[MODERATED] Re: [PATCH 2/2] Guest L1D flush

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Aug 08, 2018 at 12:15:06PM -0700, speck for Jim Mattson wrote:
> [patch 2/2] kvm: x86: Expose X86_FEATURE_FLUSH_L1D to kvm guests
> 
> If this feature is available on the host, it can be exposed to a kvm
> guest.

Are you sure? I was reading the docs and nothing in it said to do this.

In fact the doc suggests that this should not be done in the first place
and instead the ARCH_CAPABILITIES Bit 3 is to be exposed.

> 
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Ben Serebrin <serebrin@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> ---
>  arch/x86/kvm/cpuid.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 7e042e3d47fd5..2a62270d82b69 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -411,7 +411,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>  	/* cpuid 7.0.edx*/
>  	const u32 kvm_cpuid_7_0_edx_x86_features =
>  		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
> -		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES);
> +		F(SPEC_CTRL_SSBD) | F(FLUSH_L1D) | F(ARCH_CAPABILITIES);
>  
>  	/* all calls to cpuid_count() should be made on the same cpu */
>  	get_cpu();
> -- 
> 2.18.0.597.ga71716f1ad-goog
> 
>