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

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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: Tiejun Chen <tiejun.chen@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-11-04 18:31:19 +01:00
parent 34a1cd60d1
commit a2ae9df7c9
1 changed files with 32 additions and 21 deletions
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53
arch/x86/kvm/vmx.c
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@ -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,
unsigned long field, u64 *ret)
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,
unsigned long field, u64 field_value){
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;