Messages in this thread | | | Subject | Re: [PATCH v3] x86/speculation/l1tf: Add KConfig for setting the L1D cache flush mode | From | Waiman Long <> | Date | Sun, 5 Jul 2020 11:56:56 -0400 |
| |
On 7/5/20 11:23 AM, Mike Rapoport wrote: >> Nothing prevents people from continuing to use the command line >> options if they want, right? This just allows a different default. >> So if a distro is security focused and decided that it wanted a slower >> / more secure default then it could ship that way but individual users >> could still override, right? > Well, nothing prevents you from continuing to use the command line as > well;-) > > I can see why whould you want an ability to select compile time default > for an option, but I'm really not thrilled by the added ifdefery. >
It turns out that CONFIG_KVM_VMENTRY_L1D_FLUSH values match the enum vmx_l1d_flush_state values. So one way to reduce the ifdefery is to do, for example,
+#ifdef CONFIG_KVM_VMENTRY_L1D_FLUSH +#define VMENTER_L1D_FLUSH_DEFAULT CONFIG_KVM_VMENTRY_L1D_FLUSH +#else +#define VMENTER_L1D_FLUSH_DEFAULT VMENTER_L1D_FLUSH_AUTO #endif -enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_DEFAULT;
Of course, we may need to add a comment on enum vmx_l1d_flush_state definition to highlight the dependency of CONFIG_KVM_VMENTRY_L1D_FLUSH on it to avoid future mismatch.
Cheers, Longman
| |