Re: [PATCH 14/27] nVMX: Implement VMREAD and VMWRITE

[Avi Kivity <avi@redhat.com>]

  On 10/17/2010 12:10 PM, Nadav Har'El wrote:
> Implement the VMREAD and VMWRITE instructions. With these instructions, L1
> can read and write to the VMCS it is holding. The values are read or written
> to the fields of the vmcs_fields structure introduced in the previous patch.
>
>
> +
> +static inline bool 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;
> +
> +	p = ((char *)(get_vmcs12_fields(vcpu))) + offset;
> +
> +	switch (vmcs_field_type(field)) {
> +	case VMCS_FIELD_TYPE_ULONG:
> +		*ret = *((unsigned long *)p);

The cast here should depend on guest mode.  A !is_long_mode() guest 
needs to cast this to u32.

> +		return 1;
> +	case VMCS_FIELD_TYPE_U16:
> +		*ret = (u16) *((unsigned long *)p);
> +		return 1;
> +	case VMCS_FIELD_TYPE_U32:
> +		*ret = (u32) *((unsigned long *)p);
> +		return 1;
> +	case VMCS_FIELD_TYPE_U64:
> +		*ret = *((u64 *)p);

Ditto.

> +		return 1;
> +	default:
> +		return 0; /* can never happen. */
> +	}
> +}
> +
> +
> +static int handle_vmwrite(struct kvm_vcpu *vcpu)
> +{
> +	unsigned long field;
> +	u64 field_value = 0;
> +	gva_t gva;
> +	int field_type;
> +	unsigned long exit_qualification   = vmcs_readl(EXIT_QUALIFICATION);
> +	u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
> +	char *p;
> +	short offset;
> +
> +	if (!nested_vmx_check_permission(vcpu))
> +		return 1;
> +
> +	if (vmx_instruction_info&  (1u<<  10))
> +		field_value = kvm_register_read(vcpu,
> +			(((vmx_instruction_info)>>  3)&  0xf));
> +	else {
> +		if (get_vmx_mem_address(vcpu, exit_qualification,
> +				vmx_instruction_info,&gva))
> +			return 1;
> +		if(kvm_read_guest_virt(gva,&field_value,
> +				(is_long_mode(vcpu) ? 8 : 4), vcpu, NULL)){

Whitespace.

> +			kvm_queue_exception(vcpu, PF_VECTOR);
> +			return 1;
> +		}
> +	}
> +
> +
> +	field = kvm_register_read(vcpu, (((vmx_instruction_info)>>  28)&  0xf));
> +
> +	if (vmcs_field_readonly(field)) {
> +		nested_vmx_failValid(vcpu,
> +			VMXERR_VMWRITE_READ_ONLY_VMCS_COMPONENT);
> +		skip_emulated_instruction(vcpu);
> +		return 1;
> +	}
> +
> +	field_type = vmcs_field_type(field);
> +
> +	offset = vmcs_field_to_offset(field);
> +	if (offset<  0) {
> +		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
> +		skip_emulated_instruction(vcpu);
> +		return 1;
> +	}
> +	p = ((char *) get_vmcs12_fields(vcpu)) + offset;
> +
> +	switch (field_type) {
> +	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:
> +#ifdef CONFIG_X86_64
> +		*(unsigned long *)p = field_value;
> +#else
> +		*(unsigned long *)p = field_value;
> +		*(((unsigned long *)p)+1) = field_value>>  32;

Depend on guest bitness here, not host bitness.  32-bit guests only 
write the first word.

> +#endif
> +		break;
> +	case VMCS_FIELD_TYPE_ULONG:
> +		*(unsigned long *)p = field_value;
> +		break;
> +	default:
> +		nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
> +		skip_emulated_instruction(vcpu);
> +		return 1;
> +	}
> +
> +	nested_vmx_succeed(vcpu);
> +	skip_emulated_instruction(vcpu);
> +	return 1;
> +}
> +

-- 
error compiling committee.c: too many arguments to function