linux-kernel - Re: [PATCH 7/7] x86/kvm: Expose LASS feature to VM guest

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Date:   Tue, 7 Feb 2023 11:21:17 +0800
From:   "Wang, Lei" <lei4.wang@...el.com>
To:     Yian Chen <yian.chen@...el.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ravi Shankar <ravi.v.shankar@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Paul Lai <paul.c.lai@...el.com>
Subject: Re: [PATCH 7/7] x86/kvm: Expose LASS feature to VM guest

Could you also CC the KVM mailing list (kvm@...r.kernel.org) for KVM guys to review?

BR,
Lei

On 1/10/2023 1:52 PM, Yian Chen wrote:
> From: Paul Lai <paul.c.lai@...el.com>
> 
> Expose LASS feature which is defined in the CPUID.7.1.EAX
> bit and enabled via the CR4 bit for VM guest.
> 
> Signed-off-by: Paul Lai <paul.c.lai@...el.com>
> Signed-off-by: Yian Chen <yian.chen@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 3 ++-
>  arch/x86/kvm/cpuid.c            | 2 +-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f35f1ff4427b..bd39f45e9b5a 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -125,7 +125,8 @@
>  			  | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR | X86_CR4_PCIDE \
>  			  | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
>  			  | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
> -			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP))
> +			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP \
> +			  | X86_CR4_LASS))
>  
>  #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
>  
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index b14653b61470..e0f53f85f5ae 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -664,7 +664,7 @@ void kvm_set_cpu_caps(void)
>  
>  	kvm_cpu_cap_mask(CPUID_7_1_EAX,
>  		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) | F(AMX_FP16) |
> -		F(AVX_IFMA)
> +		F(AVX_IFMA) | F(LASS)
>  	);
>  
>  	kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,