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Date: Tue, 4 Nov 2014 18:33:14 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: tiejun.chen@...el.com
Subject: [PATCH] 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: Tiejun Chen <tiejun.chen@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/kvm/vmx.c | 51 +++++++++++++++++++++++++++++++--------------------
1 file changed, 31 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 12f6f9a8dd8d..0ee148f1687f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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;
--
1.8.3.1
--
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