From a2ae9df7c991eca6c1ee6f42dbb18701a64175c3 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 4 Nov 2014 18:31:19 +0100 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 53 ++++++++++++++++++++++++++++------------------ 1 file changed, 32 insertions(+), 21 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 12f6f9a8dd8..d6e3ddace07 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; @@ -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; -- 2.41.0