KVM: PPC: Book3S HV: Fix incorrect userspace exit on ioeventfd write
When the guest does an MMIO write which is handled successfully by an ioeventfd, ioeventfd_write() returns 0 (success) and kvmppc_handle_store() returns EMULATE_DONE. Then kvmppc_emulate_mmio() converts EMULATE_DONE to RESUME_GUEST_NV and this causes an exit from the loop in kvmppc_vcpu_run_hv(), causing an exit back to userspace with a bogus exit reason code, typically causing userspace (e.g. qemu) to crash with a message about an unknown exit code. This adds handling of RESUME_GUEST_NV in kvmppc_vcpu_run_hv() in order to fix that. For generality, we define a helper to check for either of the return-to-guest codes we use, RESUME_GUEST and RESUME_GUEST_NV, to make it easy to check for either and provide one place to update if any other return-to-guest code gets defined in future. Since it only affects Book3S HV for now, the helper is added to the kvm_book3s.h header file. We use the helper in two places in kvmppc_run_core() as well for future-proofing, though we don't see RESUME_GUEST_NV in either place at present. [paulus@samba.org - combined 4 patches into one, rewrote description] Suggested-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
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@ -304,6 +304,11 @@ static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu)
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return vcpu->arch.fault_dar;
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}
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static inline bool is_kvmppc_resume_guest(int r)
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{
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return (r == RESUME_GUEST || r == RESUME_GUEST_NV);
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}
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/* Magic register values loaded into r3 and r4 before the 'sc' assembly
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* instruction for the OSI hypercalls */
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#define OSI_SC_MAGIC_R3 0x113724FA
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@ -1530,7 +1530,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
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vcpu->arch.trap = 0;
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if (vcpu->arch.ceded) {
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if (ret != RESUME_GUEST)
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if (!is_kvmppc_resume_guest(ret))
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kvmppc_end_cede(vcpu);
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else
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kvmppc_set_timer(vcpu);
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@ -1541,7 +1541,7 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
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vc->vcore_state = VCORE_INACTIVE;
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list_for_each_entry_safe(vcpu, vnext, &vc->runnable_threads,
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arch.run_list) {
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if (vcpu->arch.ret != RESUME_GUEST) {
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if (!is_kvmppc_resume_guest(vcpu->arch.ret)) {
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kvmppc_remove_runnable(vc, vcpu);
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wake_up(&vcpu->arch.cpu_run);
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}
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@ -1731,7 +1731,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
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vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
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srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
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}
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} while (r == RESUME_GUEST);
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} while (is_kvmppc_resume_guest(r));
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out:
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vcpu->arch.state = KVMPPC_VCPU_NOTREADY;
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