KVM: VMX: Enhance invalid guest state emulation
- Change returned handle_invalid_guest_state() to return relevant exit codes - Move triggering the emulation from vmx_vcpu_run() to vmx_handle_exit() - Return to userspace instead of repeatedly trying to emulate instructions that have already failed Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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arch/x86/kvm
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@ -107,7 +107,6 @@ struct vcpu_vmx {
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} rmode;
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} rmode;
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int vpid;
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int vpid;
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bool emulation_required;
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bool emulation_required;
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enum emulation_result invalid_state_emulation_result;
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/* Support for vnmi-less CPUs */
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/* Support for vnmi-less CPUs */
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int soft_vnmi_blocked;
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int soft_vnmi_blocked;
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@ -3322,35 +3321,37 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu)
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return 1;
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return 1;
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}
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}
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static void handle_invalid_guest_state(struct kvm_vcpu *vcpu)
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static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
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{
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{
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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struct vcpu_vmx *vmx = to_vmx(vcpu);
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enum emulation_result err = EMULATE_DONE;
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enum emulation_result err = EMULATE_DONE;
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int ret = 1;
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local_irq_enable();
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preempt_enable();
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while (!guest_state_valid(vcpu)) {
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while (!guest_state_valid(vcpu)) {
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err = emulate_instruction(vcpu, 0, 0, 0);
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err = emulate_instruction(vcpu, 0, 0, 0);
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if (err == EMULATE_DO_MMIO)
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if (err == EMULATE_DO_MMIO) {
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break;
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ret = 0;
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goto out;
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}
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if (err != EMULATE_DONE) {
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if (err != EMULATE_DONE) {
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kvm_report_emulation_failure(vcpu, "emulation failure");
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kvm_report_emulation_failure(vcpu, "emulation failure");
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break;
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vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
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vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
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ret = 0;
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goto out;
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}
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}
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if (signal_pending(current))
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if (signal_pending(current))
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break;
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goto out;
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if (need_resched())
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if (need_resched())
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schedule();
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schedule();
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}
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}
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preempt_disable();
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vmx->emulation_required = 0;
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local_irq_disable();
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out:
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return ret;
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vmx->invalid_state_emulation_result = err;
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}
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}
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/*
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/*
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@ -3406,13 +3407,9 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
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trace_kvm_exit(exit_reason, kvm_rip_read(vcpu));
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trace_kvm_exit(exit_reason, kvm_rip_read(vcpu));
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/* If we need to emulate an MMIO from handle_invalid_guest_state
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/* If guest state is invalid, start emulating */
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* we just return 0 */
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if (vmx->emulation_required && emulate_invalid_guest_state)
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if (vmx->emulation_required && emulate_invalid_guest_state) {
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return handle_invalid_guest_state(vcpu);
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if (guest_state_valid(vcpu))
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vmx->emulation_required = 0;
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return vmx->invalid_state_emulation_result != EMULATE_DO_MMIO;
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}
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/* Access CR3 don't cause VMExit in paging mode, so we need
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/* Access CR3 don't cause VMExit in paging mode, so we need
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* to sync with guest real CR3. */
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* to sync with guest real CR3. */
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@ -3607,11 +3604,10 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
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if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
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if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
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vmx->entry_time = ktime_get();
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vmx->entry_time = ktime_get();
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/* Handle invalid guest state instead of entering VMX */
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/* Don't enter VMX if guest state is invalid, let the exit handler
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if (vmx->emulation_required && emulate_invalid_guest_state) {
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start emulation until we arrive back to a valid state */
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handle_invalid_guest_state(vcpu);
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if (vmx->emulation_required && emulate_invalid_guest_state)
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return;
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return;
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}
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if (test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))
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if (test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))
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vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);
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vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);
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