Re: [PATCH v2] KVM: nVMX: Advertise IA32_PAT in VM exit control

[Paolo Bonzini <pbonzini@redhat.com>]

----- Original Message -----
> From: "Arthur Chunqi Li" <yzt356@gmail.com>
> To: kvm@vger.kernel.org
> Cc: "jan kiszka" <jan.kiszka@web.de>, gleb@redhat.com, pbonzini@redhat.com, "Arthur Chunqi Li" <yzt356@gmail.com>
> Sent: Monday, August 5, 2013 1:18:13 PM
> Subject: [PATCH v2] KVM: nVMX: Advertise IA32_PAT in VM exit control
> 
> Advertise VM_EXIT_SAVE_IA32_PAT and VM_EXIT_LOAD_IA32_PAT.
> 
> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
> ---
> 
> ChangeLog to v1:
> 	Add host features check. Format is the same as "entry controls".
> 
>  arch/x86/kvm/vmx.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 396572d..fd451c1 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2191,14 +2191,16 @@ static __init void nested_vmx_setup_ctls_msrs(void)
>  	 * If bit 55 of VMX_BASIC is off, bits 0-8 and 10, 11, 13, 14, 16 and
>  	 * 17 must be 1.
>  	 */
> +	rdmsr(MSR_IA32_VMX_EXIT_CTLS,
> +		nested_vmx_exit_ctls_low, nested_vmx_exit_ctls_high);
>  	nested_vmx_exit_ctls_low = VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
> +	nested_vmx_exit_ctls_high &=
> +		VM_EXIT_LOAD_IA32_PAT | VM_EXIT_SAVE_IA32_PAT;
> +	nested_vmx_exit_ctls_high |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
>  	/* Note that guest use of VM_EXIT_ACK_INTR_ON_EXIT is not supported. */
>  #ifdef CONFIG_X86_64
> -	nested_vmx_exit_ctls_high = VM_EXIT_HOST_ADDR_SPACE_SIZE;
> -#else
> -	nested_vmx_exit_ctls_high = 0;
> +	nested_vmx_exit_ctls_high |= VM_EXIT_HOST_ADDR_SPACE_SIZE;

I think you should clear the bit if !X86_64 (and not do anything if
X86_64, the bit should be already set in MSR_IA32_VMX_EXIT_CTLS).

Paolo

>  #endif
> -	nested_vmx_exit_ctls_high |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
>  
>  	/* entry controls */
>  	rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
> --
> 1.7.9.5
> 
>