[PATCH v2 1/4] nested vmx: clean up for vmcs12 read and write

[Dongxiao Xu <dongxiao.xu@intel.com>]

abstract vmcs12_read and vmcs12_write functions to do the vmcs12
read/write operations.

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
---
 arch/x86/kvm/vmx.c |   85 +++++++++++++++++++++++++---------------------------
 1 files changed, 41 insertions(+), 44 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f858159..2f8344f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -583,10 +583,15 @@ static const unsigned short vmcs_field_to_offset_table[] = {
 };
 static const int max_vmcs_field = ARRAY_SIZE(vmcs_field_to_offset_table);
 
-static inline short vmcs_field_to_offset(unsigned long field)
+static inline bool vmcs_field_valid(unsigned long field)
 {
 	if (field >= max_vmcs_field || vmcs_field_to_offset_table[field] == 0)
-		return -1;
+		return 0;
+	return 1;
+}
+
+static inline short vmcs_field_to_offset(unsigned long field)
+{
 	return vmcs_field_to_offset_table[field];
 }
 
@@ -5407,32 +5412,45 @@ static inline int vmcs_field_readonly(unsigned long field)
  * some of the bits we return here (e.g., on 32-bit guests, only 32 bits of
  * 64-bit fields are to be returned).
  */
-static inline bool vmcs12_read_any(struct kvm_vcpu *vcpu,
-					unsigned long field, u64 *ret)
+static inline u64 vmcs12_read(struct kvm_vcpu *vcpu, unsigned long field)
 {
-	short offset = vmcs_field_to_offset(field);
-	char *p;
+	char *p = ((char *)(get_vmcs12(vcpu))) + vmcs_field_to_offset(field);
 
-	if (offset < 0)
-		return 0;
+	switch (vmcs_field_type(field)) {
+	case VMCS_FIELD_TYPE_NATURAL_WIDTH:
+		return *((natural_width *)p);
+	case VMCS_FIELD_TYPE_U16:
+		return *((u16 *)p);
+	case VMCS_FIELD_TYPE_U32:
+		return *((u32 *)p);
+	case VMCS_FIELD_TYPE_U64:
+		return *((u64 *)p);
+	default:
+		return 0; /* can never happen. */
+	}
+}
 
-	p = ((char *)(get_vmcs12(vcpu))) + offset;
+static inline void vmcs12_write(struct kvm_vcpu *vcpu,
+				unsigned long field,
+				u64 value)
+{
+	char *p = ((char *)(get_vmcs12(vcpu))) + vmcs_field_to_offset(field);
 
 	switch (vmcs_field_type(field)) {
 	case VMCS_FIELD_TYPE_NATURAL_WIDTH:
-		*ret = *((natural_width *)p);
-		return 1;
+		*(natural_width *)p = value;
+		break;
 	case VMCS_FIELD_TYPE_U16:
-		*ret = *((u16 *)p);
-		return 1;
+		*(u16 *)p = value;
+		break;
 	case VMCS_FIELD_TYPE_U32:
-		*ret = *((u32 *)p);
-		return 1;
+		*(u32 *)p = value;
+		break;
 	case VMCS_FIELD_TYPE_U64:
-		*ret = *((u64 *)p);
-		return 1;
+		*(u64 *)p = value;
+		break;
 	default:
-		return 0; /* can never happen. */
+		break; /* can never happen. */
 	}
 }
 
@@ -5465,12 +5483,13 @@ static int handle_vmread(struct kvm_vcpu *vcpu)
 
 	/* Decode instruction info and find the field to read */
 	field = kvm_register_read(vcpu, (((vmx_instruction_info) >> 28) & 0xf));
-	/* Read the field, zero-extended to a u64 field_value */
-	if (!vmcs12_read_any(vcpu, field, &field_value)) {
+	if (!vmcs_field_valid(field)) {
 		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
 		skip_emulated_instruction(vcpu);
 		return 1;
 	}
+	/* Read the field, zero-extended to a u64 field_value */
+	field_value = vmcs12_read(vcpu, field);
 	/*
 	 * Now copy part of this value to register or memory, as requested.
 	 * Note that the number of bits actually copied is 32 or 64 depending
@@ -5500,8 +5519,6 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
 	gva_t gva;
 	unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
 	u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
-	char *p;
-	short offset;
 	/* The value to write might be 32 or 64 bits, depending on L1's long
 	 * mode, and eventually we need to write that into a field of several
 	 * possible lengths. The code below first zero-extends the value to 64
@@ -5537,33 +5554,13 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
 		skip_emulated_instruction(vcpu);
 		return 1;
 	}
-
-	offset = vmcs_field_to_offset(field);
-	if (offset < 0) {
+	if (!vmcs_field_valid(field)) {
 		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
 		skip_emulated_instruction(vcpu);
 		return 1;
 	}
-	p = ((char *) get_vmcs12(vcpu)) + offset;
 
-	switch (vmcs_field_type(field)) {
-	case VMCS_FIELD_TYPE_U16:
-		*(u16 *)p = field_value;
-		break;
-	case VMCS_FIELD_TYPE_U32:
-		*(u32 *)p = field_value;
-		break;
-	case VMCS_FIELD_TYPE_U64:
-		*(u64 *)p = field_value;
-		break;
-	case VMCS_FIELD_TYPE_NATURAL_WIDTH:
-		*(natural_width *)p = field_value;
-		break;
-	default:
-		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
-		skip_emulated_instruction(vcpu);
-		return 1;
-	}
+	vmcs12_write(vcpu, field, field_value);
 
 	nested_vmx_succeed(vcpu);
 	skip_emulated_instruction(vcpu);
-- 
1.7.1