kvm: vmx: add nested virtualization support for xsaves

Add nested virtualization support for xsaves.
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -216,6 +216,7 @@ struct __packed vmcs12 {
 	u64 virtual_apic_page_addr;
 	u64 apic_access_addr;
 	u64 ept_pointer;
+	u64 xss_exit_bitmap;
 	u64 guest_physical_address;
 	u64 vmcs_link_pointer;
 	u64 guest_ia32_debugctl;
@@ -618,6 +619,7 @@ static const unsigned short vmcs_field_to_offset_table[] = {
 	FIELD64(VIRTUAL_APIC_PAGE_ADDR, virtual_apic_page_addr),
 	FIELD64(APIC_ACCESS_ADDR, apic_access_addr),
 	FIELD64(EPT_POINTER, ept_pointer),
+	FIELD64(XSS_EXIT_BITMAP, xss_exit_bitmap),
 	FIELD64(GUEST_PHYSICAL_ADDRESS, guest_physical_address),
 	FIELD64(VMCS_LINK_POINTER, vmcs_link_pointer),
 	FIELD64(GUEST_IA32_DEBUGCTL, guest_ia32_debugctl),
@@ -1104,6 +1106,12 @@ static inline int nested_cpu_has_ept(struct vmcs12 *vmcs12)
 	return nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENABLE_EPT);
 }
 
+static inline bool nested_cpu_has_xsaves(struct vmcs12 *vmcs12)
+{
+	return nested_cpu_has2(vmcs12, SECONDARY_EXEC_XSAVES) &&
+		vmx_xsaves_supported();
+}
+
 static inline bool is_exception(u32 intr_info)
 {
 	return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -2392,7 +2400,8 @@ static __init void nested_vmx_setup_ctls_msrs(void)
 	nested_vmx_secondary_ctls_high &=
 		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
 		SECONDARY_EXEC_UNRESTRICTED_GUEST |
-		SECONDARY_EXEC_WBINVD_EXITING;
+		SECONDARY_EXEC_WBINVD_EXITING |
+		SECONDARY_EXEC_XSAVES;
 
 	if (enable_ept) {
 		/* nested EPT: emulate EPT also to L1 */
@@ -7286,6 +7295,14 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
 		return nested_cpu_has2(vmcs12, SECONDARY_EXEC_WBINVD_EXITING);
 	case EXIT_REASON_XSETBV:
 		return 1;
+	case EXIT_REASON_XSAVES: case EXIT_REASON_XRSTORS:
+		/*
+		 * This should never happen, since it is not possible to
+		 * set XSS to a non-zero value---neither in L1 nor in L2.
+		 * If if it were, XSS would have to be checked against
+		 * the XSS exit bitmap in vmcs12.
+		 */
+		return nested_cpu_has2(vmcs12, SECONDARY_EXEC_XSAVES);
 	default:
 		return 1;
 	}
@@ -8342,6 +8359,8 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	vmcs_writel(GUEST_SYSENTER_ESP, vmcs12->guest_sysenter_esp);
 	vmcs_writel(GUEST_SYSENTER_EIP, vmcs12->guest_sysenter_eip);
 
+	if (nested_cpu_has_xsaves(vmcs12))
+		vmcs_write64(XSS_EXIT_BITMAP, vmcs12->xss_exit_bitmap);
 	vmcs_write64(VMCS_LINK_POINTER, -1ull);
 
 	exec_control = vmcs12->pin_based_vm_exec_control;
@@ -8982,6 +9001,8 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 	vmcs12->guest_sysenter_eip = vmcs_readl(GUEST_SYSENTER_EIP);
 	if (vmx_mpx_supported())
 		vmcs12->guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
+	if (nested_cpu_has_xsaves(vmcs12))
+		vmcs12->xss_exit_bitmap = vmcs_read64(XSS_EXIT_BITMAP);
 
 	/* update exit information fields: */