_code = exit_qual;
    >+ return 0;
    >+ }
    >+ }
    >+
    >+ trace_kvm_page_fault(vcpu, tdexit_gpa(vcpu), exit_qual);
    >+ return __vmx_handle_ept_violation(vcpu, tdexit_gpa(vcpu), exit_qual);
    >+}
    >+
    >+static int tdx_handle_ept_misconfig(struct kvm_vcpu *vcpu)
    >+{
    >+ WARN_ON_ONCE(1);
    >+
    >+ vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
    >+ vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
    >+ vcpu->run->internal.ndata = 2;
    >+ vcpu->run->internal.data[0] = EXIT_REASON_EPT_MISCONFIG;
    >+ vcpu->run->internal.data[1] = vcpu->arch.last_vmentry_cpu;
    >+
    >+ return 0;
    >+}
    >+
    > int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
    > {
    > union tdx_exit_reason exit_reason = to_tdx(vcpu)->exit_reason;
    >@@ -1345,6 +1390,10 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
    > WARN_ON_ONCE(fastpath != EXIT_FASTPATH_NONE);
    >
    > switch (exit_reason.basic) {
    >+ case EXIT_REASON_EPT_VIOLATION:
    >+ return tdx_handle_ept_violation(vcpu);
    >+ case EXIT_REASON_EPT_MISCONFIG:
    >+ return tdx_handle_ept_misconfig(vcpu);

    Handling EPT misconfiguration can be dropped because the "default" case handles
    all unexpected exits in the same way


    > case EXIT_REASON_OTHER_SMI:
    > /*
    > * If reach here, it's not a Machine Check System Management
    >--
    >2.25.1
    >
    >

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