---

yaml
---
r: 257984
b: refs/heads/master
c: ec378ae
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 801d342432190947928e18f893f073fd87cd8bdf
+refs/heads/master: ec378aeef9dfc7c4ba72e9bd6cd4bd6f7d5fd0cc

trunk/arch/x86/kvm/vmx.c

@@ -144,6 +144,15 @@ struct shared_msr_entry {
 	u64 mask;
 };
 
+/*
+ * The nested_vmx structure is part of vcpu_vmx, and holds information we need
+ * for correct emulation of VMX (i.e., nested VMX) on this vcpu.
+ */
+struct nested_vmx {
+	/* Has the level1 guest done vmxon? */
+	bool vmxon;
+};
+
 struct vcpu_vmx {
 	struct kvm_vcpu       vcpu;
 	unsigned long         host_rsp;
@@ -203,6 +212,9 @@ struct vcpu_vmx {
 	u32 exit_reason;
 
 	bool rdtscp_enabled;
+
+	/* Support for a guest hypervisor (nested VMX) */
+	struct nested_vmx nested;
 };
 
 enum segment_cache_field {
@@ -3933,6 +3945,99 @@ static int handle_invalid_op(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+/*
+ * Emulate the VMXON instruction.
+ * Currently, we just remember that VMX is active, and do not save or even
+ * inspect the argument to VMXON (the so-called "VMXON pointer") because we
+ * do not currently need to store anything in that guest-allocated memory
+ * region. Consequently, VMCLEAR and VMPTRLD also do not verify that the their
+ * argument is different from the VMXON pointer (which the spec says they do).
+ */
+static int handle_vmon(struct kvm_vcpu *vcpu)
+{
+	struct kvm_segment cs;
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	/* The Intel VMX Instruction Reference lists a bunch of bits that
+	 * are prerequisite to running VMXON, most notably cr4.VMXE must be
+	 * set to 1 (see vmx_set_cr4() for when we allow the guest to set this).
+	 * Otherwise, we should fail with #UD. We test these now:
+	 */
+	if (!kvm_read_cr4_bits(vcpu, X86_CR4_VMXE) ||
+	    !kvm_read_cr0_bits(vcpu, X86_CR0_PE) ||
+	    (vmx_get_rflags(vcpu) & X86_EFLAGS_VM)) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 1;
+	}
+
+	vmx_get_segment(vcpu, &cs, VCPU_SREG_CS);
+	if (is_long_mode(vcpu) && !cs.l) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 1;
+	}
+
+	if (vmx_get_cpl(vcpu)) {
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	vmx->nested.vmxon = true;
+
+	skip_emulated_instruction(vcpu);
+	return 1;
+}
+
+/*
+ * Intel's VMX Instruction Reference specifies a common set of prerequisites
+ * for running VMX instructions (except VMXON, whose prerequisites are
+ * slightly different). It also specifies what exception to inject otherwise.
+ */
+static int nested_vmx_check_permission(struct kvm_vcpu *vcpu)
+{
+	struct kvm_segment cs;
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	if (!vmx->nested.vmxon) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 0;
+	}
+
+	vmx_get_segment(vcpu, &cs, VCPU_SREG_CS);
+	if ((vmx_get_rflags(vcpu) & X86_EFLAGS_VM) ||
+	    (is_long_mode(vcpu) && !cs.l)) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 0;
+	}
+
+	if (vmx_get_cpl(vcpu)) {
+		kvm_inject_gp(vcpu, 0);
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * Free whatever needs to be freed from vmx->nested when L1 goes down, or
+ * just stops using VMX.
+ */
+static void free_nested(struct vcpu_vmx *vmx)
+{
+	if (!vmx->nested.vmxon)
+		return;
+	vmx->nested.vmxon = false;
+}
+
+/* Emulate the VMXOFF instruction */
+static int handle_vmoff(struct kvm_vcpu *vcpu)
+{
+	if (!nested_vmx_check_permission(vcpu))
+		return 1;
+	free_nested(to_vmx(vcpu));
+	skip_emulated_instruction(vcpu);
+	return 1;
+}
+
 /*
  * The exit handlers return 1 if the exit was handled fully and guest execution
  * may resume.  Otherwise they set the kvm_run parameter to indicate what needs
@@ -3961,8 +4066,8 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_VMREAD]                  = handle_vmx_insn,
 	[EXIT_REASON_VMRESUME]                = handle_vmx_insn,
 	[EXIT_REASON_VMWRITE]                 = handle_vmx_insn,
-	[EXIT_REASON_VMOFF]                   = handle_vmx_insn,
-	[EXIT_REASON_VMON]                    = handle_vmx_insn,
+	[EXIT_REASON_VMOFF]                   = handle_vmoff,
+	[EXIT_REASON_VMON]                    = handle_vmon,
 	[EXIT_REASON_TPR_BELOW_THRESHOLD]     = handle_tpr_below_threshold,
 	[EXIT_REASON_APIC_ACCESS]             = handle_apic_access,
 	[EXIT_REASON_WBINVD]                  = handle_wbinvd,
@@ -4363,6 +4468,7 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
 	free_vpid(vmx);
+	free_nested(vmx);
 	free_loaded_vmcs(vmx->loaded_vmcs);
 	kfree(vmx->guest_msrs);
 	kvm_vcpu_uninit(vcpu);