[PATCH v3 23/27] KVM: nVMX: Add a prerequisite to SHADOW_FIELD_R[OW] macros

[Xin Li (Intel)]

From: Xin Li <xin3.li@xxxxxxxxx>

Add a prerequisite for accessing VMCS fields referenced in macros
SHADOW_FIELD_R[OW], because a VMCS field may not exist on some CPUs.

Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
---

Change since v2:
* Add __SHADOW_FIELD_R[OW] for better readability or maintability (Sean).
---
 arch/x86/kvm/vmx/nested.c             | 79 +++++++++++++++++++--------
 arch/x86/kvm/vmx/vmcs_shadow_fields.h | 33 ++++++++---
 2 files changed, 79 insertions(+), 33 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 42e43eb7561f..7f3ac558ace5 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -54,14 +54,14 @@ struct shadow_vmcs_field {
 	u16	offset;
 };
 static struct shadow_vmcs_field shadow_read_only_fields[] = {
-#define SHADOW_FIELD_RO(x, y) { x, offsetof(struct vmcs12, y) },
+#define __SHADOW_FIELD_RO(x, y, c) { x, offsetof(struct vmcs12, y) },
 #include "vmcs_shadow_fields.h"
 };
 static int max_shadow_read_only_fields =
 	ARRAY_SIZE(shadow_read_only_fields);
 
 static struct shadow_vmcs_field shadow_read_write_fields[] = {
-#define SHADOW_FIELD_RW(x, y) { x, offsetof(struct vmcs12, y) },
+#define __SHADOW_FIELD_RW(x, y, c) { x, offsetof(struct vmcs12, y) },
 #include "vmcs_shadow_fields.h"
 };
 static int max_shadow_read_write_fields =
@@ -84,6 +84,17 @@ static void init_vmcs_shadow_fields(void)
 			pr_err("Missing field from shadow_read_only_field %x\n",
 			       field + 1);
 
+		switch (field) {
+#define __SHADOW_FIELD_RO(x, y, c)		\
+		case x:				\
+			if (!(c))		\
+				continue;	\
+			break;
+#include "vmcs_shadow_fields.h"
+		default:
+			break;
+		}
+
 		clear_bit(field, vmx_vmread_bitmap);
 		if (field & 1)
 #ifdef CONFIG_X86_64
@@ -109,24 +120,13 @@ static void init_vmcs_shadow_fields(void)
 			  field <= GUEST_TR_AR_BYTES,
 			  "Update vmcs12_write_any() to drop reserved bits from AR_BYTES");
 
-		/*
-		 * PML and the preemption timer can be emulated, but the
-		 * processor cannot vmwrite to fields that don't exist
-		 * on bare metal.
-		 */
 		switch (field) {
-		case GUEST_PML_INDEX:
-			if (!cpu_has_vmx_pml())
-				continue;
-			break;
-		case VMX_PREEMPTION_TIMER_VALUE:
-			if (!cpu_has_vmx_preemption_timer())
-				continue;
-			break;
-		case GUEST_INTR_STATUS:
-			if (!cpu_has_vmx_apicv())
-				continue;
+#define __SHADOW_FIELD_RW(x, y, c)		\
+		case x:				\
+			if (!(c))		\
+				continue;	\
 			break;
+#include "vmcs_shadow_fields.h"
 		default:
 			break;
 		}
@@ -1586,8 +1586,8 @@ int vmx_get_vmx_msr(struct nested_vmx_msrs *msrs, u32 msr_index, u64 *pdata)
 /*
  * Copy the writable VMCS shadow fields back to the VMCS12, in case they have
  * been modified by the L1 guest.  Note, "writable" in this context means
- * "writable by the guest", i.e. tagged SHADOW_FIELD_RW; the set of
- * fields tagged SHADOW_FIELD_RO may or may not align with the "read-only"
+ * "writable by the guest", i.e. tagged __SHADOW_FIELD_RW; the set of
+ * fields tagged __SHADOW_FIELD_RO may or may not align with the "read-only"
  * VM-exit information fields (which are actually writable if the vCPU is
  * configured to support "VMWRITE to any supported field in the VMCS").
  */
@@ -1608,6 +1608,18 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx)
 
 	for (i = 0; i < max_shadow_read_write_fields; i++) {
 		field = shadow_read_write_fields[i];
+
+		switch (field.encoding) {
+#define __SHADOW_FIELD_RW(x, y, c)		\
+		case x:				\
+			if (!(c))		\
+				continue;	\
+			break;
+#include "vmcs_shadow_fields.h"
+		default:
+			break;
+		}
+
 		val = __vmcs_readl(field.encoding);
 		vmcs12_write_any(vmcs12, field.encoding, field.offset, val);
 	}
@@ -1642,6 +1654,23 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx)
 	for (q = 0; q < ARRAY_SIZE(fields); q++) {
 		for (i = 0; i < max_fields[q]; i++) {
 			field = fields[q][i];
+
+			switch (field.encoding) {
+#define __SHADOW_FIELD_RO(x, y, c)			\
+			case x:				\
+				if (!(c))		\
+					continue;	\
+				break;
+#define __SHADOW_FIELD_RW(x, y, c)			\
+			case x:				\
+				if (!(c))		\
+					continue;	\
+				break;
+#include "vmcs_shadow_fields.h"
+			default:
+				break;
+			}
+
 			val = vmcs12_read_any(vmcs12, field.encoding,
 					      field.offset);
 			__vmcs_writel(field.encoding, val);
@@ -5590,9 +5619,10 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
 static bool is_shadow_field_rw(unsigned long field)
 {
 	switch (field) {
-#define SHADOW_FIELD_RW(x, y) case x:
+#define __SHADOW_FIELD_RW(x, y, c)	\
+	case x:				\
+		return c;
 #include "vmcs_shadow_fields.h"
-		return true;
 	default:
 		break;
 	}
@@ -5602,9 +5632,10 @@ static bool is_shadow_field_rw(unsigned long field)
 static bool is_shadow_field_ro(unsigned long field)
 {
 	switch (field) {
-#define SHADOW_FIELD_RO(x, y) case x:
+#define __SHADOW_FIELD_RO(x, y, c)	\
+	case x:				\
+		return c;
 #include "vmcs_shadow_fields.h"
-		return true;
 	default:
 		break;
 	}
diff --git a/arch/x86/kvm/vmx/vmcs_shadow_fields.h b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
index cad128d1657b..53b64dce1309 100644
--- a/arch/x86/kvm/vmx/vmcs_shadow_fields.h
+++ b/arch/x86/kvm/vmx/vmcs_shadow_fields.h
@@ -1,14 +1,17 @@
-#if !defined(SHADOW_FIELD_RO) && !defined(SHADOW_FIELD_RW)
+#if !defined(__SHADOW_FIELD_RO) && !defined(__SHADOW_FIELD_RW)
 BUILD_BUG_ON(1)
 #endif
 
-#ifndef SHADOW_FIELD_RO
-#define SHADOW_FIELD_RO(x, y)
+#ifndef __SHADOW_FIELD_RO
+#define __SHADOW_FIELD_RO(x, y, c)
 #endif
-#ifndef SHADOW_FIELD_RW
-#define SHADOW_FIELD_RW(x, y)
+#ifndef __SHADOW_FIELD_RW
+#define __SHADOW_FIELD_RW(x, y, c)
 #endif
 
+#define SHADOW_FIELD_RO(x, y) __SHADOW_FIELD_RO(x, y, true)
+#define SHADOW_FIELD_RW(x, y) __SHADOW_FIELD_RW(x, y, true)
+
 /*
  * We do NOT shadow fields that are modified when L0
  * traps and emulates any vmx instruction (e.g. VMPTRLD,
@@ -32,8 +35,12 @@ BUILD_BUG_ON(1)
  */
 
 /* 16-bits */
-SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status)
-SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index)
+__SHADOW_FIELD_RW(GUEST_INTR_STATUS, guest_intr_status, cpu_has_vmx_apicv())
+/*
+ * PML can be emulated, but the processor cannot vmwrite to the VMCS field
+ * GUEST_PML_INDEX that doesn't exist on bare metal.
+ */
+__SHADOW_FIELD_RW(GUEST_PML_INDEX, guest_pml_index, cpu_has_vmx_pml())
 SHADOW_FIELD_RW(HOST_FS_SELECTOR, host_fs_selector)
 SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector)
 
@@ -41,9 +48,9 @@ SHADOW_FIELD_RW(HOST_GS_SELECTOR, host_gs_selector)
 SHADOW_FIELD_RO(VM_EXIT_REASON, vm_exit_reason)
 SHADOW_FIELD_RO(VM_EXIT_INTR_INFO, vm_exit_intr_info)
 SHADOW_FIELD_RO(VM_EXIT_INSTRUCTION_LEN, vm_exit_instruction_len)
+SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code)
 SHADOW_FIELD_RO(IDT_VECTORING_INFO_FIELD, idt_vectoring_info_field)
 SHADOW_FIELD_RO(IDT_VECTORING_ERROR_CODE, idt_vectoring_error_code)
-SHADOW_FIELD_RO(VM_EXIT_INTR_ERROR_CODE, vm_exit_intr_error_code)
 SHADOW_FIELD_RO(GUEST_CS_AR_BYTES, guest_cs_ar_bytes)
 SHADOW_FIELD_RO(GUEST_SS_AR_BYTES, guest_ss_ar_bytes)
 SHADOW_FIELD_RW(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control)
@@ -54,7 +61,12 @@ SHADOW_FIELD_RW(VM_ENTRY_INTR_INFO_FIELD, vm_entry_intr_info_field)
 SHADOW_FIELD_RW(VM_ENTRY_INSTRUCTION_LEN, vm_entry_instruction_len)
 SHADOW_FIELD_RW(TPR_THRESHOLD, tpr_threshold)
 SHADOW_FIELD_RW(GUEST_INTERRUPTIBILITY_INFO, guest_interruptibility_info)
-SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value)
+/*
+ * The preemption timer can be emulated, but the processor cannot vmwrite to
+ * the VMCS field VMX_PREEMPTION_TIMER_VALUE that doesn't exist on bare metal.
+ */
+__SHADOW_FIELD_RW(VMX_PREEMPTION_TIMER_VALUE, vmx_preemption_timer_value,
+		  cpu_has_vmx_preemption_timer())
 
 /* Natural width */
 SHADOW_FIELD_RO(EXIT_QUALIFICATION, exit_qualification)
@@ -77,3 +89,6 @@ SHADOW_FIELD_RO(GUEST_PHYSICAL_ADDRESS_HIGH, guest_physical_address)
 
 #undef SHADOW_FIELD_RO
 #undef SHADOW_FIELD_RW
+
+#undef __SHADOW_FIELD_RO
+#undef __SHADOW_FIELD_RW
-- 
2.46.2