Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 1 Apr 2024 12:10:58 +0800 | From | Chao Gao <> | Subject | Re: [PATCH v19 101/130] KVM: TDX: handle ept violation/misconfig exit |
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>+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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