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Commit a2ae9df7 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

kvm: x86: vmx: avoid returning bool to distinguish success from error 



Return a negative error code instead, and WARN() when we should be covering
the entire 2-bit space of vmcs_field_type's return value.  For increased
robustness, add a BUILD_BUG_ON checking the range of vmcs_field_to_offset.

Suggested-by: default avatarTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 34a1cd60

arch/x86/kvm/vmx.c

+32 −21
Original line number Diff line number Diff line
@@ -720,12 +720,15 @@ static const unsigned short vmcs_field_to_offset_table[] = { 
	FIELD(HOST_RSP, host_rsp),

	FIELD(HOST_RIP, host_rip),

};

static const int max_vmcs_field = ARRAY_SIZE(vmcs_field_to_offset_table);



static inline short vmcs_field_to_offset(unsigned long field)

{

	if (field >= max_vmcs_field || vmcs_field_to_offset_table[field] == 0)

		return -1;

	BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX);



	if (field >= ARRAY_SIZE(vmcs_field_to_offset_table) ||

	    vmcs_field_to_offset_table[field] == 0)

		return -ENOENT;



	return vmcs_field_to_offset_table[field];

}
@@ -6492,58 +6495,60 @@ 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,

static inline int vmcs12_read_any(struct kvm_vcpu *vcpu,

				  unsigned long field, u64 *ret)

{

	short offset = vmcs_field_to_offset(field);

	char *p;



	if (offset < 0)

		return 0;

		return offset;



	p = ((char *)(get_vmcs12(vcpu))) + offset;



	switch (vmcs_field_type(field)) {

	case VMCS_FIELD_TYPE_NATURAL_WIDTH:

		*ret = *((natural_width *)p);

		return 1;

		return 0;

	case VMCS_FIELD_TYPE_U16:

		*ret = *((u16 *)p);

		return 1;

		return 0;

	case VMCS_FIELD_TYPE_U32:

		*ret = *((u32 *)p);

		return 1;

		return 0;

	case VMCS_FIELD_TYPE_U64:

		*ret = *((u64 *)p);

		return 1;

		return 0;

	default:

		return 0; /* can never happen. */

		WARN_ON(1);

		return -ENOENT;

	}

}





static inline bool vmcs12_write_any(struct kvm_vcpu *vcpu,

static inline int vmcs12_write_any(struct kvm_vcpu *vcpu,

				   unsigned long field, u64 field_value){

	short offset = vmcs_field_to_offset(field);

	char *p = ((char *) get_vmcs12(vcpu)) + offset;

	if (offset < 0)

		return false;

		return offset;



	switch (vmcs_field_type(field)) {

	case VMCS_FIELD_TYPE_U16:

		*(u16 *)p = field_value;

		return true;

		return 0;

	case VMCS_FIELD_TYPE_U32:

		*(u32 *)p = field_value;

		return true;

		return 0;

	case VMCS_FIELD_TYPE_U64:

		*(u64 *)p = field_value;

		return true;

		return 0;

	case VMCS_FIELD_TYPE_NATURAL_WIDTH:

		*(natural_width *)p = field_value;

		return true;

		return 0;

	default:

		return false; /* can never happen. */

		WARN_ON(1);

		return -ENOENT;

	}



}
@@ -6576,6 +6581,9 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx) 
		case VMCS_FIELD_TYPE_NATURAL_WIDTH:

			field_value = vmcs_readl(field);

			break;

		default:

			WARN_ON(1);

			continue;

		}

		vmcs12_write_any(&vmx->vcpu, field, field_value);

	}
@@ -6621,6 +6629,9 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx) 
			case VMCS_FIELD_TYPE_NATURAL_WIDTH:

				vmcs_writel(field, (long)field_value);

				break;

			default:

				WARN_ON(1);

				break;

			}

		}

	}
@@ -6659,7 +6670,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) 
	/* Decode instruction info and find the field to read */

	field = kvm_register_readl(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 (vmcs12_read_any(vcpu, field, &field_value) < 0) {

		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);

		skip_emulated_instruction(vcpu);

		return 1;
@@ -6729,7 +6740,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu) 
		return 1;

	}



	if (!vmcs12_write_any(vcpu, field, field_value)) {

	if (vmcs12_write_any(vcpu, field, field_value) < 0) {

		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);

		skip_emulated_instruction(vcpu);

		return 1;