Re: [PATCH v2] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode

[Xiaoyao Li]

On 7/3/2020 5:38 AM, Abhishek Bhardwaj wrote:
> This change adds a new kernel configuration that sets the l1d cache
> flush setting at compile time rather than at run time.
>
> Signed-off-by: Abhishek Bhardwaj <abhishekbh@xxxxxxxxxx>
>
> ---
>
> Changes in v2:
> - Fix typo in the help of the new KConfig.
>
>   arch/x86/kernel/cpu/bugs.c |  8 ++++++++
>   arch/x86/kvm/Kconfig       | 17 +++++++++++++++++
>   2 files changed, 25 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index 0b71970d2d3d2..1dcc875cf5547 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -1406,7 +1406,15 @@ enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
>   #if IS_ENABLED(CONFIG_KVM_INTEL)
>   EXPORT_SYMBOL_GPL(l1tf_mitigation);
>   #endif
> +#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1)
> +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NEVER;
> +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2)
> +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_COND;
> +#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3)
> +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_ALWAYS;
> +#else
>   enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
> +#endif

how about

enum vmx_l1d_flush_state l1tf_vmx_mitigation =
#if (CONFIG_KVM_VMENTRY_L1D_FLUSH == 1)
	VMENTER_L1D_FLUSH_NEVER;
#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 2)
	VMENTER_L1D_FLUSH_COND;
#elif (CONFIG_KVM_VMENTRY_L1D_FLUSH == 3)
	VMENTER_L1D_FLUSH_ALWAYS;
#else
	VMENTER_L1D_FLUSH_AUTO;
#endif