Re: [PATCH] KVM: VMX: Add instruction rdtscp support for guest

[Avi Kivity <avi@redhat.com>]

On 12/09/2009 11:11 AM, Sheng Yang wrote:
> Before enabling, execution of "rdtscp" in guest would result in #UD.
>
> Signed-off-by: Sheng Yang<sheng@linux.intel.com>
> ---
>   arch/x86/include/asm/vmx.h |    1 +
>   arch/x86/kvm/vmx.c         |    3 ++-
>   2 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 2b49454..8c39320 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -53,6 +53,7 @@
>    */
>   #define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001
>   #define SECONDARY_EXEC_ENABLE_EPT               0x00000002
> +#define SECONDARY_EXEC_RDTSCP			0x00000008
>   #define SECONDARY_EXEC_ENABLE_VPID              0x00000020
>   #define SECONDARY_EXEC_WBINVD_EXITING		0x00000040
>   #define SECONDARY_EXEC_UNRESTRICTED_GUEST	0x00000080
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9a0a2cf..e1a2ed2 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -1243,7 +1243,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>   			SECONDARY_EXEC_ENABLE_VPID |
>   			SECONDARY_EXEC_ENABLE_EPT |
>   			SECONDARY_EXEC_UNRESTRICTED_GUEST |
> -			SECONDARY_EXEC_PAUSE_LOOP_EXITING;
> +			SECONDARY_EXEC_PAUSE_LOOP_EXITING |
> +			SECONDARY_EXEC_RDTSCP;
>   		if (adjust_vmx_controls(min2, opt2,
>   					MSR_IA32_VMX_PROCBASED_CTLS2,
>   					&_cpu_based_2nd_exec_control)<  0)
>    


Need to save/restore MSR_TSC_AUX (but only if rdtscp in cpuid), support 
MSR_TSC_AUX in get/save, and expose via GET_SUPPORTED_CPUID (only on 
processors which support the feature).

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.