Re: [Xen-devel] [PATCH v3 1/3] Nested VMX: Check VMX capability before read VMX related MSRs.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.09.13 at 04:52, Yang Zhang <yang.z.zhang@xxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vmx/vmcs.c
> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
> @@ -78,6 +78,7 @@ static DEFINE_PER_CPU(struct list_head, active_vmcs_list);
>  static DEFINE_PER_CPU(bool_t, vmxon);
>  
>  static u32 vmcs_revision_id __read_mostly;
> +u32 vmx_basic_msr_low, vmx_basic_msr_high;

This should be a single 64-bit variable.

> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -31,6 +31,7 @@
>  static DEFINE_PER_CPU(u64 *, vvmcs_buf);
>  
>  static void nvmx_purge_vvmcs(struct vcpu *v);
> +extern u32 vmx_basic_msr_high;

No declarations in source files please; they belong into header files
(which ought to be included by producer and consumer, so that
eventual inconsistencies can be caught by the compiler).

> +    /*
> +     * Those MSRs are available only when bit 55 of
> +     * MSR_IA32_VMX_BASIC is set.
> +     */
> +    switch (msr) {

Coding style.

> +    case MSR_IA32_VMX_TRUE_PINBASED_CTLS:
> +    case MSR_IA32_VMX_TRUE_PROCBASED_CTLS:
> +    case MSR_IA32_VMX_TRUE_EXIT_CTLS:
> +    case MSR_IA32_VMX_TRUE_ENTRY_CTLS:
> +        if ( !(vmx_basic_msr_high & VMX_BASIC_DEFAULT1_ZERO >> 32) )

With the switch to a single 64-bit variable this will get cleaned up
anyway, but for the future: This would need full parenthesization.

Jan


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