Commit 80ced186 authored by Mohammed Gamal's avatar Mohammed Gamal Committed by Avi Kivity
Browse files

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: default avatarMohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent abcf14b5

arch/x86/kvm/vmx.c

+20 −24
Original line number Diff line number Diff line
@@ -107,7 +107,6 @@ struct vcpu_vmx { 
	} rmode;

	int vpid;

	bool emulation_required;

	enum emulation_result invalid_state_emulation_result;



	/* Support for vnmi-less CPUs */

	int soft_vnmi_blocked;
@@ -3322,35 +3321,37 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu) 
	return 1;

}



static void handle_invalid_guest_state(struct kvm_vcpu *vcpu)

static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	enum emulation_result err = EMULATE_DONE;



	local_irq_enable();

	preempt_enable();

	int ret = 1;



	while (!guest_state_valid(vcpu)) {

		err = emulate_instruction(vcpu, 0, 0, 0);



		if (err == EMULATE_DO_MMIO)

			break;

		if (err == EMULATE_DO_MMIO) {

			ret = 0;

			goto out;

		}



		if (err != EMULATE_DONE) {

			kvm_report_emulation_failure(vcpu, "emulation failure");

			break;

			vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;

			ret = 0;

			goto out;

		}



		if (signal_pending(current))

			break;

			goto out;

		if (need_resched())

			schedule();

	}



	preempt_disable();

	local_irq_disable();



	vmx->invalid_state_emulation_result = err;

	vmx->emulation_required = 0;

out:

	return ret;

}



/*
@@ -3406,13 +3407,9 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) 


	trace_kvm_exit(exit_reason, kvm_rip_read(vcpu));



	/* If we need to emulate an MMIO from handle_invalid_guest_state

	 * we just return 0 */

	if (vmx->emulation_required && emulate_invalid_guest_state) {

		if (guest_state_valid(vcpu))

			vmx->emulation_required = 0;

		return vmx->invalid_state_emulation_result != EMULATE_DO_MMIO;

	}

	/* If guest state is invalid, start emulating */

	if (vmx->emulation_required && emulate_invalid_guest_state)

		return handle_invalid_guest_state(vcpu);



	/* Access CR3 don't cause VMExit in paging mode, so we need

	 * to sync with guest real CR3. */
@@ -3607,11 +3604,10 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) 
	if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))

		vmx->entry_time = ktime_get();



	/* Handle invalid guest state instead of entering VMX */

	if (vmx->emulation_required && emulate_invalid_guest_state) {

		handle_invalid_guest_state(vcpu);

	/* Don't enter VMX if guest state is invalid, let the exit handler

	   start emulation until we arrive back to a valid state */

	if (vmx->emulation_required && emulate_invalid_guest_state)

		return;

	}



	if (test_bit(VCPU_REGS_RSP, (unsigned long *)&vcpu->arch.regs_dirty))

		vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);

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