[PATCH 1/5] Nested VMX patch 1 implements vmon and vmoff

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From: Orit Wasserman <oritw@xxxxxxxxxx>

---
 arch/x86/kvm/svm.c |    3 -
 arch/x86/kvm/vmx.c |  217 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c |    6 +-
 arch/x86/kvm/x86.h |    2 +
 4 files changed, 222 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2df9b45..3c1f22a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -124,9 +124,6 @@ static int npt = 1;
 
 module_param(npt, int, S_IRUGO);
 
-static int nested = 1;
-module_param(nested, int, S_IRUGO);
-
 static void svm_flush_tlb(struct kvm_vcpu *vcpu);
 static void svm_complete_interrupts(struct vcpu_svm *svm);
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 78101dd..71bd91a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -67,6 +67,11 @@ struct vmcs {
 	char data[0];
 };
 
+struct nested_vmx {
+	/* Has the level1 guest done vmxon? */
+	bool vmxon;
+};
+
 struct vcpu_vmx {
 	struct kvm_vcpu       vcpu;
 	struct list_head      local_vcpus_link;
@@ -114,6 +119,9 @@ struct vcpu_vmx {
 	ktime_t entry_time;
 	s64 vnmi_blocked_time;
 	u32 exit_reason;
+
+	/* Nested vmx */
+	struct nested_vmx nested;
 };
 
 static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
@@ -967,6 +975,95 @@ static void guest_write_tsc(u64 guest_tsc, u64 host_tsc)
 }
 
 /*
+ * Handles msr read for nested virtualization
+ */
+static int nested_vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index,
+			      u64 *pdata)
+{
+	u64 vmx_msr = 0;
+
+	switch (msr_index) {
+	case MSR_IA32_FEATURE_CONTROL:
+		*pdata = 0;
+		break;
+	case MSR_IA32_VMX_BASIC:
+		*pdata = 0;
+		rdmsrl(MSR_IA32_VMX_BASIC, vmx_msr);
+		*pdata = (vmx_msr & 0x00ffffcfffffffff);
+		break;
+	case MSR_IA32_VMX_PINBASED_CTLS:
+		rdmsrl(MSR_IA32_VMX_PINBASED_CTLS, vmx_msr);
+		*pdata = (PIN_BASED_EXT_INTR_MASK & vmcs_config.pin_based_exec_ctrl) |
+			(PIN_BASED_NMI_EXITING & vmcs_config.pin_based_exec_ctrl) |
+			(PIN_BASED_VIRTUAL_NMIS & vmcs_config.pin_based_exec_ctrl);
+		break;
+	case MSR_IA32_VMX_PROCBASED_CTLS:
+	{
+		u32 vmx_msr_high, vmx_msr_low;
+		u32 control = CPU_BASED_HLT_EXITING |
+#ifdef CONFIG_X86_64
+			CPU_BASED_CR8_LOAD_EXITING |
+			CPU_BASED_CR8_STORE_EXITING |
+#endif
+			CPU_BASED_CR3_LOAD_EXITING |
+			CPU_BASED_CR3_STORE_EXITING |
+			CPU_BASED_USE_IO_BITMAPS |
+			CPU_BASED_MOV_DR_EXITING |
+			CPU_BASED_USE_TSC_OFFSETING |
+			CPU_BASED_INVLPG_EXITING |
+			CPU_BASED_TPR_SHADOW |
+			CPU_BASED_USE_MSR_BITMAPS |
+			CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
+
+		rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, vmx_msr_low, vmx_msr_high);
+
+		control &= vmx_msr_high; /* bit == 0 in high word ==> must be zero */
+		control |= vmx_msr_low;  /* bit == 1 in low word  ==> must be one  */
+
+		*pdata = (CPU_BASED_HLT_EXITING & control) |
+#ifdef CONFIG_X86_64
+			(CPU_BASED_CR8_LOAD_EXITING & control) |
+			(CPU_BASED_CR8_STORE_EXITING & control) |
+#endif
+			(CPU_BASED_CR3_LOAD_EXITING & control) |
+			(CPU_BASED_CR3_STORE_EXITING & control) |
+			(CPU_BASED_USE_IO_BITMAPS & control) |
+			(CPU_BASED_MOV_DR_EXITING & control) |
+			(CPU_BASED_USE_TSC_OFFSETING & control) |
+			(CPU_BASED_INVLPG_EXITING & control) ;
+
+		if (cpu_has_secondary_exec_ctrls())
+			*pdata |= CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
+
+		if (vm_need_tpr_shadow(vcpu->kvm))
+			*pdata |= CPU_BASED_TPR_SHADOW;
+		break;
+	}
+	case MSR_IA32_VMX_EXIT_CTLS:
+		*pdata = 0;
+#ifdef CONFIG_X86_64
+		*pdata |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
+#endif
+		break;
+	case MSR_IA32_VMX_ENTRY_CTLS:
+		*pdata = 0;
+		break;
+	case MSR_IA32_VMX_PROCBASED_CTLS2:
+		*pdata = 0;
+		if (vm_need_virtualize_apic_accesses(vcpu->kvm))
+			*pdata |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+		break;
+	case MSR_IA32_VMX_EPT_VPID_CAP:
+		*pdata = 0;
+		break;
+	default:
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
  * Reads an msr value (of 'msr_index') into 'pdata'.
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
@@ -1005,6 +1102,9 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 		data = vmcs_readl(GUEST_SYSENTER_ESP);
 		break;
 	default:
+		if (nested &&
+		    !nested_vmx_get_msr(vcpu, msr_index, &data))
+			break;
 		vmx_load_host_state(to_vmx(vcpu));
 		msr = find_msr_entry(to_vmx(vcpu), msr_index);
 		if (msr) {
@@ -1019,6 +1119,27 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 }
 
 /*
+ * Writes msr value for nested virtualization
+ * Returns 0 on success, non-0 otherwise.
+ */
+static int nested_vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
+{
+	switch (msr_index) {
+	case MSR_IA32_FEATURE_CONTROL:
+		if ((data & (FEATURE_CONTROL_LOCKED |
+			     FEATURE_CONTROL_VMXON_ENABLED))
+		    != (FEATURE_CONTROL_LOCKED |
+			FEATURE_CONTROL_VMXON_ENABLED))
+			return 1;
+		break;
+	default:
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
  * Writes msr value into into the appropriate "register".
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
@@ -1064,6 +1185,9 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 		}
 		/* Otherwise falls through to kvm_set_msr_common */
 	default:
+		if (nested &&
+		    !nested_vmx_set_msr(vcpu, msr_index, data))
+			break;
 		vmx_load_host_state(vmx);
 		msr = find_msr_entry(vmx, msr_index);
 		if (msr) {
@@ -3095,12 +3219,101 @@ static int handle_vmcall(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+/*
+ * Check to see if vcpu can execute vmx command
+ * Inject the corrseponding exception
+ */
+static int nested_vmx_check_permission(struct kvm_vcpu *vcpu)
+{
+	struct kvm_segment cs;
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+	struct kvm_msr_entry *msr;
+
+	vmx_get_segment(vcpu, &cs, VCPU_SREG_CS);
+
+	if (!vmx->nested.vmxon) {
+		printk(KERN_DEBUG "%s: vmx not on\n", __func__);
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 0;
+	}
+
+	msr = find_msr_entry(vmx, MSR_EFER);
+
+	if ((vmx_get_rflags(vcpu) & X86_EFLAGS_VM) ||
+		 ((msr->data & EFER_LMA) && !cs.l)) {
+		printk(KERN_DEBUG "%s: invalid mode cs.l %d lma %llu\n",
+		       __func__, cs.l, msr->data & EFER_LMA);
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 0;
+	}
+
+	if (vmx_get_cpl(vcpu)) {
+		kvm_inject_gp(vcpu, 0);
+		return 0;
+	}
+
+	return 1;
+}
+
 static int handle_vmx_insn(struct kvm_vcpu *vcpu)
 {
 	kvm_queue_exception(vcpu, UD_VECTOR);
 	return 1;
 }
 
+static int handle_vmoff(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	if (!nested_vmx_check_permission(vcpu))
+		return 1;
+
+	vmx->nested.vmxon = 0;
+
+	skip_emulated_instruction(vcpu);
+	return 1;
+}
+
+static int handle_vmon(struct kvm_vcpu *vcpu)
+{
+	struct kvm_segment cs;
+	struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+	if (!nested) {
+		printk(KERN_DEBUG "%s: nested vmx not enabled\n", __func__);
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return 1;
+	}
+
+	vmx_get_segment(vcpu, &cs, VCPU_SREG_CS);
+
+	if (!(vcpu->arch.cr4 & X86_CR4_VMXE) ||
+	    !(vcpu->arch.cr0 & X86_CR0_PE) ||
+	    (vmx_get_rflags(vcpu) & X86_EFLAGS_VM)) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		printk(KERN_INFO "%s invalid register state\n", __func__);
+		return 1;
+	}
+#ifdef CONFIG_X86_64
+	if (((find_msr_entry(to_vmx(vcpu),
+			     MSR_EFER)->data & EFER_LMA) && !cs.l)) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		printk(KERN_INFO "%s invalid register state\n", __func__);
+		return 1;
+	}
+#endif
+	if (vmx_get_cpl(vcpu)) {
+		printk(KERN_INFO "%s no permission\n", __func__);
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	vmx->nested.vmxon = 1;
+
+	skip_emulated_instruction(vcpu);
+	return 1;
+}
+
 static int handle_invlpg(struct kvm_vcpu *vcpu)
 {
 	unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
@@ -3376,8 +3589,8 @@ 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,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8b3a169..9c39092 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -87,6 +87,10 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops);
 int ignore_msrs = 0;
 module_param_named(ignore_msrs, ignore_msrs, bool, S_IRUGO | S_IWUSR);
 
+int nested = 1;
+EXPORT_SYMBOL_GPL(nested);
+module_param(nested, int, S_IRUGO);
+
 struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ "pf_fixed", VCPU_STAT(pf_fixed) },
 	{ "pf_guest", VCPU_STAT(pf_guest) },
@@ -373,7 +377,7 @@ void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 		return;
 	}
 
-	if (cr4 & X86_CR4_VMXE) {
+	if (cr4 & X86_CR4_VMXE && !nested) {
 		printk(KERN_DEBUG "set_cr4: #GP, setting VMXE\n");
 		kvm_inject_gp(vcpu, 0);
 		return;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 5eadea5..57204cb 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -35,4 +35,6 @@ static inline bool kvm_exception_is_soft(unsigned int nr)
 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
                                              u32 function, u32 index);
 
+extern int nested;
+
 #endif
-- 
1.6.0.4

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